update to 4.4.2

.travis.yml

@@ -1,7 +1,3 @@
-sudo: false
 language: java
 jdk:
-  - oraclejdk8
+  - openjdk11
-cache:
-  directories:
-    - $HOME/.m2

README.adoc

@@ -17,7 +17,7 @@ original [Google Guice Core Library](https://github.com/google/guice):
 - code is conforming to JRE `compact1` profile 
 - the extra AOP stuff was removed (aopalliance/cglib), no intercepting any more
 - removed all logging, uses of java.util.logger.* stuff and logger default binding
-- removed all java.io.Serializable dependent stuff
+- removed all java.io.Serializable dependent stuff. Note: everything which relies to be serializable was removed.
 - reformatted source by IntelliJ and cleaned up source of @author and @since tags
 - target of compilation is Java 8, no support for Java 6/7
 - introduced Gradle as build system

build.gradle

@@ -1,50 +1,43 @@
-
 plugins {
-    id "org.sonarqube" version "2.2"
+    id "org.sonarqube" version "2.8"
+    id "io.codearte.nexus-staging" version "0.21.1"
 }
 
 apply plugin: 'java'
 apply plugin: 'maven'
-apply plugin: 'signing'
-apply plugin: 'findbugs'
-apply plugin: 'pmd'
-apply plugin: 'checkstyle'
-apply plugin: "jacoco"
 
 repositories {
     mavenCentral()
 }
 
-configurations {
-    wagon
-}
-
 dependencies {
-    compile "javax.inject:javax.inject:1"
+    compile "org.xbib:javax-inject:${project.property('javax-inject.version')}"
-    compile 'org.xbib:jsr-305:1.0.0'
+    compile "org.xbib:guava:${project.property('guava.version')}"
-    compile "com.google.guava:guava:21.0"
+    testCompile "org.junit.jupiter:junit-jupiter-api:${project.property('junit.version')}"
-    testCompile "junit:junit:4.12"
+    testCompile "org.junit.jupiter:junit-jupiter-params:${project.property('junit.version')}"
-    testCompile "org.apache.logging.log4j:log4j-slf4j-impl:2.7"
+    testCompile "org.junit.jupiter:junit-jupiter-engine:${project.property('junit.version')}"
-    testCompile "org.apache.logging.log4j:log4j-core:2.7"
+    testCompile "org.junit.vintage:junit-vintage-engine:${project.property('junit.version')}"
-    testCompile "javax.inject:javax.inject-tck:1"
+    testCompile "junit:junit:${project.property('junit4.version')}"
-    testCompile "com.google.guava:guava-testlib:21.0"
+    // Helper for com.google.common.testing.GcFinalization, com.google.common.testing.EqualsTester
-    wagon 'org.apache.maven.wagon:wagon-ssh-external:2.10'
+    testCompile "com.google.guava:guava-testlib:28.1-jre"
 }
 
-sourceCompatibility = JavaVersion.VERSION_1_8
+compileJava {
-targetCompatibility = JavaVersion.VERSION_1_8
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
+compileTestJava {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
 
-[compileJava, compileTestJava]*.options*.encoding = 'UTF-8'
 tasks.withType(JavaCompile) {
-    options.compilerArgs << "-Xlint:all" << "-profile" << "compact1"
+    options.compilerArgs << "-Xlint:all,-fallthrough"
 }
 
 test {
-    exclude '*$*'
+    useJUnitPlatform()
-    exclude '**/ErrorHandlingTest*'
-    exclude '**/OSGiContainerTest*'
-    exclude '**/ScopesTest*'
-    exclude '**/TypeConversionTest*'
     testLogging {
         showStandardStreams = false
         exceptionFormat = 'full'
@@ -55,18 +48,145 @@ task sourcesJar(type: Jar, dependsOn: classes) {
     classifier 'sources'
     from sourceSets.main.allSource
 }
+
 task javadocJar(type: Jar, dependsOn: javadoc) {
     classifier 'javadoc'
 }
+
 artifacts {
     archives sourcesJar, javadocJar
 }
-if (project.hasProperty('signing.keyId')) {
+
-    signing {
+ext {
-        sign configurations.archives
+    user = 'xbib'
+    projectName = 'guice'
+    projectDescription = 'Guice for Java'
+    scmUrl = 'https://github.com/xbib/guice'
+    scmConnection = 'scm:git:git://github.com/xbib/guice.git'
+    scmDeveloperConnection = 'scm:git:git://github.com/xbib/guice.git'
+}
+
+task sonatypeUpload(type: Upload) {
+    configuration = configurations.archives
+    uploadDescriptor = true
+    repositories {
+        if (project.hasProperty('ossrhUsername')) {
+            mavenDeployer {
+                beforeDeployment { MavenDeployment deployment -> signing.signPom(deployment) }
+                repository(url: uri(ossrhReleaseUrl)) {
+                    authentication(userName: ossrhUsername, password: ossrhPassword)
+                }
+                snapshotRepository(url: uri(ossrhSnapshotUrl)) {
+                    authentication(userName: ossrhUsername, password: ossrhPassword)
+                }
+                pom.project {
+                    groupId project.group
+                    artifactId project.name
+                    version project.version
+                    name project.name
+                    description projectDescription
+                    packaging 'jar'
+                    inceptionYear '2016'
+                    url scmUrl
+                    organization {
+                        name 'xbib'
+                        url 'http://xbib.org'
+                    }
+                    developers {
+                        developer {
+                            id user
+                            name 'Jörg Prante'
+                            email 'joergprante@gmail.com'
+                            url 'https://github.com/jprante'
+                        }
+                    }
+                    scm {
+                        url scmUrl
+                        connection scmConnection
+                        developerConnection scmDeveloperConnection
+                    }
+                    licenses {
+                        license {
+                            name 'The Apache License, Version 2.0'
+                            url 'http://www.apache.org/licenses/LICENSE-2.0.txt'
+                        }
+                    }
+                }
+            }
+        }
     }
 }
 
-apply from: "${rootProject.projectDir}/gradle/ext.gradle"
+
-apply from: "${rootProject.projectDir}/gradle/publish.gradle"
+nexusStaging {
-apply from: "${rootProject.projectDir}/gradle/sonarqube.gradle"
+    packageGroup = "org.xbib"
+}
+
+/*
+spotbugs {
+    effort = "max"
+    reportLevel = "low"
+}
+
+tasks.withType(com.github.spotbugs.SpotBugsTask) {
+    ignoreFailures = true
+    reports {
+        xml.enabled = false
+        html.enabled = true
+    }
+}
+
+tasks.withType(Pmd) {
+    ignoreFailures = true
+    reports {
+        xml.enabled = true
+        html.enabled = true
+    }
+}
+
+tasks.withType(Checkstyle) {
+    ignoreFailures = true
+    reports {
+        xml.enabled = true
+        html.enabled = true
+    }
+}
+
+pmd {
+    toolVersion = '6.11.0'
+    ruleSets = ['category/java/bestpractices.xml']
+}
+
+checkstyle {
+    configFile = rootProject.file('config/checkstyle/checkstyle.xml')
+    ignoreFailures = true
+    showViolations = false
+}
+
+sonarqube {
+    properties {
+        property "sonar.projectName", "${project.group} ${project.name}"
+        property "sonar.sourceEncoding", "UTF-8"
+        property "sonar.tests", "src/test/java"
+        property "sonar.scm.provider", "git"
+    }
+}
+*/
+
+afterEvaluate {
+    compileJava {
+        inputs.property("moduleName", 'org.xbib.guice')
+        doFirst {
+            options.compilerArgs = ['--module-path', classpath.asPath]
+            classpath = files()
+        }
+    }
+    javadoc {
+        inputs.property("moduleName", 'org.xbib.guice')
+        doFirst {
+            options.addStringOption('Xdoclint:none', '-quiet')
+            options.addStringOption('-module-path', classpath.asPath)
+            classpath = files()
+        }
+    }
+}

gradle.properties

@@ -1,3 +1,11 @@
 group = org.xbib
 name = guice
-version = 4.0.4
+version = 4.4.2
+
+javax-inject.version = 1
+guava.version = 28.1
+
+# test
+junit.version = 5.5.2
+junit4.version = 4.12
+log4j.version = 2.12.1

gradle/ext.gradle

@@ -1,8 +0,0 @@
-ext {
-    user = 'xbib'
-    projectName = 'guice'
-    projectDescription = 'Guice for Java'
-    scmUrl = 'https://github.com/xbib/guice'
-    scmConnection = 'scm:git:git://github.com/xbib/guice.git'
-    scmDeveloperConnection = 'scm:git:git://github.com/xbib/guice.git'
-}

gradle/publish.gradle

@@ -1,66 +0,0 @@
-
-task xbibUpload(type: Upload) {
-    configuration = configurations.archives
-    uploadDescriptor = true
-    repositories {
-        if (project.hasProperty('xbibUsername')) {
-            mavenDeployer {
-                configuration = configurations.wagon
-                repository(url: uri('scpexe://xbib.org/repository')) {
-                        authentication(userName: xbibUsername, privateKey: xbibPrivateKey)
-                }
-            }
-        }
-    }
-}
-
-task sonatypeUpload(type: Upload) {
-    configuration = configurations.archives
-    uploadDescriptor = true
-    repositories {
-        if (project.hasProperty('ossrhUsername')) {
-            mavenDeployer {
-                beforeDeployment { MavenDeployment deployment -> signing.signPom(deployment) }
-                repository(url: uri(ossrhReleaseUrl)) {
-                        authentication(userName: ossrhUsername, password: ossrhPassword)
-                }
-                snapshotRepository(url: uri(ossrhSnapshotUrl)) {
-                        authentication(userName: ossrhUsername, password: ossrhPassword)
-                }
-                pom.project {
-                    groupId project.group
-                    artifactId project.name
-                    version project.version
-                    name project.name
-                    description projectDescription
-                    packaging 'jar'
-                    inceptionYear '2016'
-                    url scmUrl
-                    organization {
-                        name 'xbib'
-                        url 'http://xbib.org'
-                    }
-                    developers {
-                        developer {
-                            id user
-                            name 'Jörg Prante'
-                            email 'joergprante@gmail.com'
-                            url 'https://github.com/jprante'
-                        }
-                    }
-                    scm {
-                        url scmUrl
-                        connection scmConnection
-                        developerConnection scmDeveloperConnection
-                    }
-                    licenses {
-                        license {
-                            name 'The Apache License, Version 2.0'
-                            url 'http://www.apache.org/licenses/LICENSE-2.0.txt'
-                        }
-                    }
-                }
-            }
-        }
-    }
-}

gradle/sonarqube.gradle

@@ -1,41 +0,0 @@
-tasks.withType(FindBugs) {
-    ignoreFailures = true
-    reports {
-        xml.enabled = true
-        html.enabled = false
-    }
-}
-tasks.withType(Pmd) {
-    ignoreFailures = true
-    reports {
-        xml.enabled = true
-        html.enabled = true
-    }
-}
-tasks.withType(Checkstyle) {
-    ignoreFailures = true
-    reports {
-        xml.enabled = true
-        html.enabled = true
-    }
-}
-
-jacocoTestReport {
-    reports {
-        xml.enabled true
-        csv.enabled false
-        xml.destination "${buildDir}/reports/jacoco-xml"
-        html.destination "${buildDir}/reports/jacoco-html"
-    }
-}
-
-sonarqube {
-    properties {
-        property "sonar.projectName", "${project.group} ${project.name}"
-        property "sonar.sourceEncoding", "UTF-8"
-        property "sonar.tests", "src/test/java"
-        property "sonar.scm.provider", "git"
-        property "sonar.java.coveragePlugin", "jacoco"
-        property "sonar.junit.reportsPath", "build/test-results/test/"
-    }
-}

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Fri Feb 03 12:38:43 CET 2017
+#Wed Nov 20 21:27:17 CET 2019
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.2-all.zip
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-3.3-bin.zip
+zipStoreBase=GRADLE_USER_HOME

gradlew

@@ -1,5 +1,21 @@
 #!/usr/bin/env sh
 
+#
+# Copyright 2015 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
 ##############################################################################
 ##
 ##  Gradle start up script for UN*X
@@ -28,7 +44,7 @@ APP_NAME="Gradle"
 APP_BASE_NAME=`basename "$0"`
 
 # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS=""
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"
@@ -109,8 +125,8 @@ if $darwin; then
     GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
 fi
 
-# For Cygwin, switch paths to Windows format before running java
+# For Cygwin or MSYS, switch paths to Windows format before running java
-if $cygwin ; then
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
     APP_HOME=`cygpath --path --mixed "$APP_HOME"`
     CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
     JAVACMD=`cygpath --unix "$JAVACMD"`

gradlew.bat

@@ -1,3 +1,19 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
 @if "%DEBUG%" == "" @echo off
 @rem ##########################################################################
 @rem
@@ -14,7 +30,7 @@ set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
 @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-set DEFAULT_JVM_OPTS=
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
 
 @rem Find java.exe
 if defined JAVA_HOME goto findJavaFromJavaHome

src/main/java/com/google/inject/AbstractModule.java

@@ -36,6 +36,7 @@ public abstract class AbstractModule implements Module {
 
     Binder binder;
 
+    @Override
     public final synchronized void configure(Binder builder) {
         checkState(this.binder == null, "Re-entry is not allowed.");
 
@@ -63,8 +64,7 @@ public abstract class AbstractModule implements Module {
     /**
      * @see Binder#bindScope(Class, Scope)
      */
-    protected void bindScope(Class<? extends Annotation> scopeAnnotation,
+    protected void bindScope(Class<? extends Annotation> scopeAnnotation, Scope scope) {
-                             Scope scope) {
         binder().bindScope(scopeAnnotation, scope);
     }
 

src/main/java/com/google/inject/Binder.java

@@ -367,7 +367,7 @@ public interface Binder {
      *                      their clients.
      * @return a binder that shares its configuration with this binder.
      */
-    Binder skipSources(Class... classesToSkip);
+    Binder skipSources(Class<?>... classesToSkip);
 
     /**
      * Creates a new private child environment for bindings and other configuration. The returned

src/main/java/com/google/inject/ConfigurationException.java

@@ -1,7 +1,7 @@
 package com.google.inject;
 
 import com.google.common.collect.ImmutableSet;
-import com.google.inject.internal.Errors;
+import com.google.inject.internal.Messages;
 import com.google.inject.spi.Message;
 
 import java.util.Collection;
@@ -24,7 +24,7 @@ public final class ConfigurationException extends RuntimeException {
      */
     public ConfigurationException(Iterable<Message> messages) {
         this.messages = ImmutableSet.copyOf(messages);
-        initCause(Errors.getOnlyCause(this.messages));
+        initCause(Messages.getOnlyCause(this.messages));
     }
 
     /**
@@ -59,6 +59,6 @@ public final class ConfigurationException extends RuntimeException {
 
     @Override
     public String getMessage() {
-        return Errors.format("Guice configuration errors", messages);
+        return Messages.formatMessages("Guice configuration errors", messages);
     }
 }

src/main/java/com/google/inject/CreationException.java

@@ -1,7 +1,7 @@
 package com.google.inject;
 
 import com.google.common.collect.ImmutableSet;
-import com.google.inject.internal.Errors;
+import com.google.inject.internal.Messages;
 import com.google.inject.spi.Message;
 
 import java.util.Collection;
@@ -12,9 +12,9 @@ import static com.google.common.base.Preconditions.checkArgument;
  * Thrown when errors occur while creating a {@link Injector}. Includes a list of encountered
  * errors. Clients should catch this exception, log it, and stop execution.
  */
+@SuppressWarnings("serial")
 public class CreationException extends RuntimeException {
 
-    private static final long serialVersionUID = 0;
     private final ImmutableSet<Message> messages;
 
     /**
@@ -23,7 +23,7 @@ public class CreationException extends RuntimeException {
     public CreationException(Collection<Message> messages) {
         this.messages = ImmutableSet.copyOf(messages);
         checkArgument(!this.messages.isEmpty());
-        initCause(Errors.getOnlyCause(this.messages));
+        initCause(Messages.getOnlyCause(this.messages));
     }
 
     /**
@@ -35,6 +35,6 @@ public class CreationException extends RuntimeException {
 
     @Override
     public String getMessage() {
-        return Errors.format("Unable to create injector, see the following errors", messages);
+        return Messages.formatMessages("Unable to create injector, see the following errors", messages);
     }
 }

src/main/java/com/google/inject/Guice.java

@@ -76,11 +76,7 @@ public final class Guice {
      * @throws CreationException if one or more errors occur during injector
      *                           construction
      */
-    public static Injector createInjector(Stage stage,
+    public static Injector createInjector(Stage stage, Iterable<? extends Module> modules) {
-                                          Iterable<? extends Module> modules) {
+        return new InternalInjectorCreator().stage(stage).addModules(modules).build();
-        return new InternalInjectorCreator()
-                .stage(stage)
-                .addModules(modules)
-                .build();
     }
 }

src/main/java/com/google/inject/Injector.java

@@ -1,5 +1,7 @@
 package com.google.inject;
 
+import com.google.inject.spi.Element;
+import com.google.inject.spi.InjectionPoint;
 import com.google.inject.spi.TypeConverterBinding;
 
 import java.lang.annotation.Annotation;
@@ -225,4 +227,37 @@ public interface Injector {
      * <p>This method is part of the Guice SPI and is intended for use by tools and extensions.
      */
     Set<TypeConverterBinding> getTypeConverterBindings();
+
+
+    /**
+     * Returns the elements that make up this injector. Note that not all kinds of elements are
+     * returned.
+     *
+     * <p>The returned list does not include elements inherited from a {@link #getParent() parent
+     * injector}, should one exist.
+     *
+     * <p>The returned list is immutable; it contains only the elements that were present when {@link
+     * #getElements} was invoked. Subsequent calls may return a list with additional elements.
+     *
+     * <p>The returned list does not include data inherited from a {@link #getParent() parent
+     * injector}, should one exist.
+     *
+     * <p>This method is part of the Guice SPI and is intended for use by tools and extensions.
+     */
+    List<Element> getElements();
+
+    /**
+     * Returns the injection points created for calls to {@link #getMembersInjector} (either directly
+     * or indirectly, e.g. through {@link #injectMembers}.
+     *
+     * <p>This excludes any injection points from elements (which are accessible from each element via
+     * the SPI), unless {@link #getMembersInjector} or {@link #injectMembers} were also called for the
+     * same key.
+     *
+     * <p>The returned multimap does not include data inherited from a {@link #getParent() parent
+     * injector}, should one exist.
+     *
+     * <p>This method is part of the Guice SPI and is intended for use by tools and extensions.
+     */
+    Map<TypeLiteral<?>, List<InjectionPoint>> getAllMembersInjectorInjectionPoints();
 }

src/main/java/com/google/inject/Key.java

@@ -39,8 +39,13 @@ public class Key<T> {
     private final AnnotationStrategy annotationStrategy;
 
     private final TypeLiteral<T> typeLiteral;
+
     private final int hashCode;
-    private final Supplier<String> toStringSupplier;
+
+    // This field is updated using the 'Data-Race-Ful' lazy intialization pattern
+    // See http://jeremymanson.blogspot.com/2008/12/benign-data-races-in-java.html for a detailed
+    // explanation.
+    private String toString;
 
     /**
      * Constructs a new key. Derives the type from this class's type parameter.
@@ -60,7 +65,6 @@ public class Key<T> {
         this.typeLiteral = MoreTypes.canonicalizeForKey(
                 (TypeLiteral<T>) TypeLiteral.fromSuperclassTypeParameter(getClass()));
         this.hashCode = computeHashCode();
-        this.toStringSupplier = createToStringSupplier();
     }
 
     /**
@@ -82,7 +86,6 @@ public class Key<T> {
         this.typeLiteral = MoreTypes.canonicalizeForKey(
                 (TypeLiteral<T>) TypeLiteral.fromSuperclassTypeParameter(getClass()));
         this.hashCode = computeHashCode();
-        this.toStringSupplier = createToStringSupplier();
     }
 
     /**
@@ -102,7 +105,6 @@ public class Key<T> {
         this.typeLiteral = MoreTypes.canonicalizeForKey(
                 (TypeLiteral<T>) TypeLiteral.fromSuperclassTypeParameter(getClass()));
         this.hashCode = computeHashCode();
-        this.toStringSupplier = createToStringSupplier();
     }
 
     /**
@@ -113,7 +115,6 @@ public class Key<T> {
         this.annotationStrategy = annotationStrategy;
         this.typeLiteral = MoreTypes.canonicalizeForKey((TypeLiteral<T>) TypeLiteral.get(type));
         this.hashCode = computeHashCode();
-        this.toStringSupplier = createToStringSupplier();
     }
 
     /**
@@ -123,14 +124,12 @@ public class Key<T> {
         this.annotationStrategy = annotationStrategy;
         this.typeLiteral = MoreTypes.canonicalizeForKey(typeLiteral);
         this.hashCode = computeHashCode();
-        this.toStringSupplier = createToStringSupplier();
     }
 
     /**
      * Gets a key for an injection type and an annotation strategy.
      */
-    static <T> Key<T> get(Class<T> type,
+    static <T> Key<T> get(Class<T> type, AnnotationStrategy annotationStrategy) {
-                          AnnotationStrategy annotationStrategy) {
         return new Key<T>(type, annotationStrategy);
     }
 
@@ -144,8 +143,7 @@ public class Key<T> {
     /**
      * Gets a key for an injection type and an annotation type.
      */
-    public static <T> Key<T> get(Class<T> type,
+    public static <T> Key<T> get(Class<T> type, Class<? extends Annotation> annotationType) {
-                                 Class<? extends Annotation> annotationType) {
         return new Key<T>(type, strategyFor(annotationType));
     }
 
@@ -166,8 +164,7 @@ public class Key<T> {
     /**
      * Gets a key for an injection type and an annotation type.
      */
-    public static Key<?> get(Type type,
+    public static Key<?> get(Type type, Class<? extends Annotation> annotationType) {
-                             Class<? extends Annotation> annotationType) {
         return new Key<Object>(type, strategyFor(annotationType));
     }
 
@@ -188,16 +185,14 @@ public class Key<T> {
     /**
      * Gets a key for an injection type and an annotation type.
      */
-    public static <T> Key<T> get(TypeLiteral<T> typeLiteral,
+    public static <T> Key<T> get(TypeLiteral<T> typeLiteral, Class<? extends Annotation> annotationType) {
-                                 Class<? extends Annotation> annotationType) {
         return new Key<T>(typeLiteral, strategyFor(annotationType));
     }
 
     /**
      * Gets a key for an injection type and an annotation.
      */
-    public static <T> Key<T> get(TypeLiteral<T> typeLiteral,
+    public static <T> Key<T> get(TypeLiteral<T> typeLiteral, Annotation annotation) {
-                                 Annotation annotation) {
         return new Key<T>(typeLiteral, strategyFor(annotation));
     }
 
@@ -253,20 +248,6 @@ public class Key<T> {
         return typeLiteral.hashCode() * 31 + annotationStrategy.hashCode();
     }
 
-    /**
-     * @return a {@link Supplier} which memoizes the value for lazy initialization.
-     */
-    private Supplier<String> createToStringSupplier() {
-        // The performance hit on access is acceptable since the intended use is for non-performance-
-        // critical applications.
-        return Suppliers.memoize(new Supplier<String>() {
-            @Override
-            public String get() {
-                return "Key[type=" + typeLiteral + ", annotation=" + annotationStrategy + "]";
-            }
-        });
-    }
-
     /**
      * Gets the key type.
      */
@@ -333,7 +314,14 @@ public class Key<T> {
 
     @Override
     public final String toString() {
-        return toStringSupplier.get();
+        // Note: to not introduce dangerous data races the field should only be read once in this
+        // method.
+        String local = toString;
+        if (local == null) {
+            local = "Key[type=" + typeLiteral + ", annotation=" + annotationStrategy + "]";
+            toString = local;
+        }
+        return local;
     }
 
     /**
@@ -375,21 +363,25 @@ public class Key<T> {
         return new Key<T>(typeLiteral, annotationStrategy.withoutAttributes());
     }
 
-    static enum NullAnnotationStrategy implements AnnotationStrategy {
+    enum NullAnnotationStrategy implements AnnotationStrategy {
         INSTANCE;
 
+        @Override
         public boolean hasAttributes() {
             return false;
         }
 
+        @Override
         public AnnotationStrategy withoutAttributes() {
             throw new UnsupportedOperationException("Key already has no attributes.");
         }
 
+        @Override
         public Annotation getAnnotation() {
             return null;
         }
 
+        @Override
         public Class<? extends Annotation> getAnnotationType() {
             return null;
         }
@@ -401,6 +393,7 @@ public class Key<T> {
     }
 
     interface AnnotationStrategy {
+
         Annotation getAnnotation();
 
         Class<? extends Annotation> getAnnotationType();
@@ -419,18 +412,22 @@ public class Key<T> {
             this.annotation = checkNotNull(annotation, "annotation");
         }
 
+        @Override
         public boolean hasAttributes() {
             return true;
         }
 
+        @Override
         public AnnotationStrategy withoutAttributes() {
             return new AnnotationTypeStrategy(getAnnotationType(), annotation);
         }
 
+        @Override
         public Annotation getAnnotation() {
             return annotation;
         }
 
+        @Override
         public Class<? extends Annotation> getAnnotationType() {
             return annotation.annotationType();
         }
@@ -469,18 +466,22 @@ public class Key<T> {
             this.annotation = annotation;
         }
 
+        @Override
         public boolean hasAttributes() {
             return false;
         }
 
+        @Override
         public AnnotationStrategy withoutAttributes() {
             throw new UnsupportedOperationException("Key already has no attributes.");
         }
 
+        @Override
         public Annotation getAnnotation() {
             return annotation;
         }
 
+        @Override
         public Class<? extends Annotation> getAnnotationType() {
             return annotationType;
         }

src/main/java/com/google/inject/OutOfScopeException.java

@@ -0,0 +1,22 @@
+package com.google.inject;
+
+/**
+ * Thrown from {@link Provider#get} when an attempt is made to access a scoped object while the
+ * scope in question is not currently active.
+ *
+ */
+@SuppressWarnings("serial")
+public final class OutOfScopeException extends RuntimeException {
+
+    public OutOfScopeException(String message) {
+        super(message);
+    }
+
+    public OutOfScopeException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public OutOfScopeException(Throwable cause) {
+        super(cause);
+    }
+}

src/main/java/com/google/inject/PrivateBinder.java

@@ -31,5 +31,5 @@ public interface PrivateBinder extends Binder {
 
     PrivateBinder withSource(Object source);
 
-    PrivateBinder skipSources(Class... classesToSkip);
+    PrivateBinder skipSources(Class<?>... classesToSkip);
 }

src/main/java/com/google/inject/ProvidedBy.java

@@ -2,6 +2,7 @@ package com.google.inject;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.Target;
+import javax.inject.Provider;
 
 import static java.lang.annotation.ElementType.TYPE;
 import static java.lang.annotation.RetentionPolicy.RUNTIME;

src/main/java/com/google/inject/Provider.java

@@ -32,5 +32,6 @@ public interface Provider<T> extends javax.inject.Provider<T> {
      * @throws ProvisionException  if an instance cannot be provided. Such exceptions include messages
      *                             and throwables to describe why provision failed.
      */
+    @Override
     T get();
 }

src/main/java/com/google/inject/ProvisionException.java

@@ -1,7 +1,7 @@
 package com.google.inject;
 
 import com.google.common.collect.ImmutableSet;
-import com.google.inject.internal.Errors;
+import com.google.inject.internal.Messages;
 import com.google.inject.spi.Message;
 
 import java.util.Collection;
@@ -23,7 +23,7 @@ public final class ProvisionException extends RuntimeException {
     public ProvisionException(Iterable<Message> messages) {
         this.messages = ImmutableSet.copyOf(messages);
         checkArgument(!this.messages.isEmpty());
-        initCause(Errors.getOnlyCause(this.messages));
+        initCause(Messages.getOnlyCause(this.messages));
     }
 
     public ProvisionException(String message, Throwable cause) {
@@ -44,6 +44,6 @@ public final class ProvisionException extends RuntimeException {
 
     @Override
     public String getMessage() {
-        return Errors.format("Unable to provision, see the following errors", messages);
+        return Messages.formatMessages("Unable to provision, see the following errors", messages);
     }
 }

src/main/java/com/google/inject/Scopes.java

@@ -28,6 +28,7 @@ public class Scopes {
      * this to "no scope" in your binding.
      */
     public static final Scope NO_SCOPE = new Scope() {
+        @Override
         public <T> Provider<T> scope(Key<T> key, Provider<T> unscoped) {
             return unscoped;
         }
@@ -37,21 +38,26 @@ public class Scopes {
             return "Scopes.NO_SCOPE";
         }
     };
+
     private static final BindingScopingVisitor<Boolean> IS_SINGLETON_VISITOR
-            = new BindingScopingVisitor<Boolean>() {
+            = new BindingScopingVisitor<>() {
+        @Override
         public Boolean visitNoScoping() {
             return false;
         }
 
+        @Override
         public Boolean visitScopeAnnotation(Class<? extends Annotation> scopeAnnotation) {
             return scopeAnnotation == Singleton.class
                     || scopeAnnotation == javax.inject.Singleton.class;
         }
 
+        @Override
         public Boolean visitScope(Scope scope) {
             return scope == Scopes.SINGLETON;
         }
 
+        @Override
         public Boolean visitEagerSingleton() {
             return true;
         }
@@ -107,18 +113,22 @@ public class Scopes {
                                    final Class<? extends Annotation> scopeAnnotation) {
         do {
             boolean matches = binding.acceptScopingVisitor(new BindingScopingVisitor<Boolean>() {
+                @Override
                 public Boolean visitNoScoping() {
                     return false;
                 }
 
+                @Override
                 public Boolean visitScopeAnnotation(Class<? extends Annotation> visitedAnnotation) {
                     return visitedAnnotation == scopeAnnotation;
                 }
 
+                @Override
                 public Boolean visitScope(Scope visitedScope) {
                     return visitedScope == scope;
                 }
 
+                @Override
                 public Boolean visitEagerSingleton() {
                     return false;
                 }

src/main/java/com/google/inject/TypeLiteral.java

@@ -170,7 +170,7 @@ public class TypeLiteral<T> {
         // this implementation is made a little more complicated in an attempt to avoid object-creation
         while (true) {
             if (toResolve instanceof TypeVariable) {
-                TypeVariable original = (TypeVariable) toResolve;
+                TypeVariable<?> original = (TypeVariable) toResolve;
                 toResolve = MoreTypes.resolveTypeVariable(type, rawType, original);
                 if (toResolve == original) {
                     return toResolve;

src/main/java/com/google/inject/assistedinject/FactoryProvider.java

@@ -13,6 +13,7 @@ import com.google.inject.Provider;
 import com.google.inject.TypeLiteral;
 import com.google.inject.internal.Errors;
 import com.google.inject.internal.ErrorsException;
+import com.google.inject.internal.Messages;
 import com.google.inject.spi.Dependency;
 import com.google.inject.spi.HasDependencies;
 import com.google.inject.spi.Message;
@@ -256,7 +257,7 @@ public class FactoryProvider<F> implements Provider<F>, HasDependencies {
     }
 
     private static ConfigurationException newConfigurationException(String format, Object... args) {
-        return new ConfigurationException(ImmutableSet.of(new Message(Errors.format(format, args))));
+        return new ConfigurationException(ImmutableSet.of(new Message(Messages.format(format, args))));
     }
 
     @Inject
@@ -355,9 +356,9 @@ public class FactoryProvider<F> implements Provider<F>, HasDependencies {
         };
 
         @SuppressWarnings("unchecked") // we imprecisely treat the class literal of T as a Class<T>
-                Class<F> factoryRawType = (Class<F>) (Class<?>) factoryType.getRawType();
+        Class<F> factoryRawType = (Class<F>) factoryType.getRawType();
         return factoryRawType.cast(Proxy.newProxyInstance(factoryRawType.getClassLoader(),
-                new Class[]{factoryRawType}, invocationHandler));
+                new Class<?>[]{factoryRawType}, invocationHandler));
     }
 
     @Override

src/main/java/com/google/inject/assistedinject/FactoryProvider2.java

@@ -96,7 +96,7 @@ final class FactoryProvider2<F> implements InvocationHandler,
 
         @Override
         public String toString() {
-            return "@" + Assisted.class.getName() + "(value=)";
+            return "@" + Assisted.class.getName() + "(value=\"\")";
         }
     };
     /**

src/main/java/com/google/inject/binder/LinkedBindingBuilder.java

@@ -51,20 +51,17 @@ public interface LinkedBindingBuilder<T> extends ScopedBindingBuilder {
     /**
      * See the EDSL examples at {@link com.google.inject.Binder}.
      */
-    ScopedBindingBuilder toProvider(
+    ScopedBindingBuilder toProvider(Class<? extends javax.inject.Provider<? extends T>> providerType);
-            Class<? extends javax.inject.Provider<? extends T>> providerType);
 
     /**
      * See the EDSL examples at {@link com.google.inject.Binder}.
      */
-    ScopedBindingBuilder toProvider(
+    ScopedBindingBuilder toProvider(TypeLiteral<? extends javax.inject.Provider<? extends T>> providerType);
-            TypeLiteral<? extends javax.inject.Provider<? extends T>> providerType);
 
     /**
      * See the EDSL examples at {@link com.google.inject.Binder}.
      */
-    ScopedBindingBuilder toProvider(
+    ScopedBindingBuilder toProvider(Key<? extends javax.inject.Provider<? extends T>> providerKey);
-            Key<? extends javax.inject.Provider<? extends T>> providerKey);
 
     /**
      * See the EDSL examples at {@link com.google.inject.Binder}.
@@ -74,6 +71,5 @@ public interface LinkedBindingBuilder<T> extends ScopedBindingBuilder {
     /**
      * See the EDSL examples at {@link com.google.inject.Binder}.
      */
-    <S extends T> ScopedBindingBuilder toConstructor(
+    <S extends T> ScopedBindingBuilder toConstructor(Constructor<S> constructor, TypeLiteral<? extends S> type);
-            Constructor<S> constructor, TypeLiteral<? extends S> type);
 }

src/main/java/com/google/inject/internal/AbstractBindingBuilder.java

@@ -18,14 +18,14 @@ import static com.google.common.base.Preconditions.checkNotNull;
 public abstract class AbstractBindingBuilder<T> {
 
     public static final String IMPLEMENTATION_ALREADY_SET = "Implementation is set more than once.";
-    public static final String SINGLE_INSTANCE_AND_SCOPE
+    public static final String SINGLE_INSTANCE_AND_SCOPE =
-            = "Setting the scope is not permitted when binding to a single instance.";
+            "Setting the scope is not permitted when binding to a single instance.";
     public static final String SCOPE_ALREADY_SET = "Scope is set more than once.";
-    public static final String BINDING_TO_NULL = "Binding to null instances is not allowed. "
+    public static final String BINDING_TO_NULL = "Binding to null instances is not allowed. " +
-            + "Use toProvider(Providers.of(null)) if this is your intended behaviour.";
+            "Use toProvider(Providers.of(null)) if this is your intended behaviour.";
     public static final String CONSTANT_VALUE_ALREADY_SET = "Constant value is set more than once.";
-    public static final String ANNOTATION_ALREADY_SPECIFIED
+    public static final String ANNOTATION_ALREADY_SPECIFIED =
-            = "More than one annotation is specified for this binding.";
+            "More than one annotation is specified for this binding.";
 
     protected static final Key<?> NULL_KEY = Key.get(Void.class);
     protected final Binder binder;
@@ -37,7 +37,7 @@ public abstract class AbstractBindingBuilder<T> {
         this.binder = binder;
         this.elements = elements;
         this.position = elements.size();
-        this.binding = new UntargettedBindingImpl<T>(source, key, Scoping.UNSCOPED);
+        this.binding = new UntargettedBindingImpl<>(source, key, Scoping.UNSCOPED);
         elements.add(position, this.binding);
     }
 
@@ -57,8 +57,7 @@ public abstract class AbstractBindingBuilder<T> {
     protected BindingImpl<T> annotatedWithInternal(Class<? extends Annotation> annotationType) {
         checkNotNull(annotationType, "annotationType");
         checkNotAnnotated();
-        return setBinding(binding.withKey(
+        return setBinding(binding.withKey(Key.get(this.binding.getKey().getTypeLiteral(), annotationType)));
-                Key.get(this.binding.getKey().getTypeLiteral(), annotationType)));
     }
 
     /**
@@ -67,8 +66,7 @@ public abstract class AbstractBindingBuilder<T> {
     protected BindingImpl<T> annotatedWithInternal(Annotation annotation) {
         checkNotNull(annotation, "annotation");
         checkNotAnnotated();
-        return setBinding(binding.withKey(
+        return setBinding(binding.withKey(Key.get(this.binding.getKey().getTypeLiteral(), annotation)));
-                Key.get(this.binding.getKey().getTypeLiteral(), annotation)));
     }
 
     public void in(final Class<? extends Annotation> scopeAnnotation) {

src/main/java/com/google/inject/internal/AbstractBindingProcessor.java

@@ -24,7 +24,7 @@ abstract class AbstractBindingProcessor extends AbstractProcessor {
     // It's unfortunate that we have to maintain a blacklist of specific
     // classes, but we can't easily block the whole package because of
     // all our unit tests.
-    private static final Set<Class<?>> FORBIDDEN_TYPES = ImmutableSet.<Class<?>>of(
+    private static final Set<Class<?>> FORBIDDEN_TYPES = ImmutableSet.of(
             AbstractModule.class,
             Binder.class,
             Binding.class,
@@ -93,7 +93,7 @@ abstract class AbstractBindingProcessor extends AbstractProcessor {
      */
     private boolean isOkayDuplicate(BindingImpl<?> original, BindingImpl<?> binding, State state) {
         if (original instanceof ExposedBindingImpl) {
-            ExposedBindingImpl exposed = (ExposedBindingImpl) original;
+            ExposedBindingImpl<?> exposed = (ExposedBindingImpl) original;
             InjectorImpl exposedFrom = (InjectorImpl) exposed.getPrivateElements().getInjector();
             return (exposedFrom == binding.getInjector());
         } else {
@@ -131,16 +131,28 @@ abstract class AbstractBindingProcessor extends AbstractProcessor {
             scoping = Scoping.makeInjectable(scoping, injector, errors);
         }
 
-        protected void scheduleInitialization(final BindingImpl<?> binding) {
+        /**
-            bindingData.addUninitializedBinding(new Runnable() {
+         * Schedule initialization of this binding to occur immediately after all bindings have been
-                public void run() {
+         * initialially processed.
+         */
+        protected void scheduleInitialization(BindingImpl<?> binding) {
+            bindingData.addUninitializedBinding(() -> initializeBinding(binding));
+        }
+
+        /**
+         * Schedule initialization for this binding to occur after all other static initialization of
+         * bindings.
+         */
+        protected void scheduleDelayedInitialization(BindingImpl<?> binding) {
+            bindingData.addDelayedUninitializedBinding(() -> initializeBinding(binding));
+        }
+
+        private void initializeBinding(BindingImpl<?> binding) {
             try {
                 binding.getInjector().initializeBinding(binding, errors.withSource(source));
             } catch (ErrorsException e) {
                 errors.merge(e.getErrors());
             }
         }
-            });
-        }
     }
 }

src/main/java/com/google/inject/internal/Annotations.java

@@ -1,5 +1,7 @@
 package com.google.inject.internal;
 
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
 import com.google.common.base.Function;
 import com.google.common.base.Joiner;
 import com.google.common.base.Joiner.MapJoiner;
@@ -43,14 +45,17 @@ public class Annotations {
             return s.substring(1, s.length() - 1); // cut off brackets
         }
     };
+
     private static final LoadingCache<Class<? extends Annotation>, Annotation> cache =
-            CacheBuilder.newBuilder().weakKeys().build(
+            CacheBuilder.newBuilder()
-                    new CacheLoader<Class<? extends Annotation>, Annotation>() {
+                    .weakKeys()
+                    .build(new CacheLoader<>() {
                         @Override
                         public Annotation load(Class<? extends Annotation> input) {
                             return generateAnnotationImpl(input);
                         }
                     });
+
     private static final AnnotationChecker scopeChecker = new AnnotationChecker(
             Arrays.asList(ScopeAnnotation.class, javax.inject.Scope.class));
     private static final AnnotationChecker bindingAnnotationChecker = new AnnotationChecker(
@@ -90,22 +95,20 @@ public class Annotations {
         return annotationType.cast(Proxy.newProxyInstance(
                 annotationType.getClassLoader(),
                 new Class<?>[]{annotationType},
-                new InvocationHandler() {
+                (proxy, method, args) -> {
-                    @Override
-                    public Object invoke(Object proxy, Method method, Object[] args) throws Exception {
                     String name = method.getName();
-                        if (name.equals("annotationType")) {
+                    switch (name) {
+                        case "annotationType":
                             return annotationType;
-                        } else if (name.equals("toString")) {
+                        case "toString":
                             return annotationToString(annotationType, members);
-                        } else if (name.equals("hashCode")) {
+                        case "hashCode":
                             return annotationHashCode(annotationType, members);
-                        } else if (name.equals("equals")) {
+                        case "equals":
                             return annotationEquals(annotationType, members, args[0]);
-                        } else {
+                        default:
                             return members.get(name);
                     }
-                    }
                 }));
     }
 
@@ -207,6 +210,30 @@ public class Annotations {
         return false;
     }
 
+    private static final boolean QUOTE_MEMBER_VALUES = determineWhetherToQuote();
+
+    public static String memberValueString(String value) {
+        return QUOTE_MEMBER_VALUES ? "\"" + value + "\"" : value;
+    }
+
+    @Retention(RUNTIME)
+    private @interface TestAnnotation {
+        String value();
+    }
+
+    @TestAnnotation("determineWhetherToQuote")
+    private static boolean determineWhetherToQuote() {
+        try {
+            String annotation = Annotations.class
+                            .getDeclaredMethod("determineWhetherToQuote")
+                            .getAnnotation(TestAnnotation.class)
+                            .toString();
+            return annotation.contains("\"determineWhetherToQuote\"");
+        } catch (NoSuchMethodException e) {
+            throw new AssertionError(e);
+        }
+    }
+
     public static boolean isScopeAnnotation(Class<? extends Annotation> annotationType) {
         return scopeChecker.hasAnnotations(annotationType);
     }
@@ -243,8 +270,7 @@ public class Annotations {
     /**
      * Returns the binding annotation on {@code member}, or null if there isn't one.
      */
-    public static Annotation findBindingAnnotation(
+    public static Annotation findBindingAnnotation(Errors errors, Member member, Annotation[] annotations) {
-            Errors errors, Member member, Annotation[] annotations) {
         Annotation found = null;
 
         for (Annotation annotation : annotations) {
@@ -293,6 +319,24 @@ public class Annotations {
         }
     }
 
+    /**
+     * Returns the name the binding should use. This is based on the annotation. If the annotation has
+     * an instance and is not a marker annotation, we ask the annotation for its toString. If it was a
+     * marker annotation or just an annotation type, we use the annotation's name. Otherwise, the name
+     * is the empty string.
+     */
+    public static String nameOf(Key<?> key) {
+        Annotation annotation = key.getAnnotation();
+        Class<? extends Annotation> annotationType = key.getAnnotationType();
+        if (annotation != null && !isMarker(annotationType)) {
+            return key.getAnnotation().toString();
+        } else if (key.getAnnotationType() != null) {
+            return "@" + key.getAnnotationType().getName();
+        } else {
+            return "";
+        }
+    }
+
     /**
      * Checks for the presence of annotations. Caches results because Android doesn't.
      */
@@ -303,7 +347,8 @@ public class Annotations {
          * Returns true if the given class has one of the desired annotations.
          */
         private CacheLoader<Class<? extends Annotation>, Boolean> hasAnnotations =
-                new CacheLoader<Class<? extends Annotation>, Boolean>() {
+                new CacheLoader<>() {
+                    @Override
                     public Boolean load(Class<? extends Annotation> annotationType) {
                         for (Annotation annotation : annotationType.getAnnotations()) {
                             if (annotationTypes.contains(annotation.annotationType())) {
@@ -314,8 +359,8 @@ public class Annotations {
                     }
                 };
 
-        final LoadingCache<Class<? extends Annotation>, Boolean> cache = CacheBuilder.newBuilder().weakKeys()
+        final LoadingCache<Class<? extends Annotation>, Boolean> cache =
-                .build(hasAnnotations);
+                CacheBuilder.newBuilder().weakKeys().build(hasAnnotations);
 
         /**
          * Constructs a new checker that looks for annotations of the given types.

src/main/java/com/google/inject/internal/BindingBuilder.java

@@ -29,24 +29,29 @@ public class BindingBuilder<T> extends AbstractBindingBuilder<T>
         super(binder, elements, source, key);
     }
 
+    @Override
     public BindingBuilder<T> annotatedWith(Class<? extends Annotation> annotationType) {
         annotatedWithInternal(annotationType);
         return this;
     }
 
+    @Override
     public BindingBuilder<T> annotatedWith(Annotation annotation) {
         annotatedWithInternal(annotation);
         return this;
     }
 
+    @Override
     public BindingBuilder<T> to(Class<? extends T> implementation) {
         return to(Key.get(implementation));
     }
 
+    @Override
     public BindingBuilder<T> to(TypeLiteral<? extends T> implementation) {
         return to(Key.get(implementation));
     }
 
+    @Override
     public BindingBuilder<T> to(Key<? extends T> linkedKey) {
         checkNotNull(linkedKey, "linkedKey");
         checkNotTargetted();
@@ -56,6 +61,7 @@ public class BindingBuilder<T> extends AbstractBindingBuilder<T>
         return this;
     }
 
+    @Override
     public void toInstance(T instance) {
         checkNotTargetted();
 
@@ -79,10 +85,12 @@ public class BindingBuilder<T> extends AbstractBindingBuilder<T>
     }
 
     @SuppressWarnings("unchecked")
+    @Override
     public BindingBuilder<T> toProvider(Provider<? extends T> provider) {
         return toProvider((javax.inject.Provider<T>) provider);
     }
 
+    @Override
     public BindingBuilder<T> toProvider(javax.inject.Provider<? extends T> provider) {
         checkNotNull(provider, "provider");
         checkNotTargetted();
@@ -102,16 +110,19 @@ public class BindingBuilder<T> extends AbstractBindingBuilder<T>
         return this;
     }
 
+    @Override
     public BindingBuilder<T> toProvider(
             Class<? extends javax.inject.Provider<? extends T>> providerType) {
         return toProvider(Key.get(providerType));
     }
 
+    @Override
     public BindingBuilder<T> toProvider(
             TypeLiteral<? extends javax.inject.Provider<? extends T>> providerType) {
         return toProvider(Key.get(providerType));
     }
 
+    @Override
     public BindingBuilder<T> toProvider(
             Key<? extends javax.inject.Provider<? extends T>> providerKey) {
         checkNotNull(providerKey, "providerKey");
@@ -123,10 +134,12 @@ public class BindingBuilder<T> extends AbstractBindingBuilder<T>
         return this;
     }
 
+    @Override
     public <S extends T> ScopedBindingBuilder toConstructor(Constructor<S> constructor) {
         return toConstructor(constructor, TypeLiteral.get(constructor.getDeclaringClass()));
     }
 
+    @Override
     public <S extends T> ScopedBindingBuilder toConstructor(Constructor<S> constructor,
                                                             TypeLiteral<? extends S> type) {
         checkNotNull(constructor, "constructor");

src/main/java/com/google/inject/internal/BindingImpl.java

@@ -34,14 +34,17 @@ public abstract class BindingImpl<T> implements Binding<T> {
         this.scoping = scoping;
     }
 
+    @Override
     public Key<T> getKey() {
         return key;
     }
 
+    @Override
     public Object getSource() {
         return source;
     }
 
+    @Override
     public Provider<T> getProvider() {
         if (provider == null) {
             if (injector == null) {
@@ -69,10 +72,12 @@ public abstract class BindingImpl<T> implements Binding<T> {
         return this instanceof InstanceBinding;
     }
 
+    @Override
     public <V> V acceptVisitor(ElementVisitor<V> visitor) {
         return visitor.visit(this);
     }
 
+    @Override
     public <V> V acceptScopingVisitor(BindingScopingVisitor<V> visitor) {
         return scoping.acceptVisitor(visitor);
     }

src/main/java/com/google/inject/internal/BindingProcessor.java

@@ -49,7 +49,7 @@ final class BindingProcessor extends AbstractBindingProcessor {
             return true;
         }
 
-        return command.acceptTargetVisitor(new Processor<T, Boolean>((BindingImpl<T>) command) {
+        return command.acceptTargetVisitor(new Processor<>((BindingImpl<T>) command) {
             @Override
             public Boolean visit(ConstructorBinding<? extends T> binding) {
                 prepareBinding();
@@ -74,11 +74,11 @@ final class BindingProcessor extends AbstractBindingProcessor {
                         // the processor was constructed w/ it
                 Initializable<T> ref = initializer.requestInjection(
                         injector, instance, (Binding<T>) binding, source, injectionPoints);
-                ConstantFactory<? extends T> factory = new ConstantFactory<T>(ref);
+                ConstantFactory<? extends T> factory = new ConstantFactory<>(ref);
-                InternalFactory<? extends T> scopedFactory
+                InternalFactory<? extends T> scopedFactory =
-                        = Scoping.scope(key, injector, factory, source, scoping);
+                        Scoping.scope(key, injector, factory, source, scoping);
-                putBinding(new InstanceBindingImpl<T>(injector, key, source, scopedFactory, injectionPoints,
+                putBinding(new InstanceBindingImpl<>(injector, key, source,
-                        instance));
+                        scopedFactory, injectionPoints, instance));
                 return true;
             }
 
@@ -86,18 +86,22 @@ final class BindingProcessor extends AbstractBindingProcessor {
             public Boolean visit(ProviderInstanceBinding<? extends T> binding) {
                 prepareBinding();
                 javax.inject.Provider<? extends T> provider = binding.getUserSuppliedProvider();
+                if (provider instanceof InternalProviderInstanceBindingImpl.Factory) {
+                      @SuppressWarnings("unchecked")
+                      InternalProviderInstanceBindingImpl.Factory<T> asProviderMethod =
+                                  (InternalProviderInstanceBindingImpl.Factory<T>) provider;
+                      return visitInternalProviderInstanceBindingFactory(asProviderMethod);
+                    }
                 Set<InjectionPoint> injectionPoints = binding.getInjectionPoints();
                 Initializable<? extends javax.inject.Provider<? extends T>> initializable =
-                        initializer.<javax.inject.Provider<? extends T>>requestInjection(
+                        initializer.requestInjection(injector, provider, null, source, injectionPoints);
-                                injector, provider, null, source, injectionPoints);
                 // always visited with Binding<T>
                 @SuppressWarnings("unchecked")
-                InternalFactory<T> factory = new InternalFactoryToInitializableAdapter<T>(
+                InternalFactory<T> factory = new InternalFactoryToInitializableAdapter<>(
                         initializable, source,
                         injector.provisionListenerStore.get((ProviderInstanceBinding<T>) binding));
-                InternalFactory<? extends T> scopedFactory
+                InternalFactory<? extends T> scopedFactory = Scoping.scope(key, injector, factory, source, scoping);
-                        = Scoping.scope(key, injector, factory, source, scoping);
+                putBinding(new ProviderInstanceBindingImpl<>(injector, key, source, scopedFactory, scoping,
-                putBinding(new ProviderInstanceBindingImpl<T>(injector, key, source, scopedFactory, scoping,
                         provider, injectionPoints));
                 return true;
             }
@@ -108,13 +112,13 @@ final class BindingProcessor extends AbstractBindingProcessor {
                 Key<? extends javax.inject.Provider<? extends T>> providerKey = binding.getProviderKey();
                 // always visited with Binding<T>
                 @SuppressWarnings("unchecked")
-                BoundProviderFactory<T> boundProviderFactory = new BoundProviderFactory<T>(
+                BoundProviderFactory<T> boundProviderFactory = new BoundProviderFactory<>(
                         injector, providerKey, source,
                         injector.provisionListenerStore.get((ProviderKeyBinding<T>) binding));
                 bindingData.addCreationListener(boundProviderFactory);
                 InternalFactory<? extends T> scopedFactory = Scoping.scope(
-                        key, injector, (InternalFactory<? extends T>) boundProviderFactory, source, scoping);
+                        key, injector, boundProviderFactory, source, scoping);
-                putBinding(new LinkedProviderBindingImpl<T>(
+                putBinding(new LinkedProviderBindingImpl<>(
                         injector, key, source, scopedFactory, scoping, providerKey));
                 return true;
             }
@@ -126,13 +130,36 @@ final class BindingProcessor extends AbstractBindingProcessor {
                 if (key.equals(linkedKey)) {
                     errors.recursiveBinding();
                 }
-
+                FactoryProxy<T> factory = new FactoryProxy<>(injector, key, linkedKey, source);
-                FactoryProxy<T> factory = new FactoryProxy<T>(injector, key, linkedKey, source);
                 bindingData.addCreationListener(factory);
-                InternalFactory<? extends T> scopedFactory
+                InternalFactory<? extends T> scopedFactory =
-                        = Scoping.scope(key, injector, factory, source, scoping);
+                        Scoping.scope(key, injector, factory, source, scoping);
-                putBinding(
+                putBinding(new LinkedBindingImpl<>(injector, key, source, scopedFactory, scoping, linkedKey));
-                        new LinkedBindingImpl<T>(injector, key, source, scopedFactory, scoping, linkedKey));
+                return true;
+            }
+
+            /** Handle ProviderMethods specially. */
+            private Boolean visitInternalProviderInstanceBindingFactory(
+                    InternalProviderInstanceBindingImpl.Factory<T> provider) {
+                InternalProviderInstanceBindingImpl<T> binding =
+                        new InternalProviderInstanceBindingImpl<>(
+                                injector,
+                                key,
+                                source,
+                                provider,
+                                Scoping.scope(key, injector, provider, source, scoping),
+                                scoping);
+                switch (binding.getInitializationTiming()) {
+                    case DELAYED:
+                        scheduleDelayedInitialization(binding);
+                        break;
+                    case EAGER:
+                        scheduleInitialization(binding);
+                        break;
+                    default:
+                        throw new AssertionError();
+                }
+                putBinding(binding);
                 return true;
             }
 
@@ -172,9 +199,9 @@ final class BindingProcessor extends AbstractBindingProcessor {
     }
 
     private <T> void bindExposed(PrivateElements privateElements, Key<T> key) {
-        ExposedKeyFactory<T> exposedKeyFactory = new ExposedKeyFactory<T>(key, privateElements);
+        ExposedKeyFactory<T> exposedKeyFactory = new ExposedKeyFactory<>(key, privateElements);
         bindingData.addCreationListener(exposedKeyFactory);
-        putBinding(new ExposedBindingImpl<T>(
+        putBinding(new ExposedBindingImpl<>(
                 injector, privateElements.getExposedSource(key), key, exposedKeyFactory, privateElements));
     }
 }

src/main/java/com/google/inject/internal/BoundProviderFactory.java

@@ -6,16 +6,17 @@ import com.google.inject.spi.Dependency;
 
 import javax.inject.Provider;
 
-import static com.google.common.base.Preconditions.checkNotNull;
-
 /**
  * Delegates to a custom factory which is also bound in the injector.
  */
 final class BoundProviderFactory<T> extends ProviderInternalFactory<T> implements CreationListener {
 
-    final Key<? extends javax.inject.Provider<? extends T>> providerKey;
+    private final Key<? extends javax.inject.Provider<? extends T>> providerKey;
+
     private final ProvisionListenerStackCallback<T> provisionCallback;
+
     private final InjectorImpl injector;
+
     private InternalFactory<? extends javax.inject.Provider<? extends T>> providerFactory;
 
     BoundProviderFactory(
@@ -24,11 +25,12 @@ final class BoundProviderFactory<T> extends ProviderInternalFactory<T> implement
             Object source,
             ProvisionListenerStackCallback<T> provisionCallback) {
         super(source);
-        this.provisionCallback = checkNotNull(provisionCallback, "provisionCallback");
+        this.provisionCallback = provisionCallback;
         this.injector = injector;
         this.providerKey = providerKey;
     }
 
+    @Override
     public void notify(Errors errors) {
         try {
             providerFactory = injector.getInternalFactory(providerKey, errors.withSource(source), JitLimitation.NEW_OR_EXISTING_JIT);
@@ -37,25 +39,27 @@ final class BoundProviderFactory<T> extends ProviderInternalFactory<T> implement
         }
     }
 
-    public T get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked)
+    @Override
-            throws ErrorsException {
+    public T get(InternalContext context, Dependency<?> dependency, boolean linked)
+            throws InternalProvisionException {
         context.pushState(providerKey, source);
         try {
-            errors = errors.withSource(providerKey);
+            javax.inject.Provider<? extends T> provider = providerFactory.get(context, dependency, true);
-            javax.inject.Provider<? extends T> provider = providerFactory.get(errors, context, dependency, true);
+            return circularGet(provider, context, dependency, provisionCallback);
-            return circularGet(provider, errors, context, dependency, provisionCallback);
+        } catch (InternalProvisionException ipe) {
+            throw ipe.addSource(providerKey);
         } finally {
             context.popState();
         }
     }
 
     @Override
-    protected T provision(Provider<? extends T> provider, Errors errors, Dependency<?> dependency,
+    protected T provision(Provider<? extends T> provider, Dependency<?> dependency,
-                          ConstructionContext<T> constructionContext) throws ErrorsException {
+                          ConstructionContext<T> constructionContext) throws InternalProvisionException {
         try {
-            return super.provision(provider, errors, dependency, constructionContext);
+            return super.provision(provider, dependency, constructionContext);
         } catch (RuntimeException userException) {
-            throw errors.errorInProvider(userException).toException();
+            throw InternalProvisionException.errorInProvider(userException);
         }
     }
 

src/main/java/com/google/inject/internal/ConstantBindingBuilderImpl.java

@@ -6,7 +6,6 @@ import com.google.inject.Key;
 import com.google.inject.binder.AnnotatedConstantBindingBuilder;
 import com.google.inject.binder.ConstantBindingBuilder;
 import com.google.inject.spi.Element;
-import com.google.inject.spi.InjectionPoint;
 
 import java.lang.annotation.Annotation;
 import java.util.List;
@@ -24,56 +23,69 @@ public final class ConstantBindingBuilderImpl<T>
         super(binder, elements, source, (Key<T>) NULL_KEY);
     }
 
+    @Override
     public ConstantBindingBuilder annotatedWith(Class<? extends Annotation> annotationType) {
         annotatedWithInternal(annotationType);
         return this;
     }
 
+    @Override
     public ConstantBindingBuilder annotatedWith(Annotation annotation) {
         annotatedWithInternal(annotation);
         return this;
     }
 
+    @Override
     public void to(final String value) {
         toConstant(String.class, value);
     }
 
+    @Override
     public void to(final int value) {
         toConstant(Integer.class, value);
     }
 
+    @Override
     public void to(final long value) {
         toConstant(Long.class, value);
     }
 
+    @Override
     public void to(final boolean value) {
         toConstant(Boolean.class, value);
     }
 
+    @Override
     public void to(final double value) {
         toConstant(Double.class, value);
     }
 
+    @Override
     public void to(final float value) {
         toConstant(Float.class, value);
     }
 
+    @Override
     public void to(final short value) {
         toConstant(Short.class, value);
     }
 
+    @Override
     public void to(final char value) {
         toConstant(Character.class, value);
     }
 
+    @Override
     public void to(final byte value) {
         toConstant(Byte.class, value);
     }
 
+    @Override
     public void to(final Class<?> value) {
         toConstant(Class.class, value);
     }
 
+    @Override
     public <E extends Enum<E>> void to(final E value) {
         toConstant(value.getDeclaringClass(), value);
     }
@@ -105,7 +117,7 @@ public final class ConstantBindingBuilderImpl<T>
         }
 
         setBinding(new InstanceBindingImpl<T>(
-                base.getSource(), key, base.getScoping(), ImmutableSet.<InjectionPoint>of(), instanceAsT));
+                base.getSource(), key, base.getScoping(), ImmutableSet.of(), instanceAsT));
     }
 
     @Override

src/main/java/com/google/inject/internal/ConstantFactory.java

@@ -7,15 +7,17 @@ final class ConstantFactory<T> implements InternalFactory<T> {
 
     private final Initializable<T> initializable;
 
-    public ConstantFactory(Initializable<T> initializable) {
+    ConstantFactory(Initializable<T> initializable) {
         this.initializable = initializable;
     }
 
-    public T get(Errors errors, InternalContext context, Dependency dependency, boolean linked)
+    @Override
-            throws ErrorsException {
+    public T get(InternalContext context, Dependency<?> dependency, boolean linked)
-        return initializable.get(errors);
+            throws InternalProvisionException {
+        return initializable.get();
     }
 
+    @Override
     public String toString() {
         return MoreObjects.toStringHelper(ConstantFactory.class)
                 .add("value", initializable)

src/main/java/com/google/inject/internal/ConstructionContext.java

@@ -41,26 +41,26 @@ final class ConstructionContext<T> {
         invocationHandlers = null;
     }
 
-    public Object createProxy(Errors errors, InjectorOptions injectorOptions,
+    public Object createProxy(InjectorOptions injectorOptions,
-                              Class<?> expectedType) throws ErrorsException {
+                              Class<?> expectedType) throws InternalProvisionException {
         if (injectorOptions.disableCircularProxies) {
-            throw errors.circularProxiesDisabled(expectedType).toException();
+            throw InternalProvisionException.circularDependenciesDisabled(expectedType);
         }
         if (!expectedType.isInterface()) {
-            throw errors.cannotSatisfyCircularDependency(expectedType).toException();
+            throw InternalProvisionException.cannotProxyClass(expectedType);
         }
 
         if (invocationHandlers == null) {
-            invocationHandlers = new ArrayList<DelegatingInvocationHandler<T>>();
+            invocationHandlers = new ArrayList<>();
         }
 
-        DelegatingInvocationHandler<T> invocationHandler = new DelegatingInvocationHandler<T>();
+        DelegatingInvocationHandler<T> invocationHandler = new DelegatingInvocationHandler<>();
         invocationHandlers.add(invocationHandler);
 
         ClassLoader classLoader = expectedType.getClass().getClassLoader() != null ?
                 expectedType.getClass().getClassLoader() : ClassLoader.getSystemClassLoader();
         return expectedType.cast(Proxy.newProxyInstance(classLoader,
-                new Class[]{expectedType, CircularDependencyProxy.class}, invocationHandler));
+                new Class<?>[]{expectedType, CircularDependencyProxy.class}, invocationHandler));
     }
 
     public void setProxyDelegates(T delegate) {

src/main/java/com/google/inject/internal/ConstructorBindingImpl.java

@@ -26,10 +26,15 @@ final class ConstructorBindingImpl<T> extends BindingImpl<T>
         implements ConstructorBinding<T>, DelayedInitialize {
 
     private final Factory<T> factory;
+
     private final InjectionPoint constructorInjectionPoint;
 
-    private ConstructorBindingImpl(InjectorImpl injector, Key<T> key, Object source,
+    private ConstructorBindingImpl(InjectorImpl injector,
-                                   InternalFactory<? extends T> scopedFactory, Scoping scoping, Factory<T> factory,
+                                   Key<T> key,
+                                   Object source,
+                                   InternalFactory<? extends T> scopedFactory,
+                                   Scoping scoping,
+                                   Factory<T> factory,
                                    InjectionPoint constructorInjectionPoint) {
         super(injector, key, source, scopedFactory, scoping);
         this.factory = factory;
@@ -53,7 +58,10 @@ final class ConstructorBindingImpl<T> extends BindingImpl<T>
      *                            only succeed if retrieved from a linked binding
      */
     static <T> ConstructorBindingImpl<T> create(InjectorImpl injector, Key<T> key,
-                                                InjectionPoint constructorInjector, Object source, Scoping scoping, Errors errors,
+                                                InjectionPoint constructorInjector,
+                                                Object source,
+                                                Scoping scoping,
+                                                Errors errors,
                                                 boolean failIfNotLinked, boolean failIfNotExplicit)
             throws ErrorsException {
         int numErrors = errors.size();
@@ -65,7 +73,7 @@ final class ConstructorBindingImpl<T> extends BindingImpl<T>
 
         // We can't inject abstract classes.
         if (Modifier.isAbstract(rawType.getModifiers())) {
-            errors.missingImplementation(key);
+            errors.missingImplementationWithHint(key, injector);
         }
 
         // Error: Inner class.
@@ -110,7 +118,7 @@ final class ConstructorBindingImpl<T> extends BindingImpl<T>
     /**
      * Returns true if the inject annotation is on the constructor.
      */
-    private static boolean hasAtInject(Constructor cxtor) {
+    private static boolean hasAtInject(Constructor<?> cxtor) {
         return cxtor.isAnnotationPresent(Inject.class)
                 || cxtor.isAnnotationPresent(javax.inject.Inject.class);
     }
@@ -162,21 +170,25 @@ final class ConstructorBindingImpl<T> extends BindingImpl<T>
         return Dependency.forInjectionPoints(builder.build());
     }
 
+    @Override
     public <V> V acceptTargetVisitor(BindingTargetVisitor<? super T, V> visitor) {
         checkState(factory.constructorInjector != null, "not initialized");
         return visitor.visit(this);
     }
 
+    @Override
     public InjectionPoint getConstructor() {
         checkState(factory.constructorInjector != null, "Binding is not ready");
         return factory.constructorInjector.getConstructionProxy().getInjectionPoint();
     }
 
+    @Override
     public Set<InjectionPoint> getInjectableMembers() {
         checkState(factory.constructorInjector != null, "Binding is not ready");
         return factory.constructorInjector.getInjectableMembers();
     }
 
+    @Override
     public Set<Dependency<?>> getDependencies() {
         return Dependency.forInjectionPoints(new ImmutableSet.Builder<InjectionPoint>()
                 .add(getConstructor())
@@ -241,18 +253,19 @@ final class ConstructorBindingImpl<T> extends BindingImpl<T>
         }
 
         @SuppressWarnings("unchecked")
-        public T get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked)
+        public T get(InternalContext context, Dependency<?> dependency, boolean linked)
-                throws ErrorsException {
+                throws InternalProvisionException {
-            checkState(constructorInjector != null, "Constructor not ready");
+            ConstructorInjector<T> localInjector = constructorInjector;
-
+            if (localInjector == null) {
-            if (failIfNotLinked && !linked) {
+                throw new IllegalStateException("Constructor not ready");
-                throw errors.jitDisabled(key).toException();
+            }
+            if (!linked && failIfNotLinked) {
+                throw InternalProvisionException.jitDisabled(key);
             }
 
             // This may not actually be safe because it could return a super type of T (if that's all the
             // client needs), but it should be OK in practice thanks to the wonders of erasure.
-            return (T) constructorInjector.construct(errors, context,
+            return (T) localInjector.construct(context, dependency, provisionCallback);
-                    dependency.getKey().getTypeLiteral().getRawType(), provisionCallback);
         }
     }
 }

src/main/java/com/google/inject/internal/ConstructorInjector.java

@@ -2,6 +2,7 @@ package com.google.inject.internal;
 
 import com.google.common.collect.ImmutableSet;
 import com.google.inject.internal.ProvisionListenerStackCallback.ProvisionCallback;
+import com.google.inject.spi.Dependency;
 import com.google.inject.spi.InjectionPoint;
 
 import java.lang.reflect.InvocationTargetException;
@@ -40,37 +41,39 @@ final class ConstructorInjector<T> {
      * Construct an instance. Returns {@code Object} instead of {@code T} because
      * it may return a proxy.
      */
-    Object construct(final Errors errors, final InternalContext context,
+    Object construct(final InternalContext context,
-                     Class<?> expectedType,
+                     Dependency<?> dependency,
                      ProvisionListenerStackCallback<T> provisionCallback)
-            throws ErrorsException {
+            throws InternalProvisionException {
         final ConstructionContext<T> constructionContext = context.getConstructionContext(this);
 
         // We have a circular reference between constructors. Return a proxy.
         if (constructionContext.isConstructing()) {
             // TODO (crazybob): if we can't proxy this object, can we proxy the other object?
             return constructionContext.createProxy(
-                    errors, context.getInjectorOptions(), expectedType);
+                    context.getInjectorOptions(), dependency.getKey().getTypeLiteral().getRawType());
         }
 
         // If we're re-entering this factory while injecting fields or methods,
         // return the same instance. This prevents infinite loops.
         T t = constructionContext.getCurrentReference();
         if (t != null) {
+            if (context.getInjectorOptions().disableCircularProxies) {
+                throw InternalProvisionException.circularDependenciesDisabled(
+                        dependency.getKey().getTypeLiteral().getRawType());
+            } else {
                 return t;
             }
+        }
 
         constructionContext.startConstruction();
         try {
             // Optimization: Don't go through the callback stack if we have no listeners.
-            if (!provisionCallback.hasListeners()) {
+            if (provisionCallback == null) {
-                return provision(errors, context, constructionContext);
+                  return provision(context, constructionContext);
             } else {
-                return provisionCallback.provision(errors, context, new ProvisionCallback<T>() {
+                return provisionCallback.provision(context, () ->
-                    public T call() throws ErrorsException {
+                        provision(context, constructionContext));
-                        return provision(errors, context, constructionContext);
-                    }
-                });
             }
         } finally {
             constructionContext.finishConstruction();
@@ -80,12 +83,12 @@ final class ConstructorInjector<T> {
     /**
      * Provisions a new T.
      */
-    private T provision(Errors errors, InternalContext context,
+    private T provision(InternalContext context, ConstructionContext<T> constructionContext)
-                        ConstructionContext<T> constructionContext) throws ErrorsException {
+            throws InternalProvisionException {
         try {
             T t;
             try {
-                Object[] parameters = SingleParameterInjector.getAll(errors, context, parameterInjectors);
+                Object[] parameters = SingleParameterInjector.getAll(context, parameterInjectors);
                 t = constructionProxy.newInstance(parameters);
                 constructionContext.setProxyDelegates(t);
             } finally {
@@ -94,17 +97,17 @@ final class ConstructorInjector<T> {
 
             // Store reference. If an injector re-enters this factory, they'll get the same reference.
             constructionContext.setCurrentReference(t);
-
+            MembersInjectorImpl<T> localMembersInjector = membersInjector;
-            membersInjector.injectMembers(t, errors, context, false);
+            localMembersInjector.injectMembers(t, context, false);
-            membersInjector.notifyListeners(t, errors);
+            localMembersInjector.notifyListeners(t);
 
             return t;
         } catch (InvocationTargetException userException) {
             Throwable cause = userException.getCause() != null
                     ? userException.getCause()
                     : userException;
-            throw errors.withSource(constructionProxy.getInjectionPoint())
+            throw InternalProvisionException.errorInjectingConstructor(cause)
-                    .errorInjectingConstructor(cause).toException();
+                    .addSource(constructionProxy.getInjectionPoint());
         } finally {
             constructionContext.removeCurrentReference();
         }

src/main/java/com/google/inject/internal/ConstructorInjectorStore.java

@@ -8,8 +8,8 @@ import com.google.inject.spi.InjectionPoint;
 final class ConstructorInjectorStore {
     private final InjectorImpl injector;
 
-    private final FailableCache<InjectionPoint, ConstructorInjector<?>> cache
+    private final FailableCache<InjectionPoint, ConstructorInjector<?>> cache =
-            = new FailableCache<InjectionPoint, ConstructorInjector<?>>() {
+            new FailableCache<>() {
         @Override
         protected ConstructorInjector<?> create(InjectionPoint constructorInjector, Errors errors)
                 throws ErrorsException {
@@ -46,12 +46,12 @@ final class ConstructorInjectorStore {
             throws ErrorsException {
         int numErrorsBefore = errors.size();
 
-        SingleParameterInjector<?>[] constructorParameterInjectors
+        SingleParameterInjector<?>[] constructorParameterInjectors =
-                = injector.getParametersInjectors(injectionPoint.getDependencies(), errors);
+                injector.getParametersInjectors(injectionPoint.getDependencies(), errors);
 
         @SuppressWarnings("unchecked") // the injector type agrees with the injection point type
-                MembersInjectorImpl<T> membersInjector = (MembersInjectorImpl<T>) injector.membersInjectorStore
+        MembersInjectorImpl<T> membersInjector = (MembersInjectorImpl<T>)
-                .get(injectionPoint.getDeclaringType(), errors);
+        injector.membersInjectorStore.get(injectionPoint.getDeclaringType(), errors);
 
         ConstructionProxyFactory<T> factory = new DefaultConstructionProxyFactory<T>(injectionPoint);
 

src/main/java/com/google/inject/internal/ContextualCallable.java

@@ -1,5 +0,0 @@
-package com.google.inject.internal;
-
-interface ContextualCallable<T> {
-    T call(InternalContext context) throws ErrorsException;
-}

src/main/java/com/google/inject/internal/CycleDetectingLock.java

@@ -1,7 +1,6 @@
 package com.google.inject.internal;
 
 import com.google.common.base.Preconditions;
-import com.google.common.base.Supplier;
 import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.LinkedHashMultimap;
 import com.google.common.collect.ListMultimap;
@@ -12,7 +11,6 @@ import com.google.common.collect.Multimaps;
 
 import java.util.Collection;
 import java.util.LinkedHashMap;
-import java.util.List;
 import java.util.Map;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
@@ -43,7 +41,7 @@ interface CycleDetectingLock<ID> {
      * In case no cycle is detected performance is O(threads creating singletons),
      * in case cycle is detected performance is O(singleton locks).
      */
-    ListMultimap<Long, ID> lockOrDetectPotentialLocksCycle();
+    ListMultimap<Thread, ID> lockOrDetectPotentialLocksCycle();
 
     /**
      * Unlocks previously locked lock.
@@ -82,7 +80,7 @@ interface CycleDetectingLock<ID> {
          *
          * Guarded by {@code this}.
          */
-        private final Multimap<Long, ReentrantCycleDetectingLock> locksOwnedByThread =
+        private static final Multimap<Thread, ReentrantCycleDetectingLock<?>> locksOwnedByThread =
                 LinkedHashMultimap.create();
         /**
          * Specifies lock that thread is currently waiting on to own it.
@@ -100,22 +98,22 @@ interface CycleDetectingLock<ID> {
          *
          * Guarded by {@code this}.
          */
-        private Map<Long, ReentrantCycleDetectingLock> lockThreadIsWaitingOn = Maps.newHashMap();
+        private static Map<Thread, ReentrantCycleDetectingLock<?>> lockThreadIsWaitingOn = Maps.newHashMap();
 
         /**
          * Creates new lock within this factory context. We can guarantee that locks created by
          * the same factory would not deadlock.
          *
-         * @param newLockId lock id that would be used to report lock cycles if detected
+         * @param userLockId lock id that would be used to report lock cycles if detected
          */
-        CycleDetectingLock<ID> create(ID newLockId) {
+        CycleDetectingLock<ID> create(ID userLockId) {
-            return new ReentrantCycleDetectingLock(newLockId, new ReentrantLock());
+            return new ReentrantCycleDetectingLock<>(this, userLockId, new ReentrantLock());
         }
 
         /**
          * The implementation for {@link CycleDetectingLock}.
          */
-        class ReentrantCycleDetectingLock implements CycleDetectingLock<ID> {
+        static class ReentrantCycleDetectingLock<ID> implements CycleDetectingLock<ID> {
 
             /**
              * Underlying lock used for actual waiting when no potential deadlocks are detected.
@@ -125,50 +123,56 @@ interface CycleDetectingLock<ID> {
              * User id for this lock.
              */
             private final ID userLockId;
+            /** Factory that was used to create this lock. */
+            private final CycleDetectingLockFactory<ID> lockFactory;
             /**
              * Thread id for the thread that owned this lock. Nullable.
              * Guarded by {@code CycleDetectingLockFactory.this}.
              */
-            private Long lockOwnerThreadId = null;
+            private Thread lockOwnerThread = null;
             /**
              * Number of times that thread owned this lock.
              * Guarded by {@code CycleDetectingLockFactory.this}.
              */
             private int lockReentranceCount = 0;
 
-            ReentrantCycleDetectingLock(ID userLockId, Lock lockImplementation) {
+            ReentrantCycleDetectingLock(
+                    CycleDetectingLockFactory<ID> lockFactory, ID userLockId, Lock lockImplementation) {
+                this.lockFactory = lockFactory;
                 this.userLockId = Preconditions.checkNotNull(userLockId, "userLockId");
                 this.lockImplementation = Preconditions.checkNotNull(
                         lockImplementation, "lockImplementation");
             }
 
             @Override
-            public ListMultimap<Long, ID> lockOrDetectPotentialLocksCycle() {
+            public ListMultimap<Thread, ID> lockOrDetectPotentialLocksCycle() {
-                final long currentThreadId = Thread.currentThread().getId();
+                final Thread currentThread = Thread.currentThread();
-                synchronized (CycleDetectingLockFactory.this) {
+                synchronized (CycleDetectingLockFactory.class) {
                     checkState();
-                    ListMultimap<Long, ID> locksInCycle = detectPotentialLocksCycle();
+                    // Add this lock to the waiting map to ensure it is included in any reported lock cycle.
+                    lockThreadIsWaitingOn.put(currentThread, this);
+                    ListMultimap<Thread, ID> locksInCycle = detectPotentialLocksCycle();
                     if (!locksInCycle.isEmpty()) {
+                        // We aren't actually going to wait for this lock, so remove it from the map.
+                        lockThreadIsWaitingOn.remove(currentThread);
                         // potential deadlock is found, we don't try to take this lock
                         return locksInCycle;
                     }
-
-                    lockThreadIsWaitingOn.put(currentThreadId, this);
                 }
 
                 // this may be blocking, but we don't expect it to cause a deadlock
                 lockImplementation.lock();
 
-                synchronized (CycleDetectingLockFactory.this) {
+                synchronized (CycleDetectingLockFactory.class) {
                     // current thread is no longer waiting on this lock
-                    lockThreadIsWaitingOn.remove(currentThreadId);
+                    lockThreadIsWaitingOn.remove(currentThread);
                     checkState();
 
                     // mark it as owned by us
-                    lockOwnerThreadId = currentThreadId;
+                    lockOwnerThread = currentThread;
                     lockReentranceCount++;
                     // add this lock to the list of locks owned by a current thread
-                    locksOwnedByThread.put(currentThreadId, this);
+                    locksOwnedByThread.put(currentThread, this);
                 }
                 // no deadlock is found, locking successful
                 return ImmutableListMultimap.of();
@@ -176,12 +180,12 @@ interface CycleDetectingLock<ID> {
 
             @Override
             public void unlock() {
-                final long currentThreadId = Thread.currentThread().getId();
+                final Thread currentThread = Thread.currentThread();
-                synchronized (CycleDetectingLockFactory.this) {
+                synchronized (CycleDetectingLockFactory.class) {
                     checkState();
-                    Preconditions.checkState(lockOwnerThreadId != null,
+                    Preconditions.checkState(lockOwnerThread != null,
                             "Thread is trying to unlock a lock that is not locked");
-                    Preconditions.checkState(lockOwnerThreadId == currentThreadId,
+                    Preconditions.checkState(lockOwnerThread == currentThread,
                             "Thread is trying to unlock a lock owned by another thread");
 
                     // releasing underlying lock
@@ -191,12 +195,12 @@ interface CycleDetectingLock<ID> {
                     lockReentranceCount--;
                     if (lockReentranceCount == 0) {
                         // we no longer own this lock
-                        lockOwnerThreadId = null;
+                        lockOwnerThread = null;
-                        Preconditions.checkState(locksOwnedByThread.remove(currentThreadId, this),
+                        Preconditions.checkState(locksOwnedByThread.remove(currentThread, this),
                                 "Internal error: Can not find this lock in locks owned by a current thread");
-                        if (locksOwnedByThread.get(currentThreadId).isEmpty()) {
+                        if (locksOwnedByThread.get(currentThread).isEmpty()) {
                             // clearing memory
-                            locksOwnedByThread.removeAll(currentThreadId);
+                            locksOwnedByThread.removeAll(currentThread);
                         }
                     }
                 }
@@ -206,14 +210,14 @@ interface CycleDetectingLock<ID> {
              * Check consistency of an internal state.
              */
             void checkState() throws IllegalStateException {
-                final long currentThreadId = Thread.currentThread().getId();
+                final Thread currentThread = Thread.currentThread();
-                Preconditions.checkState(!lockThreadIsWaitingOn.containsKey(currentThreadId),
+                Preconditions.checkState(!lockThreadIsWaitingOn.containsKey(currentThread),
                         "Internal error: Thread should not be in a waiting thread on a lock now");
-                if (lockOwnerThreadId != null) {
+                if (lockOwnerThread != null) {
                     // check state of a locked lock
                     Preconditions.checkState(lockReentranceCount >= 0,
                             "Internal error: Lock ownership and reentrance count internal states do not match");
-                    Preconditions.checkState(locksOwnedByThread.get(lockOwnerThreadId).contains(this),
+                    Preconditions.checkState(locksOwnedByThread.get(lockOwnerThread).contains(this),
                             "Internal error: Set of locks owned by a current thread and lock "
                                     + "ownership status do not match");
                 } else {
@@ -233,74 +237,80 @@ interface CycleDetectingLock<ID> {
              *
              * @see CycleDetectingLock#lockOrDetectPotentialLocksCycle()
              */
-            private ListMultimap<Long, ID> detectPotentialLocksCycle() {
+            private ListMultimap<Thread, ID> detectPotentialLocksCycle() {
-                final long currentThreadId = Thread.currentThread().getId();
+                final Thread currentThread = Thread.currentThread();
-                if (lockOwnerThreadId == null || lockOwnerThreadId == currentThreadId) {
+                if (lockOwnerThread == null || lockOwnerThread == currentThread) {
                     // if nobody owns this lock, lock cycle is impossible
                     // if a current thread owns this lock, we let Guice to handle it
                     return ImmutableListMultimap.of();
                 }
 
-                ListMultimap<Long, ID> potentialLocksCycle = Multimaps.newListMultimap(
+                ListMultimap<Thread, ID> potentialLocksCycle = Multimaps.newListMultimap(
-                        new LinkedHashMap<Long, Collection<ID>>(),
+                        new LinkedHashMap<>(), Lists::newArrayList);
-                        new Supplier<List<ID>>() {
-                            @Override
-                            public List<ID> get() {
-                                return Lists.newArrayList();
-                            }
-                        });
                 // lock that is a part of a potential locks cycle, starts with current lock
-                ReentrantCycleDetectingLock lockOwnerWaitingOn = this;
+                ReentrantCycleDetectingLock<?> lockOwnerWaitingOn = this;
                 // try to find a dependency path between lock's owner thread and a current thread
-                while (lockOwnerWaitingOn != null && lockOwnerWaitingOn.lockOwnerThreadId != null) {
+                while (lockOwnerWaitingOn != null && lockOwnerWaitingOn.lockOwnerThread != null) {
-                    Long threadOwnerThreadWaits = lockOwnerWaitingOn.lockOwnerThreadId;
+                    Thread threadOwnerThreadWaits = lockOwnerWaitingOn.lockOwnerThread;
                     // in case locks cycle exists lock we're waiting for is part of it
-                    potentialLocksCycle.putAll(threadOwnerThreadWaits,
+                    lockOwnerWaitingOn =
-                            getAllLockIdsAfter(threadOwnerThreadWaits, lockOwnerWaitingOn));
+                            addAllLockIdsAfter(threadOwnerThreadWaits, lockOwnerWaitingOn, potentialLocksCycle);
-
+                    if (threadOwnerThreadWaits == currentThread) {
-                    if (threadOwnerThreadWaits == currentThreadId) {
                         // owner thread depends on current thread, cycle detected
                         return potentialLocksCycle;
                     }
-                    // going for the next thread we wait on indirectly
-                    lockOwnerWaitingOn = lockThreadIsWaitingOn.get(threadOwnerThreadWaits);
                 }
                 // no dependency path from an owner thread to a current thread
                 return ImmutableListMultimap.of();
             }
 
             /**
-             * Return locks owned by a thread after a lock specified, inclusive.
+             * Adds all locks held by the given thread that are after the given lock and then returns the
+             * lock the thread is currently waiting on, if any
              */
-            private List<ID> getAllLockIdsAfter(long threadId, ReentrantCycleDetectingLock lock) {
+            private ReentrantCycleDetectingLock<?> addAllLockIdsAfter(
-                List<ID> ids = Lists.newArrayList();
+                    Thread thread,
+                    ReentrantCycleDetectingLock<?> lock,
+                    ListMultimap<Thread, ID> potentialLocksCycle) {
                 boolean found = false;
-                Collection<ReentrantCycleDetectingLock> ownedLocks = locksOwnedByThread.get(threadId);
+                Collection<ReentrantCycleDetectingLock<?>> ownedLocks = locksOwnedByThread.get(thread);
                 Preconditions.checkNotNull(ownedLocks,
                         "Internal error: No locks were found taken by a thread");
-                for (ReentrantCycleDetectingLock ownedLock : ownedLocks) {
+                for (ReentrantCycleDetectingLock<?> ownedLock : ownedLocks) {
                     if (ownedLock == lock) {
                         found = true;
                     }
-                    if (found) {
+                    if (found && ownedLock.lockFactory == this.lockFactory) {
-                        ids.add(ownedLock.userLockId);
+                        // All locks are stored in a shared map therefore there is no way to
+                        // enforce type safety. We know that our cast is valid as we check for a lock's
+                        // factory. If the lock was generated by the
+                        // same factory it has to have same type as the current lock.
+                        @SuppressWarnings("unchecked")
+                        ID userLockId = (ID) ownedLock.userLockId;
+                        potentialLocksCycle.put(thread, userLockId);
                     }
                 }
-                Preconditions.checkState(found, "Internal error: We can not find locks that "
+                Preconditions.checkState(found,
-                        + "created a cycle that we detected");
+                        "Internal error: We can not find locks that created a cycle that we detected");
-                return ids;
+                ReentrantCycleDetectingLock<?> unownedLock = lockThreadIsWaitingOn.get(thread);
+                // If this thread is waiting for a lock add it to the cycle and return it
+                if (unownedLock != null && unownedLock.lockFactory == this.lockFactory) {
+                    @SuppressWarnings("unchecked")
+                    ID typed = (ID) unownedLock.userLockId;
+                    potentialLocksCycle.put(thread, typed);
+                }
+                return unownedLock;
             }
 
             @Override
             public String toString() {
                 // copy is made to prevent a data race
                 // no synchronization is used, potentially stale data, should be good enough
-                Long localLockOwnerThreadId = this.lockOwnerThreadId;
+                Thread thread = this.lockOwnerThread;
-                if (localLockOwnerThreadId != null) {
+                if (thread != null) {
-                    return String.format("CycleDetectingLock[%s][locked by %s]",
+                    return String.format("%s[%s][locked by %s]", super.toString(), userLockId, thread);
-                            userLockId, localLockOwnerThreadId);
                 } else {
-                    return String.format("CycleDetectingLock[%s][unlocked]", userLockId);
+                    return String.format("%s[%s][unlocked]", super.toString(), userLockId);
                 }
             }
         }

src/main/java/com/google/inject/internal/DeclaredMembers.java

@@ -0,0 +1,81 @@
+package com.google.inject.internal;
+
+import com.google.common.collect.ComparisonChain;
+import com.google.common.collect.Ordering;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+
+/**
+ * Utility class for retrieving declared fields or methods in a particular order, because the JVM
+ * doesn't guarantee ordering for listing declared methods. We don't externally guarantee an
+ * ordering, but having a consistent ordering allows deterministic behavior and simpler tests.
+ */
+public final class DeclaredMembers {
+
+    private DeclaredMembers() {}
+
+    public static Field[] getDeclaredFields(Class<?> type) {
+        Field[] fields = type.getDeclaredFields();
+        Arrays.sort(fields, FIELD_ORDERING);
+        return fields;
+    }
+
+    public static Method[] getDeclaredMethods(Class<?> type) {
+        Method[] methods = type.getDeclaredMethods();
+        Arrays.sort(methods, METHOD_ORDERING);
+        return methods;
+    }
+
+    /**
+     * An ordering suitable for comparing two classes if they are loaded by the same classloader
+     *
+     * <p>Within a single classloader there can only be one class with a given name, so we just
+     * compare the names.
+     */
+    private static final Ordering<Class<?>> CLASS_ORDERING =
+            new Ordering<>() {
+                @Override
+                public int compare(Class<?> o1, Class<?> o2) {
+                    return o1.getName().compareTo(o2.getName());
+                }
+            };
+
+    /**
+     * An ordering suitable for comparing two fields if they are owned by the same class.
+     *
+     * <p>Within a single class it is sufficent to compare the non-generic field signature which
+     * consists of the field name and type.
+     */
+    private static final Ordering<Field> FIELD_ORDERING =
+            new Ordering<>() {
+                @Override
+                public int compare(Field left, Field right) {
+                    return ComparisonChain.start()
+                            .compare(left.getName(), right.getName())
+                            .compare(left.getType(), right.getType(), CLASS_ORDERING)
+                            .result();
+                }
+            };
+
+    /**
+     * An ordering suitable for comparing two methods if they are owned by the same class.
+     *
+     * <p>Within a single class it is sufficient to compare the non-generic method signature which
+     * consists of the name, return type and parameter types.
+     */
+    private static final Ordering<Method> METHOD_ORDERING =
+            new Ordering<>() {
+                @Override
+                public int compare(Method left, Method right) {
+                    return ComparisonChain.start()
+                            .compare(left.getName(), right.getName())
+                            .compare(left.getReturnType(), right.getReturnType(), CLASS_ORDERING)
+                            .compare(
+                                    Arrays.asList(left.getParameterTypes()),
+                                    Arrays.asList(right.getParameterTypes()),
+                                    CLASS_ORDERING.lexicographical())
+                            .result();
+                }
+            };
+}

src/main/java/com/google/inject/internal/DefaultConstructionProxyFactory.java

@@ -24,13 +24,8 @@ final class DefaultConstructionProxyFactory<T> implements ConstructionProxyFacto
         @SuppressWarnings("unchecked") // the injection point is for a constructor of T
         final Constructor<T> constructor = (Constructor<T>) injectionPoint.getMember();
 
-        // Use FastConstructor if the constructor is public.
+        if (!Modifier.isPublic(constructor.getDeclaringClass().getModifiers()) ||
-        if (Modifier.isPublic(constructor.getModifiers())) {
+                !Modifier.isPublic(constructor.getModifiers())) {
-            Class<T> classToConstruct = constructor.getDeclaringClass();
-            if (!Modifier.isPublic(classToConstruct.getModifiers())) {
-                constructor.setAccessible(true);
-            }
-        } else {
             constructor.setAccessible(true);
         }
 
@@ -38,17 +33,17 @@ final class DefaultConstructionProxyFactory<T> implements ConstructionProxyFacto
             public T newInstance(Object... arguments) throws InvocationTargetException {
                 try {
                     return constructor.newInstance(arguments);
-                } catch (InstantiationException e) {
+                } catch (InstantiationException | IllegalAccessException e) {
                     throw new AssertionError(e); // shouldn't happen, we know this is a concrete type
-                } catch (IllegalAccessException e) {
-                    throw new AssertionError(e); // a security manager is blocking us, we're hosed
                 }
             }
 
+            @Override
             public InjectionPoint getInjectionPoint() {
                 return injectionPoint;
             }
 
+            @Override
             public Constructor<T> getConstructor() {
                 return constructor;
             }

src/main/java/com/google/inject/internal/DeferredLookups.java

@@ -32,13 +32,13 @@ final class DeferredLookups implements Lookups {
     }
 
     public <T> Provider<T> getProvider(Key<T> key) {
-        ProviderLookup<T> lookup = new ProviderLookup<T>(key, key);
+        ProviderLookup<T> lookup = new ProviderLookup<>(key, key);
         lookups.add(lookup);
         return lookup.getProvider();
     }
 
     public <T> MembersInjector<T> getMembersInjector(TypeLiteral<T> type) {
-        MembersInjectorLookup<T> lookup = new MembersInjectorLookup<T>(type, type);
+        MembersInjectorLookup<T> lookup = new MembersInjectorLookup<>(type, type);
         lookups.add(lookup);
         return lookup.getMembersInjector();
     }

src/main/java/com/google/inject/internal/Element.java

@@ -1,4 +1,4 @@
-package com.google.inject.multibindings;
+package com.google.inject.internal;
 
 import com.google.inject.BindingAnnotation;
 
@@ -25,7 +25,6 @@ import static java.lang.annotation.RetentionPolicy.RUNTIME;
 
     enum Type {
         MAPBINDER,
-        MULTIBINDER,
+        MULTIBINDER;
-        OPTIONALBINDER;
     }
 }

src/main/java/com/google/inject/internal/EncounterImpl.java

@@ -43,6 +43,7 @@ final class EncounterImpl<T> implements TypeEncounter<T> {
                 : ImmutableSet.copyOf(injectionListeners);
     }
 
+    @Override
     public void register(MembersInjector<? super T> membersInjector) {
         checkState(valid, "Encounters may not be used after hear() returns.");
 
@@ -53,6 +54,7 @@ final class EncounterImpl<T> implements TypeEncounter<T> {
         membersInjectors.add(membersInjector);
     }
 
+    @Override
     public void register(InjectionListener<? super T> injectionListener) {
         checkState(valid, "Encounters may not be used after hear() returns.");
 
@@ -63,35 +65,42 @@ final class EncounterImpl<T> implements TypeEncounter<T> {
         injectionListeners.add(injectionListener);
     }
 
+    @Override
     public void addError(String message, Object... arguments) {
         checkState(valid, "Encounters may not be used after hear() returns.");
         errors.addMessage(message, arguments);
     }
 
+    @Override
     public void addError(Throwable t) {
         checkState(valid, "Encounters may not be used after hear() returns.");
         errors.errorInUserCode(t, "An exception was caught and reported. Message: %s", t.getMessage());
     }
 
+    @Override
     public void addError(Message message) {
         checkState(valid, "Encounters may not be used after hear() returns.");
         errors.addMessage(message);
     }
 
+    @Override
     public <T> Provider<T> getProvider(Key<T> key) {
         checkState(valid, "Encounters may not be used after hear() returns.");
         return lookups.getProvider(key);
     }
 
+    @Override
     public <T> Provider<T> getProvider(Class<T> type) {
         return getProvider(Key.get(type));
     }
 
+    @Override
     public <T> MembersInjector<T> getMembersInjector(TypeLiteral<T> typeLiteral) {
         checkState(valid, "Encounters may not be used after hear() returns.");
         return lookups.getMembersInjector(typeLiteral);
     }
 
+    @Override
     public <T> MembersInjector<T> getMembersInjector(Class<T> type) {
         return getMembersInjector(TypeLiteral.get(type));
     }

src/main/java/com/google/inject/internal/Errors.java

@@ -4,41 +4,33 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Ordering;
+import com.google.common.primitives.Primitives;
+import com.google.inject.Binding;
 import com.google.inject.ConfigurationException;
 import com.google.inject.CreationException;
+import com.google.inject.Injector;
 import com.google.inject.Key;
-import com.google.inject.MembersInjector;
-import com.google.inject.Provider;
-import com.google.inject.Provides;
 import com.google.inject.ProvisionException;
 import com.google.inject.Scope;
 import com.google.inject.TypeLiteral;
-import com.google.inject.internal.util.Classes;
 import com.google.inject.internal.util.SourceProvider;
-import com.google.inject.internal.util.StackTraceElements;
-import com.google.inject.spi.Dependency;
-import com.google.inject.spi.ElementSource;
-import com.google.inject.spi.InjectionListener;
-import com.google.inject.spi.InjectionPoint;
 import com.google.inject.spi.Message;
 import com.google.inject.spi.ScopeBinding;
 import com.google.inject.spi.TypeConverterBinding;
 import com.google.inject.spi.TypeListenerBinding;
 
-import java.io.PrintWriter;
-import java.io.StringWriter;
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
 import java.lang.reflect.Member;
 import java.lang.reflect.Method;
 import java.lang.reflect.Type;
+import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Formatter;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * A collection of error messages. If this type is passed as a method parameter, the method is
@@ -56,43 +48,40 @@ import java.util.concurrent.ConcurrentHashMap;
  */
 public final class Errors {
 
-    private static final Set<Dependency<?>> warnedDependencies =
+    /** When a binding is not found, show at most this many bindings with the same type */
-            Collections.newSetFromMap(new ConcurrentHashMap<Dependency<?>, Boolean>());
+    private static final int MAX_MATCHING_TYPES_REPORTED = 3;
-    private static final String CONSTRUCTOR_RULES =
+
-            "Classes must have either one (and only one) constructor "
+    /** When a binding is not found, show at most this many bindings that have some similarities */
-                    + "annotated with @Inject or a zero-argument constructor that is not private.";
+    private static final int MAX_RELATED_TYPES_REPORTED = 3;
-    private static final Collection<Converter<?>> converters = ImmutableList.of(
+
-            new Converter<Class>(Class.class) {
+    static <T> T checkNotNull(T reference, String name) {
-                @Override
+        if (reference != null) {
-                public String toString(Class c) {
+            return reference;
-                    return c.getName();
         }
-            },
+        NullPointerException npe = new NullPointerException(name);
-            new Converter<Member>(Member.class) {
+        throw new ConfigurationException(ImmutableSet.of(new Message(npe.toString(), npe)));
-                @Override
-                public String toString(Member member) {
-                    return Classes.toString(member);
     }
-            },
+
-            new Converter<Key>(Key.class) {
+    static void checkConfiguration(boolean condition, String format, Object... args) {
-                @Override
+        if (condition) {
-                public String toString(Key key) {
+            return;
-                    if (key.getAnnotationType() != null) {
-                        return key.getTypeLiteral() + " annotated with "
-                                + (key.getAnnotation() != null ? key.getAnnotation() : key.getAnnotationType());
-                    } else {
-                        return key.getTypeLiteral().toString();
         }
+        throw new ConfigurationException(ImmutableSet.of(new Message(Messages.format(format, args))));
     }
-            });
+
-    /**
+    private static final ImmutableSet<Class<?>> COMMON_AMBIGUOUS_TYPES =
-     * The root errors object. Used to access the list of error messages.
+            ImmutableSet.<Class<?>>builder()
-     */
+                    .add(Object.class)
+                    .add(String.class)
+                    .addAll(Primitives.allWrapperTypes())
+                    .build();
+
+    /** The root errors object. Used to access the list of error messages. */
     private final Errors root;
-    /**
+
-     * The parent errors object. Used to obtain the chain of source objects.
+    /** The parent errors object. Used to obtain the chain of source objects. */
-     */
     private final Errors parent;
+
     /**
      * The leaf source for errors added here.
      */
@@ -120,246 +109,101 @@ public final class Errors {
         this.source = source;
     }
 
-    public static Collection<Message> getMessagesFromThrowable(Throwable throwable) {
+    /** Returns an instance that uses {@code source} as a reference point for newly added errors. */
-        if (throwable instanceof ProvisionException) {
-            return ((ProvisionException) throwable).getErrorMessages();
-        } else if (throwable instanceof ConfigurationException) {
-            return ((ConfigurationException) throwable).getErrorMessages();
-        } else if (throwable instanceof CreationException) {
-            return ((CreationException) throwable).getErrorMessages();
-        } else {
-            return ImmutableSet.of();
-        }
-    }
-
-    public static String format(String messageFormat, Object... arguments) {
-        for (int i = 0; i < arguments.length; i++) {
-            arguments[i] = Errors.convert(arguments[i]);
-        }
-        return String.format(messageFormat, arguments);
-    }
-
-    /**
-     * Returns the formatted message for an exception with the specified messages.
-     */
-    public static String format(String heading, Collection<Message> errorMessages) {
-        Formatter fmt = new Formatter().format(heading).format(":%n%n");
-        int index = 1;
-        boolean displayCauses = getOnlyCause(errorMessages) == null;
-
-        for (Message errorMessage : errorMessages) {
-            fmt.format("%s) %s%n", index++, errorMessage.getMessage());
-
-            List<Object> dependencies = errorMessage.getSources();
-            for (int i = dependencies.size() - 1; i >= 0; i--) {
-                Object source = dependencies.get(i);
-                formatSource(fmt, source);
-            }
-
-            Throwable cause = errorMessage.getCause();
-            if (displayCauses && cause != null) {
-                StringWriter writer = new StringWriter();
-                cause.printStackTrace(new PrintWriter(writer));
-                fmt.format("Caused by: %s", writer.getBuffer());
-            }
-
-            fmt.format("%n");
-        }
-
-        if (errorMessages.size() == 1) {
-            fmt.format("1 error");
-        } else {
-            fmt.format("%s errors", errorMessages.size());
-        }
-
-        return fmt.toString();
-    }
-
-    /**
-     * Returns the cause throwable if there is exactly one cause in {@code messages}. If there are
-     * zero or multiple messages with causes, null is returned.
-     */
-    public static Throwable getOnlyCause(Collection<Message> messages) {
-        Throwable onlyCause = null;
-        for (Message message : messages) {
-            Throwable messageCause = message.getCause();
-            if (messageCause == null) {
-                continue;
-            }
-
-            if (onlyCause != null) {
-                return null;
-            }
-
-            onlyCause = messageCause;
-        }
-
-        return onlyCause;
-    }
-
-    public static Object convert(Object o) {
-        ElementSource source = null;
-        if (o instanceof ElementSource) {
-            source = (ElementSource) o;
-            o = source.getDeclaringSource();
-        }
-        return convert(o, source);
-    }
-
-    public static Object convert(Object o, ElementSource source) {
-        for (Converter<?> converter : converters) {
-            if (converter.appliesTo(o)) {
-                return appendModules(converter.convert(o), source);
-            }
-        }
-        return appendModules(o, source);
-    }
-
-    private static Object appendModules(Object source, ElementSource elementSource) {
-        String modules = moduleSourceString(elementSource);
-        if (modules.length() == 0) {
-            return source;
-        } else {
-            return source + modules;
-        }
-    }
-
-    private static String moduleSourceString(ElementSource elementSource) {
-        // if we only have one module (or don't know what they are), then don't bother
-        // reporting it, because the source already is going to report exactly that module.
-        if (elementSource == null) {
-            return "";
-        }
-        List<String> modules = Lists.newArrayList(elementSource.getModuleClassNames());
-        // Insert any original element sources w/ module info into the path.
-        while (elementSource.getOriginalElementSource() != null) {
-            elementSource = elementSource.getOriginalElementSource();
-            modules.addAll(0, elementSource.getModuleClassNames());
-        }
-        if (modules.size() <= 1) {
-            return "";
-        }
-
-        // Ideally we'd do:
-        //    return Joiner.on(" -> ")
-        //        .appendTo(new StringBuilder(" (via modules: "), Lists.reverse(modules))
-        //        .append(")").toString();
-        // ... but for some reason we can't find Lists.reverse, so do it the boring way.
-        StringBuilder builder = new StringBuilder(" (via modules: ");
-        for (int i = modules.size() - 1; i >= 0; i--) {
-            builder.append(modules.get(i));
-            if (i != 0) {
-                builder.append(" -> ");
-            }
-        }
-        builder.append(")");
-        return builder.toString();
-    }
-
-    public static void formatSource(Formatter formatter, Object source) {
-        ElementSource elementSource = null;
-        if (source instanceof ElementSource) {
-            elementSource = (ElementSource) source;
-            source = elementSource.getDeclaringSource();
-        }
-        formatSource(formatter, source, elementSource);
-    }
-
-    public static void formatSource(Formatter formatter, Object source, ElementSource elementSource) {
-        String modules = moduleSourceString(elementSource);
-        if (source instanceof Dependency) {
-            Dependency<?> dependency = (Dependency<?>) source;
-            InjectionPoint injectionPoint = dependency.getInjectionPoint();
-            if (injectionPoint != null) {
-                formatInjectionPoint(formatter, dependency, injectionPoint, elementSource);
-            } else {
-                formatSource(formatter, dependency.getKey(), elementSource);
-            }
-
-        } else if (source instanceof InjectionPoint) {
-            formatInjectionPoint(formatter, null, (InjectionPoint) source, elementSource);
-
-        } else if (source instanceof Class) {
-            formatter.format("  at %s%s%n", StackTraceElements.forType((Class<?>) source), modules);
-
-        } else if (source instanceof Member) {
-            formatter.format("  at %s%s%n", StackTraceElements.forMember((Member) source), modules);
-
-        } else if (source instanceof TypeLiteral) {
-            formatter.format("  while locating %s%s%n", source, modules);
-
-        } else if (source instanceof Key) {
-            Key<?> key = (Key<?>) source;
-            formatter.format("  while locating %s%n", convert(key, elementSource));
-
-        } else if (source instanceof Thread) {
-            formatter.format("  in thread %s%n", source);
-
-        } else {
-            formatter.format("  at %s%s%n", source, modules);
-        }
-    }
-
-    public static void formatInjectionPoint(Formatter formatter, Dependency<?> dependency,
-                                            InjectionPoint injectionPoint, ElementSource elementSource) {
-        Member member = injectionPoint.getMember();
-        Class<? extends Member> memberType = Classes.memberType(member);
-
-        if (memberType == Field.class) {
-            dependency = injectionPoint.getDependencies().get(0);
-            formatter.format("  while locating %s%n", convert(dependency.getKey(), elementSource));
-            formatter.format("    for field at %s%n", StackTraceElements.forMember(member));
-
-        } else if (dependency != null) {
-            formatter.format("  while locating %s%n", convert(dependency.getKey(), elementSource));
-            formatter.format("    for parameter %s at %s%n",
-                    dependency.getParameterIndex(), StackTraceElements.forMember(member));
-
-        } else {
-            formatSource(formatter, injectionPoint.getMember());
-        }
-    }
-
-    /**
-     * Returns an instance that uses {@code source} as a reference point for newly added errors.
-     */
     public Errors withSource(Object source) {
         return source == this.source || source == SourceProvider.UNKNOWN_SOURCE
                 ? this
                 : new Errors(this, source);
     }
 
-    /**
+    public Errors missingImplementation(Key<?> key) {
-     * We use a fairly generic error message here. The motivation is to share the
-     * same message for both bind time errors:
-     * <pre><code>Guice.createInjector(new AbstractModule() {
-     *   public void configure() {
-     *     bind(Runnable.class);
-     *   }
-     * }</code></pre>
-     * ...and at provide-time errors:
-     * <pre><code>Guice.createInjector().getInstance(Runnable.class);</code></pre>
-     * Otherwise we need to know who's calling when resolving a just-in-time
-     * binding, which makes things unnecessarily complex.
-     */
-    public Errors missingImplementation(Key key) {
         return addMessage("No implementation for %s was bound.", key);
     }
 
-    public Errors jitDisabled(Key key) {
+    /** Within guice's core, allow for better missing binding messages */
+    <T> Errors missingImplementationWithHint(Key<T> key, Injector injector) {
+        StringBuilder sb = new StringBuilder();
+
+        sb.append(Messages.format("No implementation for %s was bound.", key));
+
+        // Keys which have similar strings as the desired key
+        List<String> possibleMatches = new ArrayList<>();
+
+        // Check for other keys that may have the same type,
+        // but not the same annotation
+        TypeLiteral<T> type = key.getTypeLiteral();
+        List<Binding<T>> sameTypes = injector.findBindingsByType(type);
+        if (!sameTypes.isEmpty()) {
+            sb.append(Messages.format("%n  Did you mean?"));
+            int howMany = Math.min(sameTypes.size(), MAX_MATCHING_TYPES_REPORTED);
+            for (int i = 0; i < howMany; ++i) {
+                // TODO: Look into a better way to prioritize suggestions. For example, possbily
+                // use levenshtein distance of the given annotation vs actual annotation.
+                sb.append(Messages.format("%n    * %s", sameTypes.get(i).getKey()));
+            }
+            int remaining = sameTypes.size() - MAX_MATCHING_TYPES_REPORTED;
+            if (remaining > 0) {
+                String plural = (remaining == 1) ? "" : "s";
+                sb.append(Messages.format("%n    %d more binding%s with other annotations.", remaining, plural));
+            }
+        } else {
+            // For now, do a simple substring search for possibilities. This can help spot
+            // issues when there are generics being used (such as a wrapper class) and the
+            // user has forgotten they need to bind based on the wrapper, not the underlying
+            // class. In the future, consider doing a strict in-depth type search.
+            // TODO: Look into a better way to prioritize suggestions. For example, possbily
+            // use levenshtein distance of the type literal strings.
+            String want = type.toString();
+            Map<Key<?>, Binding<?>> bindingMap = injector.getAllBindings();
+            for (Key<?> bindingKey : bindingMap.keySet()) {
+                String have = bindingKey.getTypeLiteral().toString();
+                if (have.contains(want) || want.contains(have)) {
+                    Formatter fmt = new Formatter();
+                    Messages.formatSource(fmt, bindingMap.get(bindingKey).getSource());
+                    String match = String.format("%s bound%s", Messages.convert(bindingKey), fmt.toString());
+                    possibleMatches.add(match);
+                    // TODO: Consider a check that if there are more than some number of results,
+                    // don't suggest any.
+                    if (possibleMatches.size() > MAX_RELATED_TYPES_REPORTED) {
+                        // Early exit if we have found more than we need.
+                        break;
+                    }
+                }
+            }
+
+            if ((possibleMatches.size() > 0) && (possibleMatches.size() <= MAX_RELATED_TYPES_REPORTED)) {
+                sb.append(Messages.format("%n  Did you mean?"));
+                for (String possibleMatch : possibleMatches) {
+                    sb.append(Messages.format("%n    %s", possibleMatch));
+                }
+            }
+        }
+
+        // If where are no possibilities to suggest, then handle the case of missing
+        // annotations on simple types. This is usually a bad idea.
+        if (sameTypes.isEmpty()
+                && possibleMatches.isEmpty()
+                && key.getAnnotationType() == null
+                && COMMON_AMBIGUOUS_TYPES.contains(key.getTypeLiteral().getRawType())) {
+            // We don't recommend using such simple types without annotations.
+            sb.append(Messages.format("%nThe key seems very generic, did you forget an annotation?"));
+        }
+
+        return addMessage(sb.toString());
+    }
+
+    public Errors jitDisabled(Key<?> key) {
         return addMessage("Explicit bindings are required and %s is not explicitly bound.", key);
     }
 
     public Errors jitDisabledInParent(Key<?> key) {
-        return addMessage(
+        return addMessage("Explicit bindings are required and %s would be bound in a parent injector.%n"
-                "Explicit bindings are required and %s would be bound in a parent injector.%n"
                         + "Please add an explicit binding for it, either in the child or the parent.",
                 key);
     }
 
-    public Errors atInjectRequired(Class clazz) {
+    public Errors atInjectRequired(Class<?> clazz) {
-        return addMessage(
+        return addMessage("Explicit @Inject annotations are required on constructors,"
-                "Explicit @Inject annotations are required on constructors,"
                         + " but %s has no constructors annotated with @Inject.",
                 clazz);
     }
@@ -368,7 +212,7 @@ public final class Errors {
                                         TypeLiteral<?> type, TypeConverterBinding typeConverterBinding) {
         return addMessage("Received null converting '%s' (bound at %s) to %s%n"
                         + " using %s.",
-                stringValue, convert(source), type, typeConverterBinding);
+                stringValue, Messages.convert(source), type, typeConverterBinding);
     }
 
     public Errors conversionTypeError(String stringValue, Object source, TypeLiteral<?> type,
@@ -376,7 +220,7 @@ public final class Errors {
         return addMessage("Type mismatch converting '%s' (bound at %s) to %s%n"
                         + " using %s.%n"
                         + " Converter returned %s.",
-                stringValue, convert(source), type, typeConverterBinding, converted);
+                stringValue, Messages.convert(source), type, typeConverterBinding, converted);
     }
 
     public Errors conversionError(String stringValue, Object source,
@@ -384,7 +228,7 @@ public final class Errors {
         return errorInUserCode(cause, "Error converting '%s' (bound at %s) to %s%n"
                         + " using %s.%n"
                         + " Reason: %s",
-                stringValue, convert(source), type, typeConverterBinding, cause);
+                stringValue, Messages.convert(source), type, typeConverterBinding, cause);
     }
 
     public Errors ambiguousTypeConversion(String stringValue, Object source, TypeLiteral<?> type,
@@ -393,18 +237,13 @@ public final class Errors {
                         + " %s and%n"
                         + " %s.%n"
                         + " Please adjust your type converter configuration to avoid overlapping matches.",
-                stringValue, convert(source), type, a, b);
+                stringValue, Messages.convert(source), type, a, b);
     }
 
     public Errors bindingToProvider() {
         return addMessage("Binding to Provider is not allowed.");
     }
 
-    public Errors subtypeNotProvided(Class<? extends Provider<?>> providerType,
-                                     Class<?> type) {
-        return addMessage("%s doesn't provide instances of %s.", providerType, type);
-    }
-
     public Errors notASubtype(Class<?> implementationType, Class<?> type) {
         return addMessage("%s doesn't extend %s.", implementationType, type);
     }
@@ -418,14 +257,14 @@ public final class Errors {
     }
 
     public Errors missingRuntimeRetention(Class<? extends Annotation> annotation) {
-        return addMessage(format("Please annotate %s with @Retention(RUNTIME).", annotation));
+        return addMessage(Messages.format("Please annotate %s with @Retention(RUNTIME).", annotation));
     }
 
     public Errors missingScopeAnnotation(Class<? extends Annotation> annotation) {
-        return addMessage(format("Please annotate %s with @ScopeAnnotation.", annotation));
+        return addMessage(Messages.format("Please annotate %s with @ScopeAnnotation.", annotation));
     }
 
-    public Errors optionalConstructor(Constructor constructor) {
+    public Errors optionalConstructor(Constructor<?> constructor) {
         return addMessage("%s is annotated @Inject(optional=true), "
                 + "but constructors cannot be optional.", constructor);
     }
@@ -441,7 +280,7 @@ public final class Errors {
     public Errors scopeAnnotationOnAbstractType(
             Class<? extends Annotation> scopeAnnotation, Class<?> type, Object source) {
         return addMessage("%s is annotated with %s, but scope annotations are not supported "
-                + "for abstract types.%n Bound at %s.", type, scopeAnnotation, convert(source));
+                + "for abstract types.%n Bound at %s.", type, scopeAnnotation, Messages.convert(source));
     }
 
     public Errors misplacedBindingAnnotation(Member member, Annotation bindingAnnotation) {
@@ -449,14 +288,27 @@ public final class Errors {
                 + "to its parameters instead.", member, bindingAnnotation);
     }
 
-    public Errors missingConstructor(Class<?> implementation) {
+    private static final String CONSTRUCTOR_RULES =
-        return addMessage("Could not find a suitable constructor in %s. " + CONSTRUCTOR_RULES,
+            "Injectable classes must have either one (and only one) constructor annotated with @Inject"
-                implementation);
+                    + " or a zero-argument constructor that is not private.";
+
+    public Errors missingConstructor(TypeLiteral<?> type) {
+        // Don't bother including the type in the message twice, unless the type is generic (i.e. the
+        // type has generics that the raw class loses)
+        String typeString = type.toString();
+        String rawTypeString = MoreTypes.getRawType(type.getType()).getName();
+        return addMessage(
+                "No implementation for %s (with no qualifier annotation) was bound, and could not find an"
+                        + " injectable constructor%s. %s",
+                typeString,
+                typeString.equals(rawTypeString) ? "" : " in " + rawTypeString,
+                CONSTRUCTOR_RULES);
     }
 
     public Errors tooManyConstructors(Class<?> implementation) {
-        return addMessage("%s has more than one constructor annotated with @Inject. "
+        return addMessage(
-                + CONSTRUCTOR_RULES, implementation);
+                "%s has more than one constructor annotated with @Inject. %s",
+                implementation, CONSTRUCTOR_RULES);
     }
 
     public Errors constructorNotDefinedByType(Constructor<?> constructor, TypeLiteral<?> type) {
@@ -518,7 +370,7 @@ public final class Errors {
     }
 
     public Errors bindingAlreadySet(Key<?> key, Object source) {
-        return addMessage("A binding to %s was already configured at %s.", key, convert(source));
+        return addMessage("A binding to %s was already configured at %s.", key, Messages.convert(source));
     }
 
     public Errors jitBindingAlreadySet(Key<?> key) {
@@ -534,24 +386,19 @@ public final class Errors {
                 allSources.format("%n    bound at %s", source);
             }
         }
-        Errors errors = addMessage(
+        return addMessage(
                 "Unable to create binding for %s."
                         + " It was already configured on one or more child injectors or private modules"
                         + "%s%n"
                         + "  If it was in a PrivateModule, did you forget to expose the binding?",
                 key, allSources.out());
-        return errors;
     }
 
     public Errors errorCheckingDuplicateBinding(Key<?> key, Object source, Throwable t) {
         return addMessage(
                 "A binding to %s was already configured at %s and an error was thrown "
                         + "while checking duplicate bindings.  Error: %s",
-                key, convert(source), t);
+                key, Messages.convert(source), t);
-    }
-
-    public Errors errorInjectingMethod(Throwable cause) {
-        return errorInUserCode(cause, "Error injecting method, %s", cause);
     }
 
     public Errors errorNotifyingTypeListener(TypeListenerBinding listener,
@@ -559,28 +406,7 @@ public final class Errors {
         return errorInUserCode(cause,
                 "Error notifying TypeListener %s (bound at %s) of %s.%n"
                         + " Reason: %s",
-                listener.getListener(), convert(listener.getSource()), type, cause);
+                listener.getListener(), Messages.convert(listener.getSource()), type, cause);
-    }
-
-    public Errors errorInjectingConstructor(Throwable cause) {
-        return errorInUserCode(cause, "Error injecting constructor, %s", cause);
-    }
-
-    public Errors errorInProvider(RuntimeException runtimeException) {
-        Throwable unwrapped = unwrap(runtimeException);
-        return errorInUserCode(unwrapped, "Error in custom provider, %s", unwrapped);
-    }
-
-    public Errors errorInUserInjector(
-            MembersInjector<?> listener, TypeLiteral<?> type, RuntimeException cause) {
-        return errorInUserCode(cause, "Error injecting %s using %s.%n"
-                + " Reason: %s", type, listener, cause);
-    }
-
-    public Errors errorNotifyingInjectionListener(
-            InjectionListener<?> listener, TypeLiteral<?> type, RuntimeException cause) {
-        return errorInUserCode(cause, "Error notifying InjectionListener %s of %s.%n"
-                + " Reason: %s", listener, type, cause);
     }
 
     public Errors exposedButNotBound(Key<?> key) {
@@ -595,6 +421,18 @@ public final class Errors {
         return errorInUserCode(cause, "Unable to method intercept: %s", clazz);
     }
 
+    public static Collection<Message> getMessagesFromThrowable(Throwable throwable) {
+        if (throwable instanceof ProvisionException) {
+            return ((ProvisionException) throwable).getErrorMessages();
+        } else if (throwable instanceof ConfigurationException) {
+            return ((ConfigurationException) throwable).getErrorMessages();
+        } else if (throwable instanceof CreationException) {
+            return ((CreationException) throwable).getErrorMessages();
+        } else {
+            return ImmutableSet.of();
+        }
+    }
+
     public Errors errorInUserCode(Throwable cause, String messageFormat, Object... arguments) {
         Collection<Message> messages = getMessagesFromThrowable(cause);
 
@@ -605,13 +443,6 @@ public final class Errors {
         }
     }
 
-    private Throwable unwrap(RuntimeException runtimeException) {
-        if (runtimeException instanceof Exceptions.UnhandledCheckedUserException) {
-            return runtimeException.getCause();
-        } else {
-            return runtimeException;
-        }
-    }
 
     public Errors cannotInjectRawProvider() {
         return addMessage("Cannot inject a Provider that has no type parameter");
@@ -629,23 +460,10 @@ public final class Errors {
         return addMessage("Cannot inject a TypeLiteral that has no type parameter");
     }
 
-    public Errors cannotSatisfyCircularDependency(Class<?> expectedType) {
-        return addMessage(
-                "Tried proxying %s to support a circular dependency, but it is not an interface.",
-                expectedType);
-    }
-
-    public Errors circularProxiesDisabled(Class<?> expectedType) {
-        return addMessage(
-                "Tried proxying %s to support a circular dependency, but circular proxies are disabled.",
-                expectedType);
-    }
-
     public void throwCreationExceptionIfErrorsExist() {
         if (!hasErrors()) {
             return;
         }
-
         throw new CreationException(getMessages());
     }
 
@@ -653,28 +471,13 @@ public final class Errors {
         if (!hasErrors()) {
             return;
         }
-
         throw new ConfigurationException(getMessages());
     }
 
-    public void throwProvisionExceptionIfErrorsExist() {
-        if (!hasErrors()) {
-            return;
-        }
-
-        throw new ProvisionException(getMessages());
-    }
-
-    private Message merge(Message message) {
-        List<Object> sources = Lists.newArrayList();
-        sources.addAll(getSources());
-        sources.addAll(message.getSources());
-        return new Message(sources, message.getMessage(), message.getCause());
-    }
-
     public Errors merge(Collection<Message> messages) {
+        List<Object> sources = getSources();
         for (Message message : messages) {
-            addMessage(merge(message));
+            addMessage(Messages.mergeSources(sources, message));
         }
         return this;
     }
@@ -683,11 +486,15 @@ public final class Errors {
         if (moreErrors.root == root || moreErrors.root.errors == null) {
             return this;
         }
-
         merge(moreErrors.root.errors);
         return this;
     }
 
+    public Errors merge(InternalProvisionException ipe) {
+        merge(ipe.getErrors());
+        return this;
+    }
+
     public List<Object> getSources() {
         List<Object> sources = Lists.newArrayList();
         for (Errors e = this; e != null; e = e.parent) {
@@ -719,8 +526,7 @@ public final class Errors {
     }
 
     private Errors addMessage(Throwable cause, String messageFormat, Object... arguments) {
-        String message = format(messageFormat, arguments);
+        addMessage(Messages.create(cause, getSources(), messageFormat, arguments));
-        addMessage(new Message(getSources(), message, cause));
         return this;
     }
 
@@ -736,7 +542,6 @@ public final class Errors {
         if (root.errors == null) {
             return ImmutableList.of();
         }
-
         return new Ordering<Message>() {
             @Override
             public int compare(Message a, Message b) {
@@ -745,73 +550,7 @@ public final class Errors {
         }.sortedCopy(root.errors);
     }
 
-    /**
-     * Returns {@code value} if it is non-null allowed to be null. Otherwise a message is added and
-     * an {@code ErrorsException} is thrown.
-     */
-    public <T> T checkForNull(T value, Object source, Dependency<?> dependency)
-            throws ErrorsException {
-        if (value != null || dependency.isNullable()) {
-            return value;
-        }
-
-        // Hack to allow null parameters to @Provides methods, for backwards compatibility.
-        if (dependency.getInjectionPoint().getMember() instanceof Method) {
-            Method annotated = (Method) dependency.getInjectionPoint().getMember();
-            if (annotated.isAnnotationPresent(Provides.class)) {
-                switch (InternalFlags.getNullableProvidesOption()) {
-                    case ERROR:
-                        break; // break out & let the below exception happen
-                    case IGNORE:
-                        return value; // user doesn't care about injecting nulls to non-@Nullables.
-                    case WARN:
-                        // Warn only once, otherwise we spam logs too much.
-                        if (!warnedDependencies.add(dependency)) {
-                            return value;
-                        }
-                        /*logger.log(Level.WARNING,
-                                "Guice injected null into parameter {0} of {1} (a {2}), please mark it @Nullable."
-                                        + " Use -Dguice_check_nullable_provides_params=ERROR to turn this into an"
-                                        + " error.",
-                                new Object[]{
-                                        dependency.getParameterIndex(),
-                                        convert(dependency.getInjectionPoint().getMember()),
-                                        convert(dependency.getKey())});*/
-                        return null; // log & exit.
-                }
-            }
-        }
-
-        int parameterIndex = dependency.getParameterIndex();
-        String parameterName = (parameterIndex != -1)
-                ? "parameter " + parameterIndex + " of "
-                : "";
-        addMessage("null returned by binding at %s%n but %s%s is not @Nullable",
-                source, parameterName, dependency.getInjectionPoint().getMember());
-
-        throw toException();
-    }
-
     public int size() {
         return root.errors == null ? 0 : root.errors.size();
     }
-
-    private static abstract class Converter<T> {
-
-        final Class<T> type;
-
-        Converter(Class<T> type) {
-            this.type = type;
-        }
-
-        boolean appliesTo(Object o) {
-            return o != null && type.isAssignableFrom(o.getClass());
-        }
-
-        String convert(Object o) {
-            return toString(type.cast(o));
-        }
-
-        abstract String toString(T t);
-    }
 }

src/main/java/com/google/inject/internal/ErrorsException.java

@@ -8,6 +8,9 @@ package com.google.inject.internal;
 @SuppressWarnings("serial")
 public class ErrorsException extends Exception {
 
+    // NOTE: this is used by Gin which is abandoned.  So changing this API will prevent Gin users from
+    // upgrading Guice version.
+
     private final Errors errors;
 
     public ErrorsException(Errors errors) {

src/main/java/com/google/inject/internal/Exceptions.java

@@ -1,46 +0,0 @@
-package com.google.inject.internal;
-
-/**
- * Rethrows user-code exceptions in wrapped exceptions so that Errors can target the correct
- * exception.
- */
-class Exceptions {
-
-    /**
-     * Rethrows the exception (or it's cause, if it has one) directly if possible.
-     * If it was a checked exception, this wraps the exception in a stack trace
-     * with no frames, so that the exception is shown immediately with no frames
-     * above it.
-     */
-    public static RuntimeException rethrowCause(Throwable throwable) {
-        Throwable cause = throwable;
-        if (cause.getCause() != null) {
-            cause = cause.getCause();
-        }
-        return rethrow(cause);
-    }
-
-    /**
-     * Rethrows the exception.
-     */
-    public static RuntimeException rethrow(Throwable throwable) {
-        if (throwable instanceof RuntimeException) {
-            throw (RuntimeException) throwable;
-        } else if (throwable instanceof Error) {
-            throw (Error) throwable;
-        } else {
-            throw new UnhandledCheckedUserException(throwable);
-        }
-    }
-
-    /**
-     * A marker exception class that we look for in order to unwrap the exception
-     * into the user exception, to provide a cleaner stack trace.
-     */
-    @SuppressWarnings("serial")
-    static class UnhandledCheckedUserException extends RuntimeException {
-        public UnhandledCheckedUserException(Throwable cause) {
-            super(cause);
-        }
-    }
-}

src/main/java/com/google/inject/internal/ExposedBindingImpl.java

@@ -22,14 +22,17 @@ public final class ExposedBindingImpl<T> extends BindingImpl<T> implements Expos
         this.privateElements = privateElements;
     }
 
+    @Override
     public <V> V acceptTargetVisitor(BindingTargetVisitor<? super T, V> visitor) {
         return visitor.visit(this);
     }
 
+    @Override
     public Set<Dependency<?>> getDependencies() {
         return ImmutableSet.<Dependency<?>>of(Dependency.get(Key.get(Injector.class)));
     }
 
+    @Override
     public PrivateElements getPrivateElements() {
         return privateElements;
     }

src/main/java/com/google/inject/internal/ExposedKeyFactory.java

@@ -18,6 +18,7 @@ final class ExposedKeyFactory<T> implements InternalFactory<T>, CreationListener
         this.privateElements = privateElements;
     }
 
+    @Override
     public void notify(Errors errors) {
         InjectorImpl privateInjector = (InjectorImpl) privateElements.getInjector();
         BindingImpl<T> explicitBinding = privateInjector.state.getExplicitBinding(key);
@@ -33,8 +34,8 @@ final class ExposedKeyFactory<T> implements InternalFactory<T>, CreationListener
         this.delegate = explicitBinding;
     }
 
-    public T get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked)
+    public T get(InternalContext context, Dependency<?> dependency, boolean linked)
-            throws ErrorsException {
+            throws InternalProvisionException {
-        return delegate.getInternalFactory().get(errors, context, dependency, linked);
+        return delegate.getInternalFactory().get(context, dependency, linked);
     }
 }

src/main/java/com/google/inject/internal/ExposureBuilder.java

@@ -27,12 +27,14 @@ public class ExposureBuilder<T> implements AnnotatedElementBuilder {
         }
     }
 
+    @Override
     public void annotatedWith(Class<? extends Annotation> annotationType) {
         Preconditions.checkNotNull(annotationType, "annotationType");
         checkNotAnnotated();
         key = Key.get(key.getTypeLiteral(), annotationType);
     }
 
+    @Override
     public void annotatedWith(Annotation annotation) {
         Preconditions.checkNotNull(annotation, "annotation");
         checkNotAnnotated();

src/main/java/com/google/inject/internal/FactoryProxy.java

@@ -25,6 +25,7 @@ final class FactoryProxy<T> implements InternalFactory<T>, CreationListener {
         this.source = source;
     }
 
+    @Override
     public void notify(final Errors errors) {
         try {
             targetFactory = injector.getInternalFactory(targetKey, errors.withSource(source), JitLimitation.NEW_OR_EXISTING_JIT);
@@ -33,11 +34,15 @@ final class FactoryProxy<T> implements InternalFactory<T>, CreationListener {
         }
     }
 
-    public T get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked)
+    @Override
-            throws ErrorsException {
+    public T get(InternalContext context, Dependency<?> dependency, boolean linked)
-        context.pushState(targetKey, source);
+            throws InternalProvisionException {
+        Key<? extends T> localTargetKey = targetKey;
+        context.pushState(localTargetKey, source);
         try {
-            return targetFactory.get(errors.withSource(targetKey), context, dependency, true);
+            return targetFactory.get(context, dependency, true);
+        } catch (InternalProvisionException ipe) {
+            throw ipe.addSource(localTargetKey);
         } finally {
             context.popState();
         }

src/main/java/com/google/inject/internal/FailableCache.java

@@ -3,6 +3,9 @@ package com.google.inject.internal;
 import com.google.common.cache.CacheBuilder;
 import com.google.common.cache.CacheLoader;
 import com.google.common.cache.LoadingCache;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Maps;
+import java.util.Map;
 
 /**
  * Lazily creates (and caches) values for keys. If creating the value fails (with errors), an
@@ -10,8 +13,8 @@ import com.google.common.cache.LoadingCache;
  */
 public abstract class FailableCache<K, V> {
 
-    private final LoadingCache<K, Object> delegate = CacheBuilder.newBuilder().build(
+    private final LoadingCache<K, Object> delegate = CacheBuilder.newBuilder()
-            new CacheLoader<K, Object>() {
+            .build(new CacheLoader<>() {
                 public Object load(K key) {
                     Errors errors = new Errors();
                     V result = null;
@@ -41,4 +44,14 @@ public abstract class FailableCache<K, V> {
     boolean remove(K key) {
         return delegate.asMap().remove(key) != null;
     }
+
+    Map<K, V> asMap() {
+        return Maps.transformValues(Maps.filterValues(ImmutableMap.copyOf(delegate.asMap()),
+                        resultOrError -> !(resultOrError instanceof Errors)),
+                resultOrError -> {
+                    @SuppressWarnings("unchecked") // create returned a non-error result, so this is safe
+                    V result = (V) resultOrError;
+                    return result;
+                });
+    }
 }

src/main/java/com/google/inject/internal/Indexer.java

@@ -1,4 +1,4 @@
-package com.google.inject.multibindings;
+package com.google.inject.internal;
 
 import com.google.common.base.Objects;
 import com.google.inject.Binding;
@@ -23,17 +23,22 @@ import java.lang.annotation.Annotation;
 /**
  * Visits bindings to return a {@code IndexedBinding} that can be used to emulate the binding
  * deduplication that Guice internally performs.
+ *
+ * <p>Note: simply using equals/hashCode on the BindingImpls doesn't work because they all have
+ * unique annotations. This works around that by reimplementing equality semantics that ignores
+ * {@link Element#uniqueId()}. A better solution might be to introduce the idea of an 'anonymous'
+ * binding to guice, that might support this usecase directly.
  */
-class Indexer extends DefaultBindingTargetVisitor<Object, Indexer.IndexedBinding>
+public class Indexer extends DefaultBindingTargetVisitor<Object, Indexer.IndexedBinding>
         implements BindingScopingVisitor<Object> {
     private static final Object EAGER_SINGLETON = new Object();
-    final Injector injector;
+    private final Injector injector;
 
-    Indexer(Injector injector) {
+    public Indexer(Injector injector) {
         this.injector = injector;
     }
 
-    boolean isIndexable(Binding<?> binding) {
+    public boolean isIndexable(Binding<?> binding) {
         return binding.getKey().getAnnotation() instanceof Element;
     }
 
@@ -126,7 +131,7 @@ class Indexer extends DefaultBindingTargetVisitor<Object, Indexer.IndexedBinding
         PROVIDED_BY,
     }
 
-    static class IndexedBinding {
+    public static class IndexedBinding {
         final String annotationName;
         final Element.Type annotationType;
         final TypeLiteral<?> typeLiteral;
@@ -134,7 +139,7 @@ class Indexer extends DefaultBindingTargetVisitor<Object, Indexer.IndexedBinding
         final BindingType type;
         final Object extraEquality;
 
-        IndexedBinding(Binding<?> binding, BindingType type, Object scope, Object extraEquality) {
+        public IndexedBinding(Binding<?> binding, BindingType type, Object scope, Object extraEquality) {
             this.scope = scope;
             this.type = type;
             this.extraEquality = extraEquality;

src/main/java/com/google/inject/internal/InheritingState.java

@@ -3,17 +3,23 @@ package com.google.inject.internal;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
 import com.google.inject.Binding;
 import com.google.inject.Key;
 import com.google.inject.Scope;
 import com.google.inject.TypeLiteral;
+import com.google.inject.spi.InjectionRequest;
+import com.google.inject.spi.MembersInjectorLookup;
 import com.google.inject.spi.ModuleAnnotatedMethodScannerBinding;
+import com.google.inject.spi.ProviderLookup;
 import com.google.inject.spi.ProvisionListenerBinding;
 import com.google.inject.spi.ScopeBinding;
+import com.google.inject.spi.StaticInjectionRequest;
 import com.google.inject.spi.TypeConverterBinding;
 import com.google.inject.spi.TypeListenerBinding;
 
 import java.lang.annotation.Annotation;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
@@ -27,9 +33,13 @@ final class InheritingState implements State {
 
     // Must be a linked hashmap in order to preserve order of bindings in Modules.
     private final Map<Key<?>, Binding<?>> explicitBindingsMutable = Maps.newLinkedHashMap();
-    private final Map<Key<?>, Binding<?>> explicitBindings
+    private final Map<Key<?>, Binding<?>> explicitBindings =
-            = Collections.unmodifiableMap(explicitBindingsMutable);
+            Collections.unmodifiableMap(explicitBindingsMutable);
     private final Map<Class<? extends Annotation>, ScopeBinding> scopes = Maps.newHashMap();
+    private final Set<ProviderLookup<?>> providerLookups = Sets.newLinkedHashSet();
+    private final Set<StaticInjectionRequest> staticInjectionRequests = Sets.newLinkedHashSet();
+    private final Set<MembersInjectorLookup<?>> membersInjectorLookups = Sets.newLinkedHashSet();
+    private final Set<InjectionRequest<?>> injectionRequests = Sets.newLinkedHashSet();
     private final List<TypeConverterBinding> converters = Lists.newArrayList();
     private final List<TypeListenerBinding> typeListenerBindings = Lists.newArrayList();
     private final List<ProvisionListenerBinding> provisionListenerBindings = Lists.newArrayList();
@@ -43,41 +53,95 @@ final class InheritingState implements State {
         this.blacklistedKeys = new WeakKeySet(lock);
     }
 
+    @Override
     public State parent() {
         return parent;
     }
 
     @SuppressWarnings("unchecked") // we only put in BindingImpls that match their key types
+    @Override
     public <T> BindingImpl<T> getExplicitBinding(Key<T> key) {
         Binding<?> binding = explicitBindings.get(key);
         return binding != null ? (BindingImpl<T>) binding : parent.getExplicitBinding(key);
     }
 
+    @Override
     public Map<Key<?>, Binding<?>> getExplicitBindingsThisLevel() {
         return explicitBindings;
     }
 
+    @Override
     public void putBinding(Key<?> key, BindingImpl<?> binding) {
         explicitBindingsMutable.put(key, binding);
     }
 
+    @Override
+    public void putProviderLookup(ProviderLookup<?> lookup) {
+        providerLookups.add(lookup);
+    }
+
+    @Override
+    public Set<ProviderLookup<?>> getProviderLookupsThisLevel() {
+        return providerLookups;
+    }
+
+    @Override
+    public void putStaticInjectionRequest(StaticInjectionRequest staticInjectionRequest) {
+        staticInjectionRequests.add(staticInjectionRequest);
+    }
+
+    @Override
+    public Set<StaticInjectionRequest> getStaticInjectionRequestsThisLevel() {
+        return staticInjectionRequests;
+    }
+
+    @Override
+    public void putInjectionRequest(InjectionRequest<?> injectionRequest) {
+        injectionRequests.add(injectionRequest);
+    }
+
+    @Override
+    public Set<InjectionRequest<?>> getInjectionRequestsThisLevel() {
+        return injectionRequests;
+    }
+
+    @Override
+    public void putMembersInjectorLookup(MembersInjectorLookup<?> membersInjectorLookup) {
+        membersInjectorLookups.add(membersInjectorLookup);
+    }
+
+    @Override
+    public Set<MembersInjectorLookup<?>> getMembersInjectorLookupsThisLevel() {
+        return membersInjectorLookups;
+    }
+
+    @Override
     public ScopeBinding getScopeBinding(Class<? extends Annotation> annotationType) {
         ScopeBinding scopeBinding = scopes.get(annotationType);
         return scopeBinding != null ? scopeBinding : parent.getScopeBinding(annotationType);
     }
 
+    @Override
     public void putScopeBinding(Class<? extends Annotation> annotationType, ScopeBinding scope) {
         scopes.put(annotationType, scope);
     }
 
+    @Override
+    public Collection<ScopeBinding> getScopeBindingsThisLevel() {
+        return scopes.values();
+    }
+
+    @Override
     public Iterable<TypeConverterBinding> getConvertersThisLevel() {
         return converters;
     }
 
+    @Override
     public void addConverter(TypeConverterBinding typeConverterBinding) {
         converters.add(typeConverterBinding);
     }
 
+    @Override
     public TypeConverterBinding getConverter(
             String stringValue, TypeLiteral<?> type, Errors errors, Object source) {
         TypeConverterBinding matchingConverter = null;
@@ -94,10 +158,12 @@ final class InheritingState implements State {
         return matchingConverter;
     }
 
+    @Override
     public void addTypeListener(TypeListenerBinding listenerBinding) {
         typeListenerBindings.add(listenerBinding);
     }
 
+    @Override
     public List<TypeListenerBinding> getTypeListenerBindings() {
         List<TypeListenerBinding> parentBindings = parent.getTypeListenerBindings();
         List<TypeListenerBinding> result =
@@ -107,10 +173,17 @@ final class InheritingState implements State {
         return result;
     }
 
+    @Override
+    public List<TypeListenerBinding> getTypeListenerBindingsThisLevel() {
+        return typeListenerBindings;
+    }
+
+    @Override
     public void addProvisionListener(ProvisionListenerBinding listenerBinding) {
         provisionListenerBindings.add(listenerBinding);
     }
 
+    @Override
     public List<ProvisionListenerBinding> getProvisionListenerBindings() {
         List<ProvisionListenerBinding> parentBindings = parent.getProvisionListenerBindings();
         List<ProvisionListenerBinding> result =
@@ -120,10 +193,17 @@ final class InheritingState implements State {
         return result;
     }
 
+    @Override
+    public List<ProvisionListenerBinding> getProvisionListenerBindingsThisLevel() {
+        return provisionListenerBindings;
+    }
+
+    @Override
     public void addScanner(ModuleAnnotatedMethodScannerBinding scanner) {
         scannerBindings.add(scanner);
     }
 
+    @Override
     public List<ModuleAnnotatedMethodScannerBinding> getScannerBindings() {
         List<ModuleAnnotatedMethodScannerBinding> parentBindings = parent.getScannerBindings();
         List<ModuleAnnotatedMethodScannerBinding> result =
@@ -133,23 +213,33 @@ final class InheritingState implements State {
         return result;
     }
 
+    @Override
+    public List<ModuleAnnotatedMethodScannerBinding> getScannerBindingsThisLevel() {
+        return scannerBindings;
+    }
+
+    @Override
     public void blacklist(Key<?> key, State state, Object source) {
         parent.blacklist(key, state, source);
         blacklistedKeys.add(key, state, source);
     }
 
+    @Override
     public boolean isBlacklisted(Key<?> key) {
         return blacklistedKeys.contains(key);
     }
 
+    @Override
     public Set<Object> getSourcesForBlacklistedKey(Key<?> key) {
         return blacklistedKeys.getSources(key);
     }
 
+    @Override
     public Object lock() {
         return lock;
     }
 
+    @Override
     public Map<Class<? extends Annotation>, Scope> getScopes() {
         ImmutableMap.Builder<Class<? extends Annotation>, Scope> builder = ImmutableMap.builder();
         for (Map.Entry<Class<? extends Annotation>, ScopeBinding> entry : scopes.entrySet()) {

src/main/java/com/google/inject/internal/Initializable.java

@@ -8,5 +8,5 @@ interface Initializable<T> {
     /**
      * Ensures the reference is initialized, then returns it.
      */
-    T get(Errors errors) throws ErrorsException;
+    T get() throws InternalProvisionException;
 }

src/main/java/com/google/inject/internal/Initializables.java

@@ -6,8 +6,8 @@ final class Initializables {
      * Returns an initializable for an instance that requires no initialization.
      */
     static <T> Initializable<T> of(final T instance) {
-        return new Initializable<T>() {
+        return new Initializable<>() {
-            public T get(Errors errors) throws ErrorsException {
+            public T get() {
                 return instance;
             }
 

src/main/java/com/google/inject/internal/Initializer.java

@@ -3,15 +3,16 @@ package com.google.inject.internal;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
+import com.google.common.collect.Multimap;
 import com.google.inject.Binding;
 import com.google.inject.Key;
 import com.google.inject.Stage;
 import com.google.inject.TypeLiteral;
 import com.google.inject.spi.InjectionPoint;
 
-import java.util.Map;
+import java.util.IdentityHashMap;
+import java.util.List;
 import java.util.Set;
-import java.util.concurrent.CountDownLatch;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
@@ -23,27 +24,30 @@ import static com.google.common.base.Preconditions.checkNotNull;
  */
 final class Initializer {
 
-    /**
+    /** Is set to true once {@link #validateOustandingInjections} is called. */
-     * the only thread that we'll use to inject members.
+    private volatile boolean validationStarted = false;
-     */
-    private final Thread creatingThread = Thread.currentThread();
 
     /**
-     * zero means everything is injected.
+     * Allows us to detect circular dependencies. It's only used during injectable reference
+     * initialization. After initialization direct access through volatile field is used.
      */
-    private final CountDownLatch ready = new CountDownLatch(1);
+    private final CycleDetectingLock.CycleDetectingLockFactory<Class<?>> cycleDetectingLockFactory =
+            new CycleDetectingLock.CycleDetectingLockFactory<>();
 
     /**
-     * Maps from instances that need injection to the MembersInjector that will inject them.
+     * Instances that need injection during injector creation to a source that registered them. New
+     * references added before {@link #validateOustandingInjections}. Cleared up in {@link
+     * #injectAll}.
      */
-    private final Map<Object, MembersInjectorImpl<?>> pendingMembersInjectors =
+    private final List<InjectableReference<?>> pendingInjections = Lists.newArrayList();
+
+    /**
+     * Map that guarantees that no instance would get two references. New references added before
+     * {@link #validateOustandingInjections}. Cleared up in {@link #validateOustandingInjections}.
+     */
+    private final IdentityHashMap<Object, InjectableReference<?>> initializablesCache =
             Maps.newIdentityHashMap();
 
-    /**
-     * Maps instances that need injection to a source that registered them
-     */
-    private final Map<Object, InjectableReference<?>> pendingInjection = Maps.newIdentityHashMap();
-
     /**
      * Registers an instance for member injection when that step is performed.
      *
@@ -55,21 +59,35 @@ final class Initializer {
     <T> Initializable<T> requestInjection(InjectorImpl injector, T instance, Binding<T> binding,
                                           Object source, Set<InjectionPoint> injectionPoints) {
         checkNotNull(source);
-
+        Preconditions.checkState(
+                !validationStarted, "Member injection could not be requested after validation is started");
         ProvisionListenerStackCallback<T> provisionCallback =
                 binding == null ? null : injector.provisionListenerStore.get(binding);
 
         // short circuit if the object has no injections or listeners.
         if (instance == null || (injectionPoints.isEmpty()
                 && !injector.membersInjectorStore.hasTypeListeners()
-                && (provisionCallback == null || !provisionCallback.hasListeners()))) {
+                && (provisionCallback == null))) {
             return Initializables.of(instance);
         }
 
-        InjectableReference<T> initializable = new InjectableReference<T>(
+        if (initializablesCache.containsKey(instance)) {
-                injector, instance, binding == null ? null : binding.getKey(), provisionCallback, source);
+            @SuppressWarnings("unchecked") // Map from T to InjectableReference<T>
-        pendingInjection.put(instance, initializable);
+                    Initializable<T> cached = (Initializable<T>) initializablesCache.get(instance);
-        return initializable;
+            return cached;
+        }
+
+        InjectableReference<T> injectableReference =
+                new InjectableReference<T>(
+                        injector,
+                        instance,
+                        binding == null ? null : binding.getKey(),
+                        provisionCallback,
+                        source,
+                        cycleDetectingLockFactory.create(instance.getClass()));
+        initializablesCache.put(instance, injectableReference);
+        pendingInjections.add(injectableReference);
+        return injectableReference;
     }
 
     /**
@@ -77,9 +95,11 @@ final class Initializer {
      * on the injected instances.
      */
     void validateOustandingInjections(Errors errors) {
-        for (InjectableReference<?> reference : pendingInjection.values()) {
+        validationStarted = true;
+        initializablesCache.clear();
+        for (InjectableReference<?> reference : pendingInjections) {
             try {
-                pendingMembersInjectors.put(reference.instance, reference.validate(errors));
+                reference.validate(errors);
             } catch (ErrorsException e) {
                 errors.merge(e.getErrors());
             }
@@ -92,85 +112,122 @@ final class Initializer {
      * instances are codependent (directly or transitively), ordering of injection is arbitrary.
      */
     void injectAll(final Errors errors) {
-        // loop over a defensive copy since ensureInjected() mutates the set. Unfortunately, that copy
+        Preconditions.checkState(validationStarted, "Validation should be done before injection");
-        // is made complicated by a bug in IBM's JDK, wherein entrySet().toArray(Object[]) doesn't work
+        for (InjectableReference<?> reference : pendingInjections) {
-        for (InjectableReference<?> reference : Lists.newArrayList(pendingInjection.values())) {
             try {
-                reference.get(errors);
+                reference.get();
-            } catch (ErrorsException e) {
+            } catch (InternalProvisionException ipe) {
-                errors.merge(e.getErrors());
+                errors.merge(ipe);
             }
         }
+        pendingInjections.clear();
+    }
 
-        if (!pendingInjection.isEmpty()) {
+    private enum InjectableReferenceState {
-            throw new AssertionError("Failed to satisfy " + pendingInjection);
+        NEW,
+        VALIDATED,
+        INJECTING,
+        READY
     }
 
-        ready.countDown();
+    private static class InjectableReference<T> implements Initializable<T> {
-    }
+        private volatile InjectableReferenceState state = InjectableReferenceState.NEW;
+        private volatile MembersInjectorImpl<T> membersInjector = null;
 
-    private class InjectableReference<T> implements Initializable<T> {
         private final InjectorImpl injector;
         private final T instance;
         private final Object source;
         private final Key<T> key;
         private final ProvisionListenerStackCallback<T> provisionCallback;
+        private final CycleDetectingLock<?> lock;
 
         public InjectableReference(InjectorImpl injector, T instance, Key<T> key,
-                                   ProvisionListenerStackCallback<T> provisionCallback, Object source) {
+                                   ProvisionListenerStackCallback<T> provisionCallback,
+                                   Object source,
+                                   CycleDetectingLock<?> lock) {
             this.injector = injector;
             this.key = key; // possibly null!
             this.provisionCallback = provisionCallback; // possibly null!
             this.instance = checkNotNull(instance, "instance");
             this.source = checkNotNull(source, "source");
+            this.lock = checkNotNull(lock, "lock");
         }
 
-        public MembersInjectorImpl<T> validate(Errors errors) throws ErrorsException {
+        public void validate(Errors errors) throws ErrorsException {
             @SuppressWarnings("unchecked") // the type of 'T' is a TypeLiteral<T>
             TypeLiteral<T> type = TypeLiteral.get((Class<T>) instance.getClass());
-            return injector.membersInjectorStore.get(type, errors.withSource(source));
+            membersInjector = injector.membersInjectorStore.get(type, errors.withSource(source));
+            Preconditions.checkNotNull(
+                    membersInjector,
+                    "No membersInjector available for instance: %s, from key: %s",
+                    instance,
+                    key);
+            state = InjectableReferenceState.VALIDATED;
         }
 
         /**
          * Reentrant. If {@code instance} was registered for injection at injector-creation time, this
          * method will ensure that all its members have been injected before returning.
          */
-        public T get(Errors errors) throws ErrorsException {
+        @Override
-            if (ready.getCount() == 0) {
+        public T get() throws InternalProvisionException {
+            // skipping acquiring lock if initialization is already finished
+            if (state == InjectableReferenceState.READY) {
                 return instance;
             }
+            // acquire lock for current binding to initialize an instance
+            Multimap<?, ?> lockCycle = lock.lockOrDetectPotentialLocksCycle();
+            if (!lockCycle.isEmpty()) {
+                // Potential deadlock detected and creation lock is not taken.
+                // According to injectAll()'s contract return non-initialized instance.
 
-            // just wait for everything to be injected by another thread
+                // This condition should not be possible under the current Guice implementation.
-            if (Thread.currentThread() != creatingThread) {
+                // This clause exists for defensive programming purposes.
+
+                // Reasoning:
+                // get() is called either directly from injectAll(), holds no locks and can not create
+                // a cycle, or it is called through a singleton scope, which resolves deadlocks by itself.
+                // Before calling get() object has to be requested for injection.
+                // Initializer.requestInjection() is called either for constant object bindings, which wrap
+                // creation into a Singleton scope, or from Binder.requestInjection(), which
+                // has to use Singleton scope to reuse the same InjectableReference to potentially
+                // create a lock cycle.
+                return instance;
+            }
             try {
-                    ready.await();
+                // lock acquired, current thread owns this instance initialization
+                switch (state) {
+                    case READY:
                         return instance;
-                } catch (InterruptedException e) {
+                    // When instance depends on itself in the same thread potential dead lock
-                    // Give up, since we don't know if our injection is ready
+                    // is not detected. We have to prevent a stack overflow and we use
-                    throw new RuntimeException(e);
+                    // an "injecting" stage to short-circuit a call.
+                    case INJECTING:
+                        return instance;
+                    case VALIDATED:
+                        state = InjectableReferenceState.INJECTING;
+                        break;
+                    case NEW:
+                        throw new IllegalStateException("InjectableReference is not validated yet");
+                    default:
+                        throw new IllegalStateException("Unknown state: " + state);
                 }
-            }
-
-            // toInject needs injection, do it right away. we only do this once, even if it fails
-            if (pendingInjection.remove(instance) != null) {
-                // safe because we only insert a members injector for the appropriate instance
-                @SuppressWarnings("unchecked")
-                MembersInjectorImpl<T> membersInjector =
-                        (MembersInjectorImpl<T>) pendingMembersInjectors.remove(instance);
-                Preconditions.checkState(membersInjector != null,
-                        "No membersInjector available for instance: %s, from key: %s", instance, key);
 
                 // if in Stage.TOOL, we only want to inject & notify toolable injection points.
                 // (otherwise we'll inject all of them)
-                membersInjector.injectAndNotify(instance,
+                try {
-                        errors.withSource(source),
+                    membersInjector.injectAndNotify(
-                        key,
+                            instance, key, provisionCallback, source, injector.options.stage == Stage.TOOL);
-                        provisionCallback,
+                } catch (InternalProvisionException ipe) {
-                        source,
+                    throw ipe.addSource(source);
-                        injector.options.stage == Stage.TOOL);
                 }
-
+                // mark instance as ready to skip a lock on subsequent calls
+                state = InjectableReferenceState.READY;
                 return instance;
+            } finally {
+                // always release our creation lock, even on failures
+                lock.unlock();
+            }
         }
 
         @Override

src/main/java/com/google/inject/internal/InjectionRequestProcessor.java

@@ -98,21 +98,19 @@ final class InjectionRequestProcessor extends AbstractProcessor {
         }
 
         void injectMembers() {
-            try {
+            try (InternalContext context = injector.enterContext()) {
-                injector.callInContext(new ContextualCallable<Void>() {
+                boolean isStageTool = injector.options.stage == Stage.TOOL;
-                    public Void call(InternalContext context) {
                 for (SingleMemberInjector memberInjector : memberInjectors) {
                     // Run injections if we're not in tool stage (ie, PRODUCTION or DEV),
                     // or if we are in tool stage and the injection point is toolable.
-                            if (injector.options.stage != Stage.TOOL || memberInjector.getInjectionPoint().isToolable()) {
+                    if (!isStageTool || memberInjector.getInjectionPoint().isToolable()) {
-                                memberInjector.inject(errors, context, null);
+                        try {
-                            }
+                            memberInjector.inject(context, null);
-                        }
+                        } catch (InternalProvisionException e) {
-                        return null;
+                            errors.merge(e);
-                    }
+                        }
-                });
+                    }
-            } catch (ErrorsException e) {
+                }
-                throw new AssertionError();
             }
         }
     }

src/main/java/com/google/inject/internal/InjectorImpl.java

@@ -1,12 +1,16 @@
 package com.google.inject.internal;
 
+import static com.google.common.base.Preconditions.checkNotNull;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Objects;
+import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Lists;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Maps;
+import com.google.common.collect.Multimaps;
 import com.google.common.collect.Sets;
 import com.google.inject.Binder;
 import com.google.inject.Binding;
@@ -18,7 +22,6 @@ import com.google.inject.MembersInjector;
 import com.google.inject.Module;
 import com.google.inject.ProvidedBy;
 import com.google.inject.Provider;
-import com.google.inject.ProvisionException;
 import com.google.inject.Scope;
 import com.google.inject.Stage;
 import com.google.inject.TypeLiteral;
@@ -26,8 +29,10 @@ import com.google.inject.internal.util.SourceProvider;
 import com.google.inject.spi.BindingTargetVisitor;
 import com.google.inject.spi.ConvertedConstantBinding;
 import com.google.inject.spi.Dependency;
+import com.google.inject.spi.Element;
 import com.google.inject.spi.HasDependencies;
 import com.google.inject.spi.InjectionPoint;
+import com.google.inject.spi.InstanceBinding;
 import com.google.inject.spi.ProviderBinding;
 import com.google.inject.spi.TypeConverterBinding;
 import com.google.inject.util.Providers;
@@ -42,45 +47,46 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.ConcurrentMap;
 
 /**
  * Default {@link Injector} implementation.
  *
  */
 final class InjectorImpl implements Injector, Lookups {
+
     public static final TypeLiteral<String> STRING_TYPE = TypeLiteral.get(String.class);
-    /**
+
-     * Synchronization: map value is modified only for the current thread,
-     * it's ok to read map values of other threads. It can change between your
-     * calls.
-     *
-     * @see #getGlobalInternalContext
-     */
-    private static final ConcurrentMap<Thread, InternalContext> globalInternalContext =
-            Maps.newConcurrentMap();
     final State state;
+
     final InjectorImpl parent;
-    final BindingsMultimap bindingsMultimap = new BindingsMultimap();
+
+    final ListMultimap<TypeLiteral<?>, Binding<?>> bindingsMultimap = ArrayListMultimap.create();
+
     final InjectorOptions options;
+
     /**
      * Just-in-time binding cache. Guarded by state.lock()
      */
     final Map<Key<?>, BindingImpl<?>> jitBindings = Maps.newHashMap();
+
     /**
      * Cache of Keys that we were unable to create JIT bindings for, so we don't
      * keep trying.  Also guarded by state.lock().
      */
     final Set<Key<?>> failedJitBindings = Sets.newHashSet();
+
+    Lookups lookups = new DeferredLookups(this);
+
+    /** The set of types passed to {@link #getMembersInjector} and {@link #injectMembers}. */
+    final Set<TypeLiteral<?>> userRequestedMembersInjectorTypes = Sets.newConcurrentHashSet();
+
     /**
      * Cached constructor injectors for each type
      */
     final ConstructorInjectorStore constructors = new ConstructorInjectorStore(this);
-    /**
+
-     * @see #getGlobalInternalContext
-     */
     private final ThreadLocal<Object[]> localContext;
-    Lookups lookups = new DeferredLookups(this);
+
     /**
      * Cached field and method injectors for each type.
      */
@@ -98,56 +104,32 @@ final class InjectorImpl implements Injector, Lookups {
         if (parent != null) {
             localContext = parent.localContext;
         } else {
-            localContext = new ThreadLocal<Object[]>();
+            // No ThreadLocal.initialValue(), as that would cause classloader leaks. See
+            // https://github.com/google/guice/issues/288#issuecomment-48216933,
+            // https://github.com/google/guice/issues/288#issuecomment-48216944
+            localContext = new ThreadLocal<>();
         }
     }
 
-    /**
+
-     * Returns true if the key type is Provider (but not a subclass of Provider).
+    /** Only to be called by the {@link SingletonScope} provider. */
-     */
+    InternalContext getLocalContext() {
-    private static boolean isProvider(Key<?> key) {
+        return (InternalContext) localContext.get()[0];
-        return key.getTypeLiteral().getRawType().equals(Provider.class);
     }
 
-    private static boolean isTypeLiteral(Key<?> key) {
+    InternalContext enterContext() {
-        return key.getTypeLiteral().getRawType().equals(TypeLiteral.class);
+        Object[] reference = localContext.get();
+        if (reference == null) {
+            reference = new Object[1];
+            localContext.set(reference);
         }
-
+        InternalContext ctx = (InternalContext) reference[0];
-    private static <T> Key<T> getProvidedKey(Key<Provider<T>> key, Errors errors) throws ErrorsException {
+        if (ctx == null) {
-        Type providerType = key.getTypeLiteral().getType();
+            reference[0] = ctx = new InternalContext(options, reference);
-
+        } else {
-        // If the Provider has no type parameter (raw Provider)...
+            ctx.enter();
-        if (!(providerType instanceof ParameterizedType)) {
-            throw errors.cannotInjectRawProvider().toException();
         }
-
+        return ctx;
-        Type entryType = ((ParameterizedType) providerType).getActualTypeArguments()[0];
-
-        @SuppressWarnings("unchecked") // safe because T came from Key<Provider<T>>
-                Key<T> providedKey = (Key<T>) key.ofType(entryType);
-        return providedKey;
-    }
-
-    /**
-     * Returns true if the key type is MembersInjector (but not a subclass of MembersInjector).
-     */
-    private static boolean isMembersInjector(Key<?> key) {
-        return key.getTypeLiteral().getRawType().equals(MembersInjector.class)
-                && key.getAnnotationType() == null;
-    }
-
-    /**
-     * Provides access to the internal context for the current injector of all threads.
-     * One does not need to use this from Guice source code as context could be passed on the stack.
-     * It is required for custom scopes which are called from Guice and sometimes do require
-     * access to current internal context, but it is not passed in. Contrary to {@link #localContext}
-     * it is not used to store injector-specific state, but to provide easy access to the current
-     * state.
-     *
-     * @return unmodifiable map
-     */
-    static Map<Thread, InternalContext> getGlobalInternalContext() {
-        return Collections.unmodifiableMap(globalInternalContext);
     }
 
     /**
@@ -155,23 +137,23 @@ final class InjectorImpl implements Injector, Lookups {
      */
     void index() {
         for (Binding<?> binding : state.getExplicitBindingsThisLevel().values()) {
-            index(binding);
-        }
-    }
-
-    <T> void index(Binding<T> binding) {
             bindingsMultimap.put(binding.getKey().getTypeLiteral(), binding);
         }
+    }
 
+    @Override
     public <T> List<Binding<T>> findBindingsByType(TypeLiteral<T> type) {
-        return bindingsMultimap.getAll(type);
+        @SuppressWarnings("unchecked") // safe because we only put matching entries into the map
+        List<Binding<T>> list = (List<Binding<T>>) (List) bindingsMultimap.get(checkNotNull(type, "type"));
+        return Collections.unmodifiableList(list);
     }
 
     /**
      * Returns the binding for {@code key}
      */
+    @Override
     public <T> BindingImpl<T> getBinding(Key<T> key) {
-        Errors errors = new Errors(key);
+        Errors errors = new Errors(checkNotNull(key, "key"));
         try {
             BindingImpl<T> result = getBindingOrThrow(key, errors, JitLimitation.EXISTING_JIT);
             errors.throwConfigurationExceptionIfErrorsExist();
@@ -181,6 +163,7 @@ final class InjectorImpl implements Injector, Lookups {
         }
     }
 
+    @Override
     public <T> BindingImpl<T> getExistingBinding(Key<T> key) {
         // Check explicit bindings, i.e. bindings created by modules.
         BindingImpl<T> explicitBinding = state.getExplicitBinding(key);
@@ -235,21 +218,22 @@ final class InjectorImpl implements Injector, Lookups {
         return getJustInTimeBinding(key, errors, jitType);
     }
 
+    @Override
     public <T> Binding<T> getBinding(Class<T> type) {
-        return getBinding(Key.get(type));
+        return getBinding(Key.get(checkNotNull(type, "type")));
     }
 
+    @Override
     public Injector getParent() {
         return parent;
     }
 
+    @Override
     public Injector createChildInjector(Iterable<? extends Module> modules) {
-        return new InternalInjectorCreator()
+        return new InternalInjectorCreator().parentInjector(this).addModules(modules).build();
-                .parentInjector(this)
-                .addModules(modules)
-                .build();
     }
 
+    @Override
     public Injector createChildInjector(Module... modules) {
         return createChildInjector(ImmutableList.copyOf(modules));
     }
@@ -304,6 +288,40 @@ final class InjectorImpl implements Injector, Lookups {
         } // end synchronized(state.lock())
     }
 
+    /**
+     * Returns true if the key type is Provider (but not a subclass of Provider).
+     */
+    private static boolean isProvider(Key<?> key) {
+        return key.getTypeLiteral().getRawType().equals(Provider.class);
+    }
+
+    private static boolean isTypeLiteral(Key<?> key) {
+        return key.getTypeLiteral().getRawType().equals(TypeLiteral.class);
+    }
+
+
+    private static <T> Key<T> getProvidedKey(Key<Provider<T>> key, Errors errors)
+            throws ErrorsException {
+        Type providerType = key.getTypeLiteral().getType();
+
+        // If the Provider has no type parameter (raw Provider)...
+        if (!(providerType instanceof ParameterizedType)) {
+            throw errors.cannotInjectRawProvider().toException();
+        }
+
+        Type entryType = ((ParameterizedType) providerType).getActualTypeArguments()[0];
+
+        @SuppressWarnings("unchecked") // safe because T came from Key<Provider<T>>
+                Key<T> providedKey = (Key<T>) key.ofType(entryType);
+        return providedKey;
+    }
+
+    /** Returns true if the key type is MembersInjector (but not a subclass of MembersInjector). */
+    private static boolean isMembersInjector(Key<?> key) {
+        return key.getTypeLiteral().getRawType().equals(MembersInjector.class)
+                && key.getAnnotationType() == null;
+    }
+
     private <T> BindingImpl<MembersInjector<T>> createMembersInjectorBinding(
             Key<MembersInjector<T>> key, Errors errors) throws ErrorsException {
         Type membersInjectorType = key.getTypeLiteral().getType();
@@ -316,12 +334,11 @@ final class InjectorImpl implements Injector, Lookups {
                 ((ParameterizedType) membersInjectorType).getActualTypeArguments()[0]);
         MembersInjector<T> membersInjector = membersInjectorStore.get(instanceType, errors);
 
-        InternalFactory<MembersInjector<T>> factory = new ConstantFactory<MembersInjector<T>>(
+        InternalFactory<MembersInjector<T>> factory =
-                Initializables.of(membersInjector));
+                new ConstantFactory<>(Initializables.of(membersInjector));
 
-
+        return new InstanceBindingImpl<>(this, key, SourceProvider.UNKNOWN_SOURCE,
-        return new InstanceBindingImpl<MembersInjector<T>>(this, key, SourceProvider.UNKNOWN_SOURCE,
+                factory, ImmutableSet.of(), membersInjector);
-                factory, ImmutableSet.<InjectionPoint>of(), membersInjector);
     }
 
     /**
@@ -350,7 +367,11 @@ final class InjectorImpl implements Injector, Lookups {
             return null;
         }
 
-        String stringValue = stringBinding.getProvider().get();
+        // We can't call getProvider().get() because this InstanceBinding may not have been inintialized
+        // yet (because we may have been called during InternalInjectorCreator.initializeStatically and
+        // instance binding validation hasn't happened yet.)
+        @SuppressWarnings("unchecked")
+        String stringValue = ((InstanceBinding<String>) stringBinding).getInstance();
         Object source = stringBinding.getSource();
 
         // Find a matching type converter.
@@ -379,8 +400,6 @@ final class InjectorImpl implements Injector, Lookups {
 
             return new ConvertedConstantBindingImpl<T>(this, key, converted, stringBinding,
                     typeConverterBinding);
-        } catch (ErrorsException e) {
-            throw e;
         } catch (RuntimeException e) {
             throw errors.conversionError(stringValue, source, type, typeConverterBinding, e)
                     .toException();
@@ -411,7 +430,7 @@ final class InjectorImpl implements Injector, Lookups {
                     // so that cached exceptions while constructing it get stored.
                     // See TypeListenerTest#testTypeListenerThrows
                     removeFailedJitBinding(binding, null);
-                    cleanup(binding, new HashSet<Key>());
+                    cleanup(binding, new HashSet<>());
                 }
             }
         }
@@ -423,18 +442,18 @@ final class InjectorImpl implements Injector, Lookups {
      * optimistically added to allow circular dependency support, so dependencies may pass where they
      * should have failed.
      */
-    private boolean cleanup(BindingImpl<?> binding, Set<Key> encountered) {
+    private boolean cleanup(BindingImpl<?> binding, Set<Key<?>> encountered) {
         boolean bindingFailed = false;
         Set<Dependency<?>> deps = getInternalDependencies(binding);
-        for (Dependency dep : deps) {
+        for (Dependency<?> dep : deps) {
             Key<?> depKey = dep.getKey();
             InjectionPoint ip = dep.getInjectionPoint();
             if (encountered.add(depKey)) { // only check if we haven't looked at this key yet
-                BindingImpl depBinding = jitBindings.get(depKey);
+                BindingImpl<?> depBinding = jitBindings.get(depKey);
                 if (depBinding != null) { // if the binding still exists, validate
                     boolean failed = cleanup(depBinding, encountered); // if children fail, we fail
                     if (depBinding instanceof ConstructorBindingImpl) {
-                        ConstructorBindingImpl ctorBinding = (ConstructorBindingImpl) depBinding;
+                        ConstructorBindingImpl<?> ctorBinding = (ConstructorBindingImpl) depBinding;
                         ip = ctorBinding.getInternalConstructor();
                         if (!ctorBinding.isInitialized()) {
                             failed = true;
@@ -493,7 +512,7 @@ final class InjectorImpl implements Injector, Lookups {
 
         // Don't try to inject arrays or enums annotated with @ImplementedBy.
         if (rawType.isArray() || (rawType.isEnum() && implementedBy != null)) {
-            throw errors.missingImplementation(key).toException();
+            throw errors.missingImplementationWithHint(key, this).toException();
         }
 
         // Handle TypeLiteral<T> by binding the inner type
@@ -552,10 +571,9 @@ final class InjectorImpl implements Injector, Lookups {
 
         @SuppressWarnings("unchecked") // by definition, innerType == T, so this is safe
         TypeLiteral<T> value = (TypeLiteral<T>) TypeLiteral.get(innerType);
-        InternalFactory<TypeLiteral<T>> factory = new ConstantFactory<TypeLiteral<T>>(
+        InternalFactory<TypeLiteral<T>> factory = new ConstantFactory<>(Initializables.of(value));
-                Initializables.of(value));
+        return new InstanceBindingImpl<>(this, key, SourceProvider.UNKNOWN_SOURCE,
-        return new InstanceBindingImpl<TypeLiteral<T>>(this, key, SourceProvider.UNKNOWN_SOURCE,
+                factory, ImmutableSet.of(), value);
-                factory, ImmutableSet.<InjectionPoint>of(), value);
     }
 
     /**
@@ -564,7 +582,7 @@ final class InjectorImpl implements Injector, Lookups {
     <T> BindingImpl<T> createProvidedByBinding(Key<T> key, Scoping scoping,
                                                ProvidedBy providedBy, Errors errors) throws ErrorsException {
         Class<?> rawType = key.getTypeLiteral().getRawType();
-        Class<? extends Provider<?>> providerType = providedBy.value();
+        Class<? extends javax.inject.Provider<?>> providerType = providedBy.value();
 
         // Make sure it's not the same type. TODO: Can we check for deeper loops?
         if (providerType == rawType) {
@@ -576,12 +594,11 @@ final class InjectorImpl implements Injector, Lookups {
         Key<? extends Provider<T>> providerKey = (Key<? extends Provider<T>>) Key.get(providerType);
         ProvidedByInternalFactory<T> internalFactory =
                 new ProvidedByInternalFactory<T>(rawType, providerType, providerKey);
-        Object source = rawType;
         BindingImpl<T> binding = LinkedProviderBindingImpl.createWithInitializer(
                 this,
                 key,
-                source,
+                rawType,
-                Scoping.<T>scope(key, this, internalFactory, source, scoping),
+                Scoping.<T>scope(key, this, internalFactory, rawType, scoping),
                 scoping,
                 providerKey,
                 internalFactory);
@@ -613,27 +630,14 @@ final class InjectorImpl implements Injector, Lookups {
 
         // Look up the target binding.
         final Key<? extends T> targetKey = Key.get(subclass);
-        final BindingImpl<? extends T> targetBinding = getBindingOrThrow(targetKey, errors, JitLimitation.NEW_OR_EXISTING_JIT);
 
-        InternalFactory<T> internalFactory = new InternalFactory<T>() {
+        FactoryProxy<T> factory = new FactoryProxy<>(this, key, targetKey, rawType);
-            public T get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked)
+        factory.notify(errors); // causes the factory to initialize itself internally
-                    throws ErrorsException {
-                context.pushState(targetKey, targetBinding.getSource());
-                try {
-                    return targetBinding.getInternalFactory().get(
-                            errors.withSource(targetKey), context, dependency, true);
-                } finally {
-                    context.popState();
-                }
-            }
-        };
-
-        Object source = rawType;
         return new LinkedBindingImpl<T>(
                 this,
                 key,
-                source,
+                rawType,
-                Scoping.<T>scope(key, this, internalFactory, source, scoping),
+                Scoping.<T>scope(key, this, factory, rawType, scoping),
                 scoping,
                 targetKey);
     }
@@ -725,9 +729,7 @@ final class InjectorImpl implements Injector, Lookups {
             return convertedBinding;
         }
 
-        if (!isTypeLiteral(key)
+        if (!isTypeLiteral(key) && jitDisabled && jitType != JitLimitation.NEW_OR_EXISTING_JIT) {
-                && jitDisabled
-                && jitType != JitLimitation.NEW_OR_EXISTING_JIT) {
             throw errors.jitDisabled(key).toException();
         }
 
@@ -757,10 +759,12 @@ final class InjectorImpl implements Injector, Lookups {
         return getBindingOrThrow(key, errors, jitType).getInternalFactory();
     }
 
+    @Override
     public Map<Key<?>, Binding<?>> getBindings() {
         return state.getExplicitBindingsThisLevel();
     }
 
+    @Override
     public Map<Key<?>, Binding<?>> getAllBindings() {
         synchronized (state.lock()) {
             return new ImmutableMap.Builder<Key<?>, Binding<?>>()
@@ -770,14 +774,47 @@ final class InjectorImpl implements Injector, Lookups {
         }
     }
 
+    @Override
     public Map<Class<? extends Annotation>, Scope> getScopeBindings() {
         return ImmutableMap.copyOf(state.getScopes());
     }
 
+    @Override
     public Set<TypeConverterBinding> getTypeConverterBindings() {
         return ImmutableSet.copyOf(state.getConvertersThisLevel());
     }
 
+    @Override
+    public List<Element> getElements() {
+        ImmutableList.Builder<Element> elements = ImmutableList.builder();
+        elements.addAll(getAllBindings().values());
+        elements.addAll(state.getProviderLookupsThisLevel());
+        elements.addAll(state.getConvertersThisLevel());
+        elements.addAll(state.getScopeBindingsThisLevel());
+        elements.addAll(state.getTypeListenerBindingsThisLevel());
+        elements.addAll(state.getProvisionListenerBindingsThisLevel());
+        elements.addAll(state.getScannerBindingsThisLevel());
+        elements.addAll(state.getStaticInjectionRequestsThisLevel());
+        elements.addAll(state.getMembersInjectorLookupsThisLevel());
+        elements.addAll(state.getInjectionRequestsThisLevel());
+
+        return elements.build();
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public Map<TypeLiteral<?>, List<InjectionPoint>> getAllMembersInjectorInjectionPoints() {
+        // Note, this is a safe cast per the ListMultimap javadocs.
+        // We could use Multimaps.asMap to avoid the cast, but unfortunately it's a @Beta method.
+        return (Map<TypeLiteral<?>, List<InjectionPoint>>)
+                (Map<TypeLiteral<?>, ?>)
+                        ImmutableListMultimap.copyOf(
+                                Multimaps.filterKeys(
+                                        membersInjectorStore.getAllInjectionPoints(),
+                                        userRequestedMembersInjectorTypes::contains))
+                                .asMap();
+    }
+
     /**
      * Returns parameter injectors, or {@code null} if there are no parameters.
      */
@@ -808,13 +845,18 @@ final class InjectorImpl implements Injector, Lookups {
         return new SingleParameterInjector<T>(dependency, binding);
     }
 
-    @SuppressWarnings("unchecked") // the members injector type is consistent with instance's type
+    @SuppressWarnings({"unchecked","rawtypes"}) // the members injector type is consistent with instance's type
+    @Override
     public void injectMembers(Object instance) {
         MembersInjector membersInjector = getMembersInjector(instance.getClass());
         membersInjector.injectMembers(instance);
     }
 
+    @Override
     public <T> MembersInjector<T> getMembersInjector(TypeLiteral<T> typeLiteral) {
+        checkNotNull(typeLiteral, "typeLiteral");
+        userRequestedMembersInjectorTypes.add(typeLiteral);
+
         Errors errors = new Errors(typeLiteral);
         try {
             return membersInjectorStore.get(typeLiteral, errors);
@@ -823,47 +865,45 @@ final class InjectorImpl implements Injector, Lookups {
         }
     }
 
+    @Override
     public <T> MembersInjector<T> getMembersInjector(Class<T> type) {
         return getMembersInjector(TypeLiteral.get(type));
     }
 
+    @Override
     public <T> Provider<T> getProvider(Class<T> type) {
-        return getProvider(Key.get(type));
+        return getProvider(Key.get(checkNotNull(type, "type")));
     }
 
     <T> Provider<T> getProviderOrThrow(final Dependency<T> dependency, Errors errors) throws ErrorsException {
         final Key<T> key = dependency.getKey();
         final BindingImpl<? extends T> binding = getBindingOrThrow(key, errors, JitLimitation.NO_JIT);
-
+        final InternalFactory<? extends T> internalFactory = binding.getInternalFactory();
-        return new Provider<T>() {
+        final Object source = binding.getSource();
+        return new Provider<>() {
             public T get() {
-                final Errors errors = new Errors(dependency);
+                InternalContext currentContext = enterContext();
+                Dependency<?> previous = currentContext.pushDependency(dependency, source);
                 try {
-                    T t = callInContext(new ContextualCallable<T>() {
+                    return internalFactory.get(currentContext, dependency, false);
-                        public T call(InternalContext context) throws ErrorsException {
+                } catch (InternalProvisionException e) {
-                            Dependency previous = context.pushDependency(dependency, binding.getSource());
+                    throw e.addSource(dependency).toProvisionException();
-                            try {
-                                return binding.getInternalFactory().get(errors, context, dependency, false);
                 } finally {
-                                context.popStateAndSetDependency(previous);
+                    currentContext.popStateAndSetDependency(previous);
-                            }
+                    currentContext.close();
-                        }
-                    });
-                    errors.throwIfNewErrors(0);
-                    return t;
-                } catch (ErrorsException e) {
-                    throw new ProvisionException(errors.merge(e.getErrors()).getMessages());
                 }
             }
 
             @Override
             public String toString() {
-                return binding.getInternalFactory().toString();
+                return internalFactory.toString();
             }
         };
     }
 
+    @Override
     public <T> Provider<T> getProvider(final Key<T> key) {
+        checkNotNull(key, "key");
         Errors errors = new Errors(key);
         try {
             Provider<T> result = getProviderOrThrow(Dependency.get(key), errors);
@@ -874,50 +914,16 @@ final class InjectorImpl implements Injector, Lookups {
         }
     }
 
+    @Override
     public <T> T getInstance(Key<T> key) {
         return getProvider(key).get();
     }
 
+    @Override
     public <T> T getInstance(Class<T> type) {
         return getProvider(type).get();
     }
 
-    /**
-     * Looks up thread local context. Creates (and removes) a new context if necessary.
-     */
-    <T> T callInContext(ContextualCallable<T> callable) throws ErrorsException {
-        Object[] reference = localContext.get();
-        if (reference == null) {
-            reference = new Object[1];
-            localContext.set(reference);
-        }
-        Thread currentThread = Thread.currentThread();
-        if (reference[0] == null) {
-            reference[0] = new InternalContext(options);
-            globalInternalContext.put(currentThread, (InternalContext) reference[0]);
-            try {
-                return callable.call((InternalContext) reference[0]);
-            } finally {
-                // Only clear contexts if this call created them.
-                reference[0] = null;
-                globalInternalContext.remove(currentThread);
-            }
-        } else {
-            Object previousGlobalInternalContext = globalInternalContext.get(currentThread);
-            globalInternalContext.put(currentThread, (InternalContext) reference[0]);
-            try {
-                // Someone else will clean up this local context.
-                return callable.call((InternalContext) reference[0]);
-            } finally {
-                if (previousGlobalInternalContext != null) {
-                    globalInternalContext.put(currentThread, (InternalContext) previousGlobalInternalContext);
-                } else {
-                    globalInternalContext.remove(currentThread);
-                }
-            }
-        }
-    }
-
     @Override
     public String toString() {
         return MoreObjects.toStringHelper(Injector.class)
@@ -994,21 +1000,20 @@ final class InjectorImpl implements Injector, Lookups {
 
         static <T> InternalFactory<Provider<T>> createInternalFactory(Binding<T> providedBinding) {
             final Provider<T> provider = providedBinding.getProvider();
-            return new InternalFactory<Provider<T>>() {
+            return (context, dependency, linked) -> provider;
-                public Provider<T> get(Errors errors, InternalContext context, Dependency dependency, boolean linked) {
-                    return provider;
-                }
-            };
         }
 
+        @Override
         public Key<? extends T> getProvidedKey() {
             return providedBinding.getKey();
         }
 
+        @Override
         public <V> V acceptTargetVisitor(BindingTargetVisitor<? super Provider<T>, V> visitor) {
             return visitor.visit(this);
         }
 
+        @Override
         public void applyTo(Binder binder) {
             throw new UnsupportedOperationException("This element represents a synthetic binding.");
         }
@@ -1021,6 +1026,7 @@ final class InjectorImpl implements Injector, Lookups {
                     .toString();
         }
 
+        @Override
         public Set<Dependency<?>> getDependencies() {
             return ImmutableSet.<Dependency<?>>of(Dependency.get(getProvidedKey()));
         }
@@ -1050,8 +1056,10 @@ final class InjectorImpl implements Injector, Lookups {
         final Binding<String> originalBinding;
         final TypeConverterBinding typeConverterBinding;
 
-        ConvertedConstantBindingImpl(
+        ConvertedConstantBindingImpl(InjectorImpl injector,
-                InjectorImpl injector, Key<T> key, T value, Binding<String> originalBinding,
+                                     Key<T> key,
+                                     T value,
+                                     Binding<String> originalBinding,
                                      TypeConverterBinding typeConverterBinding) {
             super(injector, key, originalBinding.getSource(),
                     new ConstantFactory<T>(Initializables.of(value)), Scoping.UNSCOPED);
@@ -1066,26 +1074,32 @@ final class InjectorImpl implements Injector, Lookups {
             return provider;
         }
 
+        @Override
         public <V> V acceptTargetVisitor(BindingTargetVisitor<? super T, V> visitor) {
             return visitor.visit(this);
         }
 
+        @Override
         public T getValue() {
             return value;
         }
 
+        @Override
         public TypeConverterBinding getTypeConverterBinding() {
             return typeConverterBinding;
         }
 
+        @Override
         public Key<String> getSourceKey() {
             return originalBinding.getKey();
         }
 
+        @Override
         public Set<Dependency<?>> getDependencies() {
             return ImmutableSet.<Dependency<?>>of(Dependency.get(getSourceKey()));
         }
 
+        @Override
         public void applyTo(Binder binder) {
             throw new UnsupportedOperationException("This element represents a synthetic binding.");
         }
@@ -1116,27 +1130,4 @@ final class InjectorImpl implements Injector, Lookups {
             return Objects.hashCode(getKey(), getScoping(), value);
         }
     }
-
-    private static class BindingsMultimap {
-        final Map<TypeLiteral<?>, List<Binding<?>>> multimap = Maps.newHashMap();
-
-        <T> void put(TypeLiteral<T> type, Binding<T> binding) {
-            List<Binding<?>> bindingsForType = multimap.get(type);
-            if (bindingsForType == null) {
-                bindingsForType = Lists.newArrayList();
-                multimap.put(type, bindingsForType);
-            }
-            bindingsForType.add(binding);
-        }
-
-
-        @SuppressWarnings("unchecked")
-            // safe because we only put matching entries into the map
-        <T> List<Binding<T>> getAll(TypeLiteral<T> type) {
-            List<Binding<?>> bindings = multimap.get(type);
-            return bindings != null
-                    ? Collections.<Binding<T>>unmodifiableList((List) multimap.get(type))
-                    : ImmutableList.<Binding<T>>of();
-        }
-    }
 }

src/main/java/com/google/inject/internal/InjectorShell.java

@@ -15,7 +15,6 @@ import com.google.inject.internal.util.Stopwatch;
 import com.google.inject.spi.Dependency;
 import com.google.inject.spi.Element;
 import com.google.inject.spi.Elements;
-import com.google.inject.spi.InjectionPoint;
 import com.google.inject.spi.ModuleAnnotatedMethodScannerBinding;
 import com.google.inject.spi.PrivateElements;
 import com.google.inject.spi.ProvisionListenerBinding;
@@ -35,11 +34,20 @@ final class InjectorShell {
     private final List<Element> elements;
     private final InjectorImpl injector;
 
-    private InjectorShell(Builder builder, List<Element> elements, InjectorImpl injector) {
+    private InjectorShell(List<Element> elements, InjectorImpl injector) {
         this.elements = elements;
         this.injector = injector;
     }
 
+    InjectorImpl getInjector() {
+        return injector;
+    }
+
+    List<Element> getElements() {
+        return elements;
+    }
+
+
     /**
      * The Injector is a special case because we allow both parent and child injectors to both have
      * a binding for that key.
@@ -48,44 +56,23 @@ final class InjectorShell {
         Key<Injector> key = Key.get(Injector.class);
         InjectorFactory injectorFactory = new InjectorFactory(injector);
         injector.state.putBinding(key,
-                new ProviderInstanceBindingImpl<Injector>(injector, key, SourceProvider.UNKNOWN_SOURCE,
+                new ProviderInstanceBindingImpl<>(injector, key, SourceProvider.UNKNOWN_SOURCE,
                         injectorFactory, Scoping.UNSCOPED, injectorFactory,
-                        ImmutableSet.<InjectionPoint>of()));
+                        ImmutableSet.of()));
     }
 
-    /**
-     * The Logger is a special case because it knows the injection point of the injected member. It's
-     * the only binding that does this.
-     */
-    /*private static void bindLogger(InjectorImpl injector) {
-        Key<Logger> key = Key.get(Logger.class);
-        LoggerFactory loggerFactory = new LoggerFactory();
-        injector.state.putBinding(key,
-                new ProviderInstanceBindingImpl<Logger>(injector, key,
-                        SourceProvider.UNKNOWN_SOURCE, loggerFactory, Scoping.UNSCOPED,
-                        loggerFactory, ImmutableSet.<InjectionPoint>of()));
-    }*/
-
     private static void bindStage(InjectorImpl injector, Stage stage) {
         Key<Stage> key = Key.get(Stage.class);
-        InstanceBindingImpl<Stage> stageBinding = new InstanceBindingImpl<Stage>(
+        InstanceBindingImpl<Stage> stageBinding = new InstanceBindingImpl<>(
                 injector,
                 key,
                 SourceProvider.UNKNOWN_SOURCE,
-                new ConstantFactory<Stage>(Initializables.of(stage)),
+                new ConstantFactory<>(Initializables.of(stage)),
-                ImmutableSet.<InjectionPoint>of(),
+                ImmutableSet.of(),
                 stage);
         injector.state.putBinding(key, stageBinding);
     }
 
-    InjectorImpl getInjector() {
-        return injector;
-    }
-
-    List<Element> getElements() {
-        return elements;
-    }
-
     static class Builder {
         private final List<Element> elements = Lists.newArrayList();
         private final List<Module> modules = Lists.newArrayList();
@@ -213,7 +200,7 @@ final class InjectorShell {
             stopwatch.resetAndLog("Module annotated method scanners creation");
 
             List<InjectorShell> injectorShells = Lists.newArrayList();
-            injectorShells.add(new InjectorShell(this, elements, injector));
+            injectorShells.add(new InjectorShell(elements, injector));
 
             // recursively build child shells
             PrivateElementProcessor processor = new PrivateElementProcessor(errors);
@@ -241,11 +228,12 @@ final class InjectorShell {
             this.injector = injector;
         }
 
-        public Injector get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked)
+        @Override
-                throws ErrorsException {
+        public Injector get(InternalContext context, Dependency<?> dependency, boolean linked) {
             return injector;
         }
 
+        @Override
         public Injector get() {
             return injector;
         }
@@ -255,24 +243,8 @@ final class InjectorShell {
         }
     }
 
-    /*private static class LoggerFactory implements InternalFactory<Logger>, Provider<Logger> {
-        public Logger get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked) {
-            InjectionPoint injectionPoint = dependency.getInjectionPoint();
-            return injectionPoint == null
-                    ? Logger.getAnonymousLogger()
-                    : Logger.getLogger(injectionPoint.getMember().getDeclaringClass().getName());
-        }
-
-        public Logger get() {
-            return Logger.getAnonymousLogger();
-        }
-
-        public String toString() {
-            return "Provider<Logger>";
-        }
-    }*/
-
     private static class RootModule implements Module {
+        @Override
         public void configure(Binder binder) {
             binder = binder.withSource(SourceProvider.UNKNOWN_SOURCE);
             binder.bindScope(Singleton.class, SINGLETON);
@@ -287,6 +259,7 @@ final class InjectorShell {
             this.state = state;
         }
 
+        @Override
         public void configure(Binder binder) {
             for (ModuleAnnotatedMethodScannerBinding binding : state.getScannerBindings()) {
                 binding.applyTo(binder);

src/main/java/com/google/inject/internal/InstanceBindingImpl.java

@@ -5,20 +5,17 @@ import com.google.common.base.Objects;
 import com.google.common.collect.ImmutableSet;
 import com.google.inject.Binder;
 import com.google.inject.Key;
-import com.google.inject.Provider;
 import com.google.inject.spi.BindingTargetVisitor;
 import com.google.inject.spi.Dependency;
 import com.google.inject.spi.HasDependencies;
 import com.google.inject.spi.InjectionPoint;
 import com.google.inject.spi.InstanceBinding;
-import com.google.inject.util.Providers;
 
 import java.util.Set;
 
 final class InstanceBindingImpl<T> extends BindingImpl<T> implements InstanceBinding<T> {
 
     final T instance;
-    final Provider<T> provider;
     final ImmutableSet<InjectionPoint> injectionPoints;
 
     public InstanceBindingImpl(InjectorImpl injector, Key<T> key, Object source,
@@ -27,7 +24,6 @@ final class InstanceBindingImpl<T> extends BindingImpl<T> implements InstanceBin
         super(injector, key, source, internalFactory, Scoping.EAGER_SINGLETON);
         this.injectionPoints = ImmutableSet.copyOf(injectionPoints);
         this.instance = instance;
-        this.provider = Providers.of(instance);
     }
 
     public InstanceBindingImpl(Object source, Key<T> key, Scoping scoping,
@@ -35,40 +31,41 @@ final class InstanceBindingImpl<T> extends BindingImpl<T> implements InstanceBin
         super(source, key, scoping);
         this.injectionPoints = ImmutableSet.copyOf(injectionPoints);
         this.instance = instance;
-        this.provider = Providers.of(instance);
     }
 
     @Override
-    public Provider<T> getProvider() {
-        return this.provider;
-    }
-
     public <V> V acceptTargetVisitor(BindingTargetVisitor<? super T, V> visitor) {
         return visitor.visit(this);
     }
 
+    @Override
     public T getInstance() {
         return instance;
     }
 
+    @Override
     public Set<InjectionPoint> getInjectionPoints() {
         return injectionPoints;
     }
 
+    @Override
     public Set<Dependency<?>> getDependencies() {
         return instance instanceof HasDependencies
                 ? ImmutableSet.copyOf(((HasDependencies) instance).getDependencies())
                 : Dependency.forInjectionPoints(injectionPoints);
     }
 
+    @Override
     public BindingImpl<T> withScoping(Scoping scoping) {
         return new InstanceBindingImpl<T>(getSource(), getKey(), scoping, injectionPoints, instance);
     }
 
+    @Override
     public BindingImpl<T> withKey(Key<T> key) {
         return new InstanceBindingImpl<T>(getSource(), key, getScoping(), injectionPoints, instance);
     }
 
+    @Override
     public void applyTo(Binder binder) {
         // instance bindings aren't scoped
         binder.withSource(getSource()).bind(getKey()).toInstance(instance);

src/main/java/com/google/inject/internal/InternalContext.java

@@ -1,37 +1,76 @@
 package com.google.inject.internal;
 
-import com.google.common.collect.ImmutableList;
-import com.google.common.collect.Maps;
 import com.google.inject.Key;
 import com.google.inject.internal.InjectorImpl.InjectorOptions;
 import com.google.inject.spi.Dependency;
-import com.google.inject.spi.DependencyAndSource;
 
-import java.util.Arrays;
+import java.util.IdentityHashMap;
-import java.util.List;
 import java.util.Map;
 
 /**
  * Internal context. Used to coordinate injections and support circular
  * dependencies.
  */
-final class InternalContext {
+final class InternalContext implements AutoCloseable {
 
     private final InjectorOptions options;
-    /**
+
-     * Keeps track of the hierarchy of types needed during injection.
+    private final Map<Object, ConstructionContext<?>> constructionContexts =
-     */
+            new IdentityHashMap<>();
-    private final DependencyStack state = new DependencyStack();
+
-    private Map<Object, ConstructionContext<?>> constructionContexts = Maps.newHashMap();
     /**
      * Keeps track of the type that is currently being requested for injection.
      */
     private Dependency<?> dependency;
 
-    InternalContext(InjectorOptions options) {
+    /**
+     * Keeps track of the hierarchy of types needed during injection.
+     *
+     * <p>This is a pairwise combination of dependencies and sources, with dependencies or keys on
+     * even indices, and sources on odd indices. This structure is to avoid the memory overhead of
+     * DependencyAndSource objects, which can add to several tens of megabytes in large applications.
+     */
+    private Object[] dependencyStack = new Object[16];
+
+    private int dependencyStackSize = 0;
+
+    /**
+     * The number of times {@link #enter()} has been called + 1 for initial construction.
+     */
+    private int enterCount;
+
+    /**
+     * A single element array to clear when the {@link #enterCount} hits {@code 0}.
+     *
+     * <p>This is the value stored in the {@code InjectorImpl.localContext} thread local.
+     */
+    private final Object[] toClear;
+
+    InternalContext(InjectorOptions options, Object[] toClear) {
         this.options = options;
+        this.toClear = toClear;
+        this.enterCount = 1;
     }
 
+
+    /** Should only be called by InjectorImpl.enterContext(). */
+    void enter() {
+        enterCount++;
+    }
+
+    /** Should be called any any method that received an instance via InjectorImpl.enterContext(). */
+    @Override
+    public void close() {
+        int newCount = --enterCount;
+        if (newCount < 0) {
+            throw new IllegalStateException("Called close() too many times");
+        }
+        if (newCount == 0) {
+            toClear[0] = null;
+        }
+    }
+
+
     public InjectorOptions getInjectorOptions() {
         return options;
     }
@@ -57,7 +96,7 @@ final class InternalContext {
     public Dependency<?> pushDependency(Dependency<?> dependency, Object source) {
         Dependency<?> previous = this.dependency;
         this.dependency = dependency;
-        state.add(dependency, source);
+        doPushState(dependency, source);
         return previous;
     }
 
@@ -65,7 +104,7 @@ final class InternalContext {
      * Pops the current state & sets the new dependency.
      */
     public void popStateAndSetDependency(Dependency<?> newDependency) {
-        state.pop();
+        popState();
         this.dependency = newDependency;
     }
 
@@ -73,64 +112,29 @@ final class InternalContext {
      * Adds to the state without setting the dependency.
      */
     public void pushState(Key<?> key, Object source) {
-        state.add(key, source);
+        doPushState(key, source);
+    }
+
+    private void doPushState(Object dependencyOrKey, Object source) {
+        int localSize = dependencyStackSize;
+        Object[] localStack = dependencyStack;
+        if (localStack.length < localSize + 2) {
+            localStack = dependencyStack =
+                    java.util.Arrays.copyOf(localStack, (localStack.length * 3) / 2 + 2);
+        }
+        localStack[localSize++] = dependencyOrKey;
+        localStack[localSize++] = source;
+        dependencyStackSize = localSize;
     }
 
     /**
      * Pops from the state without setting a dependency.
      */
     public void popState() {
-        state.pop();
+        // N.B. we don't null out the array entries.  It isn't necessary since all the objects in the
-    }
+        // array (Key, Dependency, or Binding source objects) are all tied to the lifetime of the
-
+        // injector, which is greater than the lifetime of this object.  So removing them from the array
-    /**
+        // doesn't matter.
-     * Returns the current dependency chain (all the state).
+        dependencyStackSize -= 2;
-     */
-    public List<DependencyAndSource> getDependencyChain() {
-        ImmutableList.Builder<DependencyAndSource> builder = ImmutableList.builder();
-        for (int i = 0; i < state.size(); i += 2) {
-            Object evenEntry = state.get(i);
-            Dependency<?> dependency;
-            if (evenEntry instanceof Key) {
-                dependency = Dependency.get((Key<?>) evenEntry);
-            } else {
-                dependency = (Dependency<?>) evenEntry;
-            }
-            builder.add(new DependencyAndSource(dependency, state.get(i + 1)));
-        }
-        return builder.build();
-    }
-
-    /**
-     * Keeps track of the hierarchy of types needed during injection.
-     *
-     * <p>This is a pairwise combination of dependencies and sources, with dependencies or keys on
-     * even indices, and sources on odd indices. This structure is to avoid the memory overhead of
-     * DependencyAndSource objects, which can add to several tens of megabytes in large applications.
-     */
-    private static final class DependencyStack {
-        private Object[] elements = new Object[16];
-        private int size = 0;
-
-        public void add(Object dependencyOrKey, Object source) {
-            if (elements.length < size + 2) {
-                elements = Arrays.copyOf(elements, (elements.length * 3) / 2 + 2);
-            }
-            elements[size++] = dependencyOrKey;
-            elements[size++] = source;
-        }
-
-        public void pop() {
-            elements[--size] = null;
-            elements[--size] = null;
-        }
-
-        public Object get(int i) {
-            return elements[i];
-        }
-
-        public int size() {
-            return size;
-        }
     }
 }

src/main/java/com/google/inject/internal/InternalFactory.java

@@ -12,9 +12,9 @@ interface InternalFactory<T> {
      *
      * @param context of this injection
      * @param linked  true if getting as a result of a linked binding
-     * @return instance to be injected
+     * @return instance that was created
-     * @throws com.google.inject.internal.ErrorsException if a value cannot be provided
+     * @throws InternalProvisionException if a value cannot be provided
      */
-    T get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked)
+    T get(InternalContext context, Dependency<?> dependency, boolean linked)
-            throws ErrorsException;
+            throws InternalProvisionException;
 }

src/main/java/com/google/inject/internal/InternalFactoryToInitializableAdapter.java

@@ -14,7 +14,7 @@ final class InternalFactoryToInitializableAdapter<T> extends ProviderInternalFac
     private final ProvisionListenerStackCallback<T> provisionCallback;
     private final Initializable<? extends javax.inject.Provider<? extends T>> initializable;
 
-    public InternalFactoryToInitializableAdapter(
+    InternalFactoryToInitializableAdapter(
             Initializable<? extends javax.inject.Provider<? extends T>> initializable,
             Object source, ProvisionListenerStackCallback<T> provisionCallback) {
         super(source);
@@ -22,19 +22,20 @@ final class InternalFactoryToInitializableAdapter<T> extends ProviderInternalFac
         this.initializable = checkNotNull(initializable, "provider");
     }
 
-    public T get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked)
+    @Override
-            throws ErrorsException {
+    public T get(InternalContext context, Dependency<?> dependency, boolean linked)
-        return circularGet(initializable.get(errors), errors, context, dependency,
+            throws InternalProvisionException {
-                provisionCallback);
+        return circularGet(initializable.get(), context, dependency, provisionCallback);
     }
 
     @Override
-    protected T provision(javax.inject.Provider<? extends T> provider, Errors errors,
+    protected T provision(javax.inject.Provider<? extends T> provider,
-                          Dependency<?> dependency, ConstructionContext<T> constructionContext) throws ErrorsException {
+                          Dependency<?> dependency,
+                          ConstructionContext<T> constructionContext) throws InternalProvisionException {
         try {
-            return super.provision(provider, errors, dependency, constructionContext);
+            return super.provision(provider, dependency, constructionContext);
         } catch (RuntimeException userException) {
-            throw errors.withSource(source).errorInProvider(userException).toException();
+            throw InternalProvisionException.errorInProvider(userException).addSource(source);
         }
     }
 

src/main/java/com/google/inject/internal/InternalFactoryToProviderAdapter.java

@@ -10,18 +10,22 @@ final class InternalFactoryToProviderAdapter<T> implements InternalFactory<T> {
     private final Provider<? extends T> provider;
     private final Object source;
 
-    public InternalFactoryToProviderAdapter(Provider<? extends T> provider, Object source) {
+    InternalFactoryToProviderAdapter(Provider<? extends T> provider, Object source) {
         this.provider = checkNotNull(provider, "provider");
         this.source = checkNotNull(source, "source");
     }
 
-    public T get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked)
+    @Override
-            throws ErrorsException {
+    public T get(InternalContext context, Dependency<?> dependency, boolean linked)
-        // TODO(sameb): Does this need to push state into the context?
+            throws InternalProvisionException {
         try {
-            return errors.checkForNull(provider.get(), source, dependency);
+            T t = provider.get();
+            if (t == null && !dependency.isNullable()) {
+                InternalProvisionException.onNullInjectedIntoNonNullableDependency(source, dependency);
+            }
+            return t;
         } catch (RuntimeException userException) {
-            throw errors.withSource(source).errorInProvider(userException).toException();
+            throw InternalProvisionException.errorInProvider(userException).addSource(source);
         }
     }
 

src/main/java/com/google/inject/internal/InternalFlags.java

@@ -66,19 +66,13 @@ public class InternalFlags {
     private static <T extends Enum<T>> T getSystemOption(final String name, T defaultValue,
                                                          T secureValue) {
         Class<T> enumType = defaultValue.getDeclaringClass();
-        String value = null;
         try {
-            value = AccessController.doPrivileged(new PrivilegedAction<String>() {
+            String value = AccessController.doPrivileged((PrivilegedAction<String>) ()
-                public String run() {
+                    -> System.getProperty(name));
-                    return System.getProperty(name);
-                }
-            });
             return (value != null && value.length() > 0) ? Enum.valueOf(enumType, value) : defaultValue;
         } catch (SecurityException e) {
             return secureValue;
         } catch (IllegalArgumentException e) {
-            //logger.warning(value + " is not a valid flag value for " + name + ". "
-            //        + " Values must be one of " + Arrays.asList(enumType.getEnumConstants()));
             return defaultValue;
         }
     }

src/main/java/com/google/inject/internal/InternalInjectorCreator.java

@@ -1,7 +1,5 @@
 package com.google.inject.internal;
 
-import com.google.common.collect.ImmutableList;
-import com.google.common.collect.Iterables;
 import com.google.inject.Binding;
 import com.google.inject.Injector;
 import com.google.inject.Key;
@@ -13,9 +11,12 @@ import com.google.inject.Stage;
 import com.google.inject.TypeLiteral;
 import com.google.inject.internal.util.Stopwatch;
 import com.google.inject.spi.Dependency;
+import com.google.inject.spi.Element;
+import com.google.inject.spi.InjectionPoint;
 import com.google.inject.spi.TypeConverterBinding;
 
 import java.lang.annotation.Annotation;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
@@ -64,7 +65,7 @@ public final class InternalInjectorCreator {
      * Sets the parent of the injector to-be-constructed. As a side effect, this sets this injector's
      * stage to the stage of {@code parent}.
      */
-    public InternalInjectorCreator parentInjector(InjectorImpl parent) {
+    InternalInjectorCreator parentInjector(InjectorImpl parent) {
         shellBuilder.parent(parent);
         return this;
     }
@@ -102,36 +103,32 @@ public final class InternalInjectorCreator {
     private void initializeStatically() {
         bindingData.initializeBindings();
         stopwatch.resetAndLog("Binding initialization");
-
         for (InjectorShell shell : shells) {
             shell.getInjector().index();
         }
         stopwatch.resetAndLog("Binding indexing");
-
         injectionRequestProcessor.process(shells);
         stopwatch.resetAndLog("Collecting injection requests");
-
         bindingData.runCreationListeners(errors);
         stopwatch.resetAndLog("Binding validation");
-
         injectionRequestProcessor.validate();
         stopwatch.resetAndLog("Static validation");
-
         initializer.validateOustandingInjections(errors);
         stopwatch.resetAndLog("Instance member validation");
-
         new LookupProcessor(errors).process(shells);
         for (InjectorShell shell : shells) {
             ((DeferredLookups) shell.getInjector().lookups).initialize(errors);
         }
         stopwatch.resetAndLog("Provider verification");
-
+        // This needs to come late since some user bindings rely on requireBinding calls to create
+        // jit bindings during the LookupProcessor.
+        bindingData.initializeDelayedBindings();
+        stopwatch.resetAndLog("Delayed Binding initialization");
         for (InjectorShell shell : shells) {
             if (!shell.getElements().isEmpty()) {
                 throw new AssertionError("Failed to execute " + shell.getElements());
             }
         }
-
         errors.throwCreationExceptionIfErrorsExist();
     }
 
@@ -170,31 +167,25 @@ public final class InternalInjectorCreator {
      */
     void loadEagerSingletons(InjectorImpl injector, Stage stage, final Errors errors) {
         @SuppressWarnings("unchecked") // casting Collection<Binding> to Collection<BindingImpl> is safe
-                Iterable<BindingImpl<?>> candidateBindings = ImmutableList.copyOf(Iterables.concat(
+        Collection<BindingImpl<?>> bindingsAtThisLevel =
-                (Collection) injector.state.getExplicitBindingsThisLevel().values(),
+                (Collection) injector.state.getExplicitBindingsThisLevel().values();
-                injector.jitBindings.values()));
+        List<BindingImpl<?>> candidateBindings = new ArrayList<>(bindingsAtThisLevel);
-        for (final BindingImpl<?> binding : candidateBindings) {
+        synchronized (injector.state.lock()) {
+            // jit bindings must be accessed while holding the lock.
+            candidateBindings.addAll(injector.jitBindings.values());
+        }
+        try (InternalContext context = injector.enterContext()) {
+            for (BindingImpl<?> binding : candidateBindings) {
                 if (isEagerSingleton(injector, binding, stage)) {
-                try {
-                    injector.callInContext(new ContextualCallable<Void>() {
                     Dependency<?> dependency = Dependency.get(binding.getKey());
-
+                    Dependency<?> previous = context.pushDependency(dependency, binding.getSource());
-                        public Void call(InternalContext context) {
-                            Dependency previous = context.pushDependency(dependency, binding.getSource());
-                            Errors errorsForBinding = errors.withSource(dependency);
                     try {
-                                binding.getInternalFactory().get(errorsForBinding, context, dependency, false);
+                        binding.getInternalFactory().get(context, dependency, false);
-                            } catch (ErrorsException e) {
+                    } catch (InternalProvisionException e) {
-                                errorsForBinding.merge(e.getErrors());
+                        errors.withSource(dependency).merge(e);
                     } finally {
                         context.popStateAndSetDependency(previous);
                     }
-
-                            return null;
-                        }
-                    });
-                } catch (ErrorsException e) {
-                    throw new AssertionError();
                 }
             }
         }
@@ -207,10 +198,11 @@ public final class InternalInjectorCreator {
 
         // handle a corner case where a child injector links to a binding in a parent injector, and
         // that binding is singleton. We won't catch this otherwise because we only iterate the child's
-        // bindings.
+        // bindings. This only applies if the linked binding is not itself scoped.
         if (binding instanceof LinkedBindingImpl) {
             Key<?> linkedBinding = ((LinkedBindingImpl<?>) binding).getLinkedKey();
-            return isEagerSingleton(injector, injector.getBinding(linkedBinding), stage);
+            return binding.getScoping().isNoScope() &&
+                    isEagerSingleton(injector, injector.getBinding(linkedBinding), stage);
         }
 
         return false;
@@ -226,80 +218,108 @@ public final class InternalInjectorCreator {
             this.delegateInjector = delegateInjector;
         }
 
+        @Override
         public void injectMembers(Object o) {
             throw new UnsupportedOperationException(
                     "Injector.injectMembers(Object) is not supported in Stage.TOOL");
         }
 
+        @Override
         public Map<Key<?>, Binding<?>> getBindings() {
             return this.delegateInjector.getBindings();
         }
 
+        @Override
         public Map<Key<?>, Binding<?>> getAllBindings() {
             return this.delegateInjector.getAllBindings();
         }
 
+        @Override
         public <T> Binding<T> getBinding(Key<T> key) {
             return this.delegateInjector.getBinding(key);
         }
 
+        @Override
         public <T> Binding<T> getBinding(Class<T> type) {
             return this.delegateInjector.getBinding(type);
         }
 
+        @Override
         public <T> Binding<T> getExistingBinding(Key<T> key) {
             return this.delegateInjector.getExistingBinding(key);
         }
 
+        @Override
         public <T> List<Binding<T>> findBindingsByType(TypeLiteral<T> type) {
             return this.delegateInjector.findBindingsByType(type);
         }
 
+        @Override
         public Injector getParent() {
             return delegateInjector.getParent();
         }
 
+        @Override
         public Injector createChildInjector(Iterable<? extends Module> modules) {
             return delegateInjector.createChildInjector(modules);
         }
 
+        @Override
         public Injector createChildInjector(Module... modules) {
             return delegateInjector.createChildInjector(modules);
         }
 
+        @Override
         public Map<Class<? extends Annotation>, Scope> getScopeBindings() {
             return delegateInjector.getScopeBindings();
         }
 
+        @Override
         public Set<TypeConverterBinding> getTypeConverterBindings() {
             return delegateInjector.getTypeConverterBindings();
         }
 
+        @Override
+        public List<Element> getElements() {
+            return delegateInjector.getElements();
+        }
+
+        @Override
+        public Map<TypeLiteral<?>, List<InjectionPoint>> getAllMembersInjectorInjectionPoints() {
+            return delegateInjector.getAllMembersInjectorInjectionPoints();
+        }
+
+        @Override
         public <T> Provider<T> getProvider(Key<T> key) {
             throw new UnsupportedOperationException(
                     "Injector.getProvider(Key<T>) is not supported in Stage.TOOL");
         }
 
+        @Override
         public <T> Provider<T> getProvider(Class<T> type) {
             throw new UnsupportedOperationException(
                     "Injector.getProvider(Class<T>) is not supported in Stage.TOOL");
         }
 
+        @Override
         public <T> MembersInjector<T> getMembersInjector(TypeLiteral<T> typeLiteral) {
             throw new UnsupportedOperationException(
                     "Injector.getMembersInjector(TypeLiteral<T>) is not supported in Stage.TOOL");
         }
 
+        @Override
         public <T> MembersInjector<T> getMembersInjector(Class<T> type) {
             throw new UnsupportedOperationException(
                     "Injector.getMembersInjector(Class<T>) is not supported in Stage.TOOL");
         }
 
+        @Override
         public <T> T getInstance(Key<T> key) {
             throw new UnsupportedOperationException(
                     "Injector.getInstance(Key<T>) is not supported in Stage.TOOL");
         }
 
+        @Override
         public <T> T getInstance(Class<T> type) {
             throw new UnsupportedOperationException(
                     "Injector.getInstance(Class<T>) is not supported in Stage.TOOL");

src/main/java/com/google/inject/internal/InternalProviderInstanceBindingImpl.java

@@ -0,0 +1,179 @@
+package com.google.inject.internal;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.inject.Key;
+import com.google.inject.Provider;
+import com.google.inject.spi.Dependency;
+import com.google.inject.spi.HasDependencies;
+import com.google.inject.spi.ProviderWithExtensionVisitor;
+
+/**
+ * A {@link ProviderInstanceBindingImpl} for implementing 'native' guice extensions.
+ *
+ * <p>Beyond the normal binding contract that is mostly handled by our baseclass, this also
+ * implements {@link DelayedInitialize} in order to initialize factory state.
+ */
+final class InternalProviderInstanceBindingImpl<T> extends ProviderInstanceBindingImpl<T>
+        implements DelayedInitialize {
+    enum InitializationTiming {
+        /** This factory can be initialized eagerly. This should be the case for most things. */
+        EAGER,
+
+        /**
+         * Initialization of this factory should be delayed until after all other static initialization
+         * completes. This will be useful for factories that need to call {@link
+         * InjectorImpl#getExistingBinding(Key)} to not create jit bindings, but also want to be able to
+         * conditionally consume jit bindings created by other other bindings.
+         */
+        DELAYED
+    }
+
+    private final Factory<T> originalFactory;
+
+    InternalProviderInstanceBindingImpl(
+            InjectorImpl injector,
+            Key<T> key,
+            Object source,
+            Factory<T> originalFactory,
+            InternalFactory<? extends T> scopedFactory,
+            Scoping scoping) {
+        super(
+                injector,
+                key,
+                source,
+                scopedFactory,
+                scoping,
+                originalFactory,
+                ImmutableSet.of());
+        this.originalFactory = originalFactory;
+    }
+
+    InitializationTiming getInitializationTiming() {
+        return originalFactory.initializationTiming;
+    }
+
+    @Override
+    public void initialize(final InjectorImpl injector, final Errors errors) throws ErrorsException {
+        originalFactory.source = getSource();
+        originalFactory.provisionCallback = injector.provisionListenerStore.get(this);
+        // For these kinds of providers, the 'user supplied provider' is really 'guice supplied'
+        // So make our user supplied provider just delegate to the guice supplied one.
+        originalFactory.delegateProvider = getProvider();
+        originalFactory.initialize(injector, errors);
+    }
+
+    /**
+     * A base factory implementation. Any Factories that delegate to other bindings should use the
+     * {@code CyclicFactory} subclass, but trivial factories can use this one.
+     */
+    abstract static class Factory<T> implements InternalFactory<T>, Provider<T>, HasDependencies {
+        private final InitializationTiming initializationTiming;
+        private Object source;
+        private Provider<T> delegateProvider;
+        ProvisionListenerStackCallback<T> provisionCallback;
+
+        Factory(InitializationTiming initializationTiming) {
+            this.initializationTiming = initializationTiming;
+        }
+        /**
+         * The binding source.
+         *
+         * <p>May be useful for augmenting runtime error messages.
+         *
+         * <p>Note: this will return {#code null} until {@link #initialize(InjectorImpl, Errors)} has
+         * already been called.
+         */
+        final Object getSource() {
+            return source;
+        }
+
+        /**
+         * A callback that allows for implementations to fetch dependencies on other bindings.
+         *
+         * <p>Will be called exactly once, prior to any call to {@link #doProvision}.
+         */
+        abstract void initialize(InjectorImpl injector, Errors errors) throws ErrorsException;
+
+        @Override
+        public final T get() {
+            Provider<T> local = delegateProvider;
+            if (local == null) {
+                throw new IllegalStateException(
+                        "This Provider cannot be used until the Injector has been created.");
+            }
+            return local.get();
+        }
+
+        @Override
+        public T get(final InternalContext context, final Dependency<?> dependency, boolean linked)
+                throws InternalProvisionException {
+            if (provisionCallback == null) {
+                return doProvision(context, dependency);
+            } else {
+                return provisionCallback.provision(context, () -> doProvision(context, dependency));
+            }
+        }
+        /**
+         * Creates an object to be injected.
+         *
+         * @throws com.google.inject.internal.InternalProvisionException if a value cannot be provided
+         * @return instance to be injected
+         */
+        protected abstract T doProvision(InternalContext context, Dependency<?> dependency)
+                throws InternalProvisionException;
+    }
+
+    /**
+     * An base factory implementation that can be extended to provide a specialized implementation of
+     * a {@link ProviderWithExtensionVisitor} and also implements {@link InternalFactory}
+     */
+    abstract static class CyclicFactory<T> extends Factory<T> {
+
+        CyclicFactory(InitializationTiming initializationTiming) {
+            super(initializationTiming);
+        }
+
+        @Override
+        public final T get(
+                final InternalContext context, final Dependency<?> dependency, boolean linked)
+                throws InternalProvisionException {
+            final ConstructionContext<T> constructionContext = context.getConstructionContext(this);
+            // We have a circular reference between bindings. Return a proxy.
+            if (constructionContext.isConstructing()) {
+                Class<?> expectedType = dependency.getKey().getTypeLiteral().getRawType();
+                @SuppressWarnings("unchecked")
+                T proxyType =
+                        (T) constructionContext.createProxy(context.getInjectorOptions(), expectedType);
+                return proxyType;
+            }
+            // Optimization: Don't go through the callback stack if no one's listening.
+            constructionContext.startConstruction();
+            try {
+                if (provisionCallback == null) {
+                    return provision(dependency, context, constructionContext);
+                } else {
+                    return provisionCallback.provision(context, () -> provision(dependency, context, constructionContext));
+                }
+            } finally {
+                constructionContext.removeCurrentReference();
+                constructionContext.finishConstruction();
+            }
+        }
+
+        private T provision(
+                Dependency<?> dependency,
+                InternalContext context,
+                ConstructionContext<T> constructionContext)
+                throws InternalProvisionException {
+            try {
+                T t = doProvision(context, dependency);
+                constructionContext.setProxyDelegates(t);
+                return t;
+            } catch (InternalProvisionException ipe) {
+                throw ipe.addSource(getSource());
+            } catch (Throwable t) {
+                throw InternalProvisionException.errorInProvider(t).addSource(getSource());
+            }
+        }
+    }
+}

src/main/java/com/google/inject/internal/InternalProvisionException.java

@@ -0,0 +1,216 @@
+package com.google.inject.internal;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Lists;
+import com.google.inject.Guice;
+import com.google.inject.Key;
+import com.google.inject.MembersInjector;
+import com.google.inject.Provides;
+import com.google.inject.ProvisionException;
+import com.google.inject.TypeLiteral;
+import com.google.inject.internal.util.SourceProvider;
+import com.google.inject.internal.util.StackTraceElements;
+import com.google.inject.spi.Dependency;
+import com.google.inject.spi.InjectionListener;
+import com.google.inject.spi.Message;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * A checked exception for provisioning errors.
+ *
+ * <p>This is the internal dual of {@link ProvisionException}, similar to the relationship between
+ * {@link com.google.inject.ConfigurationException} and {@link ErrorsException}. This is useful for
+ * several reasons:
+ *
+ * <ul>
+ *   <li>Since it is a checked exception, we get some assistance from the java compiler in ensuring
+ *       that we correctly handle it everywhere. ProvisionException is unchecked.
+ *   <li>Since this is an internal package, we can add useful construction and mutation APIs that
+ *       would be undesirable in a public supported API.
+ * </ul>
+ *
+ * <p>This exception will be thrown when errors are encountered during provisioning, ErrorsException
+ * will continue to be used for errors that are encountered during provisioning and both make use of
+ * the {@link Message} as the core model.
+ *
+ * <p>NOTE: this object stores a list of messages but in the most common case the cardinality will
+ * be 1. The only time that multiple errors might be reported via this mechanism is when {@link
+ * #errorInUserCode} is called with an exception that holds multiple errors (like
+ * ProvisionException).
+ */
+@SuppressWarnings("serial")
+public final class InternalProvisionException extends Exception {
+
+  private static final Logger logger = Logger.getLogger(Guice.class.getName());
+
+  private static final Set<Dependency<?>> warnedDependencies =
+      Collections.newSetFromMap(new ConcurrentHashMap<>());
+
+
+  public static InternalProvisionException circularDependenciesDisabled(Class<?> expectedType) {
+    return create(
+        "Found a circular dependency involving %s, and circular dependencies are disabled.",
+        expectedType);
+  }
+
+  public static InternalProvisionException cannotProxyClass(Class<?> expectedType) {
+    return create(
+        "Tried proxying %s to support a circular dependency, but it is not an interface.",
+        expectedType);
+  }
+
+  public static InternalProvisionException create(String format, Object... arguments) {
+    return new InternalProvisionException(Messages.create(format, arguments));
+  }
+
+  public static InternalProvisionException errorInUserCode(
+      Throwable cause, String messageFormat, Object... arguments) {
+    Collection<Message> messages = Errors.getMessagesFromThrowable(cause);
+    if (!messages.isEmpty()) {
+      // TODO(lukes): it seems like we are dropping some valuable context here..
+      // consider eliminating this special case
+      return new InternalProvisionException(messages);
+    } else {
+      return new InternalProvisionException(Messages.create(cause, messageFormat, arguments));
+    }
+  }
+
+  public static InternalProvisionException subtypeNotProvided(
+      Class<? extends javax.inject.Provider<?>> providerType, Class<?> type) {
+    return create("%s doesn't provide instances of %s.", providerType, type);
+  }
+
+  public static InternalProvisionException errorInProvider(Throwable cause) {
+    return errorInUserCode(cause, "Error in custom provider, %s", cause);
+  }
+
+  public static InternalProvisionException errorInjectingMethod(Throwable cause) {
+    return errorInUserCode(cause, "Error injecting method, %s", cause);
+  }
+
+  public static InternalProvisionException errorInjectingConstructor(Throwable cause) {
+    return errorInUserCode(cause, "Error injecting constructor, %s", cause);
+  }
+
+  public static InternalProvisionException errorInUserInjector(
+      MembersInjector<?> listener, TypeLiteral<?> type, RuntimeException cause) {
+    return errorInUserCode(
+        cause, "Error injecting %s using %s.%n Reason: %s", type, listener, cause);
+  }
+
+  public static InternalProvisionException jitDisabled(Key<?> key) {
+    return create("Explicit bindings are required and %s is not explicitly bound.", key);
+  }
+
+  public static InternalProvisionException errorNotifyingInjectionListener(
+      InjectionListener<?> listener, TypeLiteral<?> type, RuntimeException cause) {
+    return errorInUserCode(
+        cause, "Error notifying InjectionListener %s of %s.%n Reason: %s", listener, type, cause);
+  }
+
+  /**
+   * Returns {@code value} if it is non-null or allowed to be null. Otherwise a message is added and
+   * an {@code InternalProvisionException} is thrown.
+   */
+  static void onNullInjectedIntoNonNullableDependency(Object source, Dependency<?> dependency)
+      throws InternalProvisionException {
+    // Hack to allow null parameters to @Provides methods, for backwards compatibility.
+    if (dependency.getInjectionPoint().getMember() instanceof Method) {
+      Method annotated = (Method) dependency.getInjectionPoint().getMember();
+      if (annotated.isAnnotationPresent(Provides.class)) {
+        switch (InternalFlags.getNullableProvidesOption()) {
+          case ERROR:
+            break; // break out & let the below exception happen
+          case IGNORE:
+            return; // user doesn't care about injecting nulls to non-@Nullables.
+          case WARN:
+            // Warn only once, otherwise we spam logs too much.
+            if (warnedDependencies.add(dependency)) {
+              logger.log(
+                  Level.WARNING,
+                  "Guice injected null into {0} (a {1}), please mark it @Nullable."
+                      + " Use -Dguice_check_nullable_provides_params=ERROR to turn this into an"
+                      + " error.",
+                  new Object[] {
+                    Messages.formatParameter(dependency), Messages.convert(dependency.getKey())
+                  });
+            }
+            return;
+        }
+      }
+    }
+
+    Object formattedDependency =
+        (dependency.getParameterIndex() != -1)
+            ? Messages.formatParameter(dependency)
+            : StackTraceElements.forMember(dependency.getInjectionPoint().getMember());
+
+    throw InternalProvisionException.create(
+            "null returned by binding at %s%n but %s is not @Nullable", source, formattedDependency)
+        .addSource(source);
+  }
+
+  private final List<Object> sourcesToPrepend = new ArrayList<>();
+  private final ImmutableList<Message> errors;
+
+  private InternalProvisionException(Message error) {
+    this(ImmutableList.of(error));
+  }
+
+  private InternalProvisionException(Iterable<Message> errors) {
+    this.errors = ImmutableList.copyOf(errors);
+    checkArgument(!this.errors.isEmpty(), "Can't create a provision exception with no errors");
+  }
+
+  /**
+   * Prepends the given {@code source} to the stack of binding sources for the errors reported in
+   * this exception.
+   *
+   * <p>See {@link Errors#withSource(Object)}
+   *
+   * <p>It is expected that this method is called as the exception propagates up the stack.
+   *
+   * @param source
+   * @return {@code this}
+   */
+  InternalProvisionException addSource(Object source) {
+    if (source == SourceProvider.UNKNOWN_SOURCE) {
+      return this;
+    }
+    int sz = sourcesToPrepend.size();
+    if (sz > 0 && sourcesToPrepend.get(sz - 1) == source) {
+      // This is for when there are two identical sources added in a row.  This behavior is copied
+      // from Errors.withSource where it can happen when an constructor/provider method throws an
+      // exception
+      return this;
+    }
+    sourcesToPrepend.add(source);
+    return this;
+  }
+
+  ImmutableList<Message> getErrors() {
+    ImmutableList.Builder<Message> builder = ImmutableList.builder();
+    // reverse them since sources are added as the exception propagates (so the first source is the
+    // last one added)
+    List<Object> newSources = Lists.reverse(sourcesToPrepend);
+    for (Message error : errors) {
+      builder.add(Messages.mergeSources(newSources, error));
+    }
+    return builder.build();
+  }
+
+  /** Returns this exception convered to a ProvisionException. */
+  public ProvisionException toProvisionException() {
+    return new ProvisionException(getErrors());
+  }
+}

src/main/java/com/google/inject/internal/LinkedProviderBindingImpl.java

@@ -15,8 +15,9 @@ import java.util.Set;
 final class LinkedProviderBindingImpl<T>
         extends BindingImpl<T> implements ProviderKeyBinding<T>, HasDependencies, DelayedInitialize {
 
-    final Key<? extends javax.inject.Provider<? extends T>> providerKey;
+    private final Key<? extends javax.inject.Provider<? extends T>> providerKey;
-    final DelayedInitialize delayedInitializer;
+
+    private final DelayedInitialize delayedInitializer;
 
     private LinkedProviderBindingImpl(InjectorImpl injector, Key<T> key, Object source,
                                       InternalFactory<? extends T> internalFactory, Scoping scoping,
@@ -27,7 +28,7 @@ final class LinkedProviderBindingImpl<T>
         this.delayedInitializer = delayedInitializer;
     }
 
-    public LinkedProviderBindingImpl(InjectorImpl injector, Key<T> key, Object source,
+    LinkedProviderBindingImpl(InjectorImpl injector, Key<T> key, Object source,
                                      InternalFactory<? extends T> internalFactory, Scoping scoping,
                                      Key<? extends javax.inject.Provider<? extends T>> providerKey) {
         this(injector, key, source, internalFactory, scoping, providerKey, null);
@@ -44,36 +45,43 @@ final class LinkedProviderBindingImpl<T>
                                                                   Object source, InternalFactory<? extends T> internalFactory, Scoping scoping,
                                                                   Key<? extends javax.inject.Provider<? extends T>> providerKey,
                                                                   DelayedInitialize delayedInitializer) {
-        return new LinkedProviderBindingImpl<T>(injector, key, source, internalFactory, scoping,
+        return new LinkedProviderBindingImpl<>(injector, key, source, internalFactory, scoping,
                 providerKey, delayedInitializer);
     }
 
+    @Override
     public <V> V acceptTargetVisitor(BindingTargetVisitor<? super T, V> visitor) {
         return visitor.visit(this);
     }
 
+    @Override
     public Key<? extends javax.inject.Provider<? extends T>> getProviderKey() {
         return providerKey;
     }
 
+    @Override
     public void initialize(InjectorImpl injector, Errors errors) throws ErrorsException {
         if (delayedInitializer != null) {
             delayedInitializer.initialize(injector, errors);
         }
     }
 
+    @Override
     public Set<Dependency<?>> getDependencies() {
-        return ImmutableSet.<Dependency<?>>of(Dependency.get(providerKey));
+        return ImmutableSet.of(Dependency.get(providerKey));
     }
 
+    @Override
     public BindingImpl<T> withScoping(Scoping scoping) {
-        return new LinkedProviderBindingImpl<T>(getSource(), getKey(), scoping, providerKey);
+        return new LinkedProviderBindingImpl<>(getSource(), getKey(), scoping, providerKey);
     }
 
+    @Override
     public BindingImpl<T> withKey(Key<T> key) {
-        return new LinkedProviderBindingImpl<T>(getSource(), key, getScoping(), providerKey);
+        return new LinkedProviderBindingImpl<>(getSource(), key, getScoping(), providerKey);
     }
 
+    @Override
     public void applyTo(Binder binder) {
         getScoping().applyTo(binder.withSource(getSource())
                 .bind(getKey()).toProvider(getProviderKey()));

src/main/java/com/google/inject/internal/MembersInjectorImpl.java

@@ -13,68 +13,68 @@ import com.google.inject.spi.InjectionPoint;
  * Injects members of instances of a given type.
  */
 final class MembersInjectorImpl<T> implements MembersInjector<T> {
-    private final TypeLiteral<T> typeLiteral;
-    private final InjectorImpl injector;
-    private final ImmutableList<SingleMemberInjector> memberInjectors;
-    private final ImmutableSet<MembersInjector<? super T>> userMembersInjectors;
-    private final ImmutableSet<InjectionListener<? super T>> injectionListeners;
 
-    MembersInjectorImpl(InjectorImpl injector, TypeLiteral<T> typeLiteral,
+    private final TypeLiteral<T> typeLiteral;
-                        EncounterImpl<T> encounter, ImmutableList<SingleMemberInjector> memberInjectors) {
+
+    private final InjectorImpl injector;
+
+    private final ImmutableList<SingleMemberInjector> memberInjectors;
+
+    private final ImmutableList<MembersInjector<? super T>> userMembersInjectors;
+
+    private final ImmutableList<InjectionListener<? super T>> injectionListeners;
+
+    MembersInjectorImpl(InjectorImpl injector,
+                        TypeLiteral<T> typeLiteral,
+                        EncounterImpl<T> encounter,
+                        ImmutableList<SingleMemberInjector> memberInjectors) {
         this.injector = injector;
         this.typeLiteral = typeLiteral;
-        this.memberInjectors = memberInjectors;
+        this.memberInjectors = memberInjectors.isEmpty() ? null : memberInjectors;
-        this.userMembersInjectors = encounter.getMembersInjectors();
+        this.userMembersInjectors =
-        this.injectionListeners = encounter.getInjectionListeners();
+                encounter.getMembersInjectors().isEmpty() ? null : encounter.getMembersInjectors().asList();
+        this.injectionListeners =
+                encounter.getInjectionListeners().isEmpty()
+                        ? null
+                        : encounter.getInjectionListeners().asList();
     }
 
     public ImmutableList<SingleMemberInjector> getMemberInjectors() {
-        return memberInjectors;
+        return  memberInjectors == null ? ImmutableList.of() : memberInjectors;
     }
 
     public void injectMembers(T instance) {
-        Errors errors = new Errors(typeLiteral);
+        TypeLiteral<T> localTypeLiteral = typeLiteral;
         try {
-            injectAndNotify(instance, errors, null, null, typeLiteral, false);
+            injectAndNotify(instance, null, null, localTypeLiteral, false);
-        } catch (ErrorsException e) {
+        } catch (InternalProvisionException ipe) {
-            errors.merge(e.getErrors());
+            throw ipe.addSource(localTypeLiteral).toProvisionException();
         }
-
-        errors.throwProvisionExceptionIfErrorsExist();
     }
 
     void injectAndNotify(final T instance,
-                         final Errors errors,
                          final Key<T> key, // possibly null!
                          final ProvisionListenerStackCallback<T> provisionCallback, // possibly null!
                          final Object source,
-                         final boolean toolableOnly) throws ErrorsException {
+                         final boolean toolableOnly) throws InternalProvisionException {
         if (instance == null) {
             return;
         }
-
+        final InternalContext context = injector.enterContext();
-        injector.callInContext(new ContextualCallable<Void>() {
-            @Override
-            public Void call(final InternalContext context) throws ErrorsException {
         context.pushState(key, source);
         try {
             if (provisionCallback != null && provisionCallback.hasListeners()) {
-                        provisionCallback.provision(errors, context, new ProvisionCallback<T>() {
+                provisionCallback.provision(context, () -> {
-                            @Override
+                            injectMembers(instance, context, toolableOnly);
-                            public T call() {
-                                injectMembers(instance, errors, context, toolableOnly);
                             return instance;
-                            }
                         });
             } else {
-                        injectMembers(instance, errors, context, toolableOnly);
+                injectMembers(instance, context, toolableOnly);
             }
         } finally {
             context.popState();
+            context.close();
         }
-                return null;
-            }
-        });
 
         // TODO: We *could* notify listeners too here,
         // but it's not clear if we want to.  There's no way to know
@@ -85,38 +85,54 @@ final class MembersInjectorImpl<T> implements MembersInjector<T> {
         // the above callInContext could return 'true' if it injected
         // anything.)
         if (!toolableOnly) {
-            notifyListeners(instance, errors);
+            notifyListeners(instance);
         }
     }
 
-    void notifyListeners(T instance, Errors errors) throws ErrorsException {
+    void notifyListeners(T instance) throws InternalProvisionException {
-        int numErrorsBefore = errors.size();
+        ImmutableList<InjectionListener<? super T>> localInjectionListeners = injectionListeners;
-        for (InjectionListener<? super T> injectionListener : injectionListeners) {
+        if (localInjectionListeners == null) {
+            // no listeners
+            return;
+        }
+        // optimization: use manual for/each to save allocating an iterator here
+        for (int i = 0; i < localInjectionListeners.size(); i++) {
+            InjectionListener<? super T> injectionListener = localInjectionListeners.get(i);
             try {
                 injectionListener.afterInjection(instance);
             } catch (RuntimeException e) {
-                errors.errorNotifyingInjectionListener(injectionListener, typeLiteral, e);
+                throw InternalProvisionException.errorNotifyingInjectionListener(
+                        injectionListener, typeLiteral, e);
             }
         }
-        errors.throwIfNewErrors(numErrorsBefore);
     }
 
-    void injectMembers(T t, Errors errors, InternalContext context, boolean toolableOnly) {
+    void injectMembers(T t,  InternalContext context, boolean toolableOnly)
+            throws InternalProvisionException {
+        ImmutableList<SingleMemberInjector> localMembersInjectors = memberInjectors;
+        if (localMembersInjectors != null) {
             // optimization: use manual for/each to save allocating an iterator here
-        for (int i = 0, size = memberInjectors.size(); i < size; i++) {
+            for (int i = 0, size = localMembersInjectors.size(); i < size; i++) {
-            SingleMemberInjector injector = memberInjectors.get(i);
+                SingleMemberInjector injector = localMembersInjectors.get(i);
                 if (!toolableOnly || injector.getInjectionPoint().isToolable()) {
-                injector.inject(errors, context, t);
+                    injector.inject(context, t);
+                }
             }
         }
 
         // TODO: There's no way to know if a user's MembersInjector wants toolable injections.
         if (!toolableOnly) {
-            for (MembersInjector<? super T> userMembersInjector : userMembersInjectors) {
+            ImmutableList<MembersInjector<? super T>> localUsersMembersInjectors = userMembersInjectors;
+            if (localUsersMembersInjectors != null) {
+                // optimization: use manual for/each to save allocating an iterator here
+                for (int i = 0; i < localUsersMembersInjectors.size(); i++) {
+                    MembersInjector<? super T> userMembersInjector = localUsersMembersInjectors.get(i);
                     try {
                         userMembersInjector.injectMembers(t);
                     } catch (RuntimeException e) {
-                    errors.errorInUserInjector(userMembersInjector, typeLiteral, e);
+                        throw InternalProvisionException.errorInUserInjector(
+                                userMembersInjector, typeLiteral, e);
+                    }
                 }
             }
         }
@@ -128,11 +144,15 @@ final class MembersInjectorImpl<T> implements MembersInjector<T> {
     }
 
     public ImmutableSet<InjectionPoint> getInjectionPoints() {
+        ImmutableList<SingleMemberInjector> localMemberInjectors = memberInjectors;
+        if (localMemberInjectors != null) {
             ImmutableSet.Builder<InjectionPoint> builder = ImmutableSet.builder();
-        for (SingleMemberInjector memberInjector : memberInjectors) {
+            for (SingleMemberInjector memberInjector : localMemberInjectors) {
                 builder.add(memberInjector.getInjectionPoint());
             }
             return builder.build();
         }
+        return ImmutableSet.of();
+    }
 
 }

src/main/java/com/google/inject/internal/MembersInjectorStore.java

@@ -1,6 +1,9 @@
 package com.google.inject.internal;
 
+import static com.google.common.collect.ImmutableListMultimap.flatteningToImmutableListMultimap;
+
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 import com.google.inject.ConfigurationException;
@@ -11,24 +14,25 @@ import com.google.inject.spi.TypeListenerBinding;
 
 import java.lang.reflect.Field;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 /**
  * Members injectors by type.
  */
 final class MembersInjectorStore {
+
     private final InjectorImpl injector;
+
     private final ImmutableList<TypeListenerBinding> typeListenerBindings;
 
-    private final FailableCache<TypeLiteral<?>, MembersInjectorImpl<?>> cache
+    private final FailableCache<TypeLiteral<?>, MembersInjectorImpl<?>> cache = new FailableCache<>() {
-            = new FailableCache<TypeLiteral<?>, MembersInjectorImpl<?>>() {
                 @Override
                 protected MembersInjectorImpl<?> create(TypeLiteral<?> type, Errors errors)
                         throws ErrorsException {
                     return createWithListeners(type, errors);
                 }
             };
-
     MembersInjectorStore(InjectorImpl injector,
                          List<TypeListenerBinding> typeListenerBindings) {
         this.injector = injector;
@@ -39,7 +43,7 @@ final class MembersInjectorStore {
      * Returns true if any type listeners are installed. Other code may take shortcuts when there
      * aren't any type listeners.
      */
-    public boolean hasTypeListeners() {
+    boolean hasTypeListeners() {
         return !typeListenerBindings.isEmpty();
     }
 
@@ -81,7 +85,7 @@ final class MembersInjectorStore {
         ImmutableList<SingleMemberInjector> injectors = getInjectors(injectionPoints, errors);
         errors.throwIfNewErrors(numErrorsBefore);
 
-        EncounterImpl<T> encounter = new EncounterImpl<T>(errors, injector.lookups);
+        EncounterImpl<T> encounter = new EncounterImpl<>(errors, injector.lookups);
         Set<TypeListener> alreadySeenListeners = Sets.newHashSet();
         for (TypeListenerBinding binding : typeListenerBindings) {
             TypeListener typeListener = binding.getListener();
@@ -97,7 +101,7 @@ final class MembersInjectorStore {
         encounter.invalidate();
         errors.throwIfNewErrors(numErrorsBefore);
 
-        return new MembersInjectorImpl<T>(injector, type, encounter, injectors);
+        return new MembersInjectorImpl<>(injector, type, encounter, injectors);
     }
 
     /**
@@ -121,4 +125,11 @@ final class MembersInjectorStore {
         }
         return ImmutableList.copyOf(injectors);
     }
+
+    ImmutableListMultimap<TypeLiteral<?>, InjectionPoint> getAllInjectionPoints() {
+        return cache.asMap().entrySet().stream()
+                .collect(
+                        flatteningToImmutableListMultimap(
+                                Map.Entry::getKey, entry -> entry.getValue().getInjectionPoints().stream()));
+    }
 }

src/main/java/com/google/inject/internal/MessageProcessor.java

@@ -12,20 +12,8 @@ final class MessageProcessor extends AbstractProcessor {
         super(errors);
     }
 
-    public static String getRootMessage(Throwable t) {
-        Throwable cause = t.getCause();
-        return cause == null ? t.toString() : getRootMessage(cause);
-    }
-
     @Override
     public Boolean visit(Message message) {
-        if (message.getCause() != null) {
-            String rootMessage = getRootMessage(message.getCause());
-            /*logger.log(Level.INFO,
-                    "An exception was caught and reported. Message: " + rootMessage,
-                    message.getCause());*/
-        }
-
         errors.addMessage(message);
         return true;
     }

src/main/java/com/google/inject/internal/Messages.java

@@ -0,0 +1,391 @@
+package com.google.inject.internal;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import com.google.common.base.Equivalence;
+import com.google.common.base.Objects;
+import com.google.common.base.Throwables;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import com.google.inject.Key;
+import com.google.inject.TypeLiteral;
+import com.google.inject.internal.util.Classes;
+import com.google.inject.internal.util.StackTraceElements;
+import com.google.inject.spi.Dependency;
+import com.google.inject.spi.ElementSource;
+import com.google.inject.spi.InjectionPoint;
+import com.google.inject.spi.Message;
+import java.lang.reflect.Field;
+import java.lang.reflect.Member;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Formatter;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Utility methods for {@link Message} objects
+ */
+public final class Messages {
+
+    private Messages() {
+    }
+
+    /**
+     * Prepends the list of sources to the given {@link Message}
+     */
+    static Message mergeSources(List<Object> sources, Message message) {
+        List<Object> messageSources = message.getSources();
+        // It is possible that the end of getSources() and the beginning of message.getSources() are
+        // equivalent, in this case we should drop the repeated source when joining the lists.  The
+        // most likely scenario where this would happen is when a scoped binding throws an exception,
+        // due to the fact that InternalFactoryToProviderAdapter applies the binding source when
+        // merging errors.
+        if (!sources.isEmpty() && !messageSources.isEmpty() &&
+                Objects.equal(messageSources.get(0), sources.get(sources.size() - 1))) {
+            messageSources = messageSources.subList(1, messageSources.size());
+        }
+        return new Message(ImmutableList.builder().addAll(sources).addAll(messageSources).build(),
+                message.getMessage(), message.getCause());
+    }
+
+    /**
+     * Calls {@link String#format} after converting the arguments using some standard guice formatting
+     * for {@link Key}, {@link Class} and {@link Member} objects.
+     */
+    public static String format(String messageFormat, Object... arguments) {
+        for (int i = 0; i < arguments.length; i++) {
+            arguments[i] = convert(arguments[i]);
+        }
+        return String.format(messageFormat, arguments);
+    }
+
+    /**
+     * Returns the formatted message for an exception with the specified messages.
+     */
+    public static String formatMessages(String heading, Collection<Message> errorMessages) {
+        Formatter fmt = new Formatter().format(heading).format(":%n%n");
+        int index = 1;
+        boolean displayCauses = getOnlyCause(errorMessages) == null;
+
+        Map<Equivalence.Wrapper<Throwable>, Integer> causes = Maps.newHashMap();
+        for (Message errorMessage : errorMessages) {
+            int thisIdx = index++;
+            fmt.format("%s) %s%n", thisIdx, errorMessage.getMessage());
+
+            List<Object> dependencies = errorMessage.getSources();
+            for (int i = dependencies.size() - 1; i >= 0; i--) {
+                Object source = dependencies.get(i);
+                formatSource(fmt, source);
+            }
+
+            Throwable cause = errorMessage.getCause();
+            if (displayCauses && cause != null) {
+                Equivalence.Wrapper<Throwable> causeEquivalence = ThrowableEquivalence.INSTANCE.wrap(cause);
+                if (!causes.containsKey(causeEquivalence)) {
+                    causes.put(causeEquivalence, thisIdx);
+                    fmt.format("Caused by: %s", Throwables.getStackTraceAsString(cause));
+                } else {
+                    int causeIdx = causes.get(causeEquivalence);
+                    fmt.format(
+                            "Caused by: %s (same stack trace as error #%s)",
+                            cause.getClass().getName(), causeIdx);
+                }
+            }
+
+            fmt.format("%n");
+        }
+
+        if (errorMessages.size() == 1) {
+            fmt.format("1 error");
+        } else {
+            fmt.format("%s errors", errorMessages.size());
+        }
+
+        return fmt.toString();
+    }
+
+    /**
+     * Creates a new Message without a cause.
+     *
+     * @param messageFormat Format string
+     * @param arguments     format string arguments
+     */
+    public static Message create(String messageFormat, Object... arguments) {
+        return create(null, messageFormat, arguments);
+    }
+
+    /**
+     * Creates a new Message with the given cause.
+     *
+     * @param cause         The exception that caused the error
+     * @param messageFormat Format string
+     * @param arguments     format string arguments
+     */
+    public static Message create(Throwable cause, String messageFormat, Object... arguments) {
+        return create(cause, ImmutableList.of(), messageFormat, arguments);
+    }
+
+    /**
+     * Creates a new Message with the given cause and a binding source stack.
+     *
+     * @param cause         The exception that caused the error
+     * @param sources       The binding sources for the source stack
+     * @param messageFormat Format string
+     * @param arguments     format string arguments
+     */
+    public static Message create(Throwable cause, List<Object> sources, String messageFormat, Object... arguments) {
+        String message = format(messageFormat, arguments);
+        return new Message(sources, message, cause);
+    }
+
+    /**
+     * Formats an object in a user friendly way.
+     */
+    public static Object convert(Object o) {
+        ElementSource source = null;
+        if (o instanceof ElementSource) {
+            source = (ElementSource) o;
+            o = source.getDeclaringSource();
+        }
+        return convert(o, source);
+    }
+
+    public static Object convert(Object o, ElementSource source) {
+        for (Converter<?> converter : converters) {
+            if (converter.appliesTo(o)) {
+                return appendModules(converter.convert(o), source);
+            }
+        }
+        return appendModules(o, source);
+    }
+
+    private static Object appendModules(Object source, ElementSource elementSource) {
+        String modules = moduleSourceString(elementSource);
+        if (modules.length() == 0) {
+            return source;
+        } else {
+            return source + modules;
+        }
+    }
+
+    private static String moduleSourceString(ElementSource elementSource) {
+        // if we only have one module (or don't know what they are), then don't bother
+        // reporting it, because the source already is going to report exactly that module.
+        if (elementSource == null) {
+            return "";
+        }
+        List<String> modules = Lists.newArrayList(elementSource.getModuleClassNames());
+        // Insert any original element sources w/ module info into the path.
+        while (elementSource.getOriginalElementSource() != null) {
+            elementSource = elementSource.getOriginalElementSource();
+            modules.addAll(0, elementSource.getModuleClassNames());
+        }
+        if (modules.size() <= 1) {
+            return "";
+        }
+
+        // Ideally we'd do:
+        //    return Joiner.on(" -> ")
+        //        .appendTo(new StringBuilder(" (via modules: "), Lists.reverse(modules))
+        //        .append(")").toString();
+        // ... but for some reason we can't find Lists.reverse, so do it the boring way.
+        StringBuilder builder = new StringBuilder(" (via modules: ");
+        for (int i = modules.size() - 1; i >= 0; i--) {
+            builder.append(modules.get(i));
+            if (i != 0) {
+                builder.append(" -> ");
+            }
+        }
+        builder.append(")");
+        return builder.toString();
+    }
+
+    static void formatSource(Formatter formatter, Object source) {
+        ElementSource elementSource = null;
+        if (source instanceof ElementSource) {
+            elementSource = (ElementSource) source;
+            source = elementSource.getDeclaringSource();
+        }
+        formatSource(formatter, source, elementSource);
+    }
+
+    static void formatSource(Formatter formatter, Object source, ElementSource elementSource) {
+        String modules = moduleSourceString(elementSource);
+        if (source instanceof Dependency) {
+            Dependency<?> dependency = (Dependency<?>) source;
+            InjectionPoint injectionPoint = dependency.getInjectionPoint();
+            if (injectionPoint != null) {
+                formatInjectionPoint(formatter, dependency, injectionPoint, elementSource);
+            } else {
+                formatSource(formatter, dependency.getKey(), elementSource);
+            }
+
+        } else if (source instanceof InjectionPoint) {
+            formatInjectionPoint(formatter, null, (InjectionPoint) source, elementSource);
+
+        } else if (source instanceof Class) {
+            formatter.format("  at %s%s%n", StackTraceElements.forType((Class<?>) source), modules);
+
+        } else if (source instanceof Member) {
+            formatter.format("  at %s%s%n", StackTraceElements.forMember((Member) source), modules);
+
+        } else if (source instanceof TypeLiteral) {
+            formatter.format("  while locating %s%s%n", source, modules);
+
+        } else if (source instanceof Key) {
+            Key<?> key = (Key<?>) source;
+            formatter.format("  while locating %s%n", convert(key, elementSource));
+
+        } else if (source instanceof Thread) {
+            formatter.format("  in thread %s%n", source);
+
+        } else {
+            formatter.format("  at %s%s%n", source, modules);
+        }
+    }
+
+    private static void formatInjectionPoint(
+            Formatter formatter,
+            Dependency<?> dependency,
+            InjectionPoint injectionPoint,
+            ElementSource elementSource) {
+        Member member = injectionPoint.getMember();
+        Class<? extends Member> memberType = Classes.memberType(member);
+
+        if (memberType == Field.class) {
+            dependency = injectionPoint.getDependencies().get(0);
+            formatter.format("  while locating %s%n", convert(dependency.getKey(), elementSource));
+            formatter.format("    for field at %s%n", StackTraceElements.forMember(member));
+
+        } else if (dependency != null) {
+            formatter.format("  while locating %s%n", convert(dependency.getKey(), elementSource));
+            formatter.format("    for %s%n", formatParameter(dependency));
+
+        } else {
+            formatSource(formatter, injectionPoint.getMember());
+        }
+    }
+
+    static String formatParameter(Dependency<?> dependency) {
+        int ordinal = dependency.getParameterIndex() + 1;
+        return String.format(
+                "the %s%s parameter of %s",
+                ordinal,
+                getOrdinalSuffix(ordinal),
+                StackTraceElements.forMember(dependency.getInjectionPoint().getMember()));
+    }
+
+    /**
+     * Maps {@code 1} to the string {@code "1st"} ditto for all non-negative numbers
+     *
+     * @see <a href="https://en.wikipedia.org/wiki/English_numerals#Ordinal_numbers">
+     * https://en.wikipedia.org/wiki/English_numerals#Ordinal_numbers</a>
+     */
+    private static String getOrdinalSuffix(int ordinal) {
+        // negative ordinals don't make sense, we allow zero though because we are programmers
+        checkArgument(ordinal >= 0);
+        if ((ordinal / 10) % 10 == 1) {
+            // all the 'teens' are weird
+            return "th";
+        } else {
+            // could use a lookup table? any better?
+            switch (ordinal % 10) {
+                case 1:
+                    return "st";
+                case 2:
+                    return "nd";
+                case 3:
+                    return "rd";
+                default:
+                    return "th";
+            }
+        }
+    }
+
+    private abstract static class Converter<T> {
+
+        final Class<T> type;
+
+        Converter(Class<T> type) {
+            this.type = type;
+        }
+
+        boolean appliesTo(Object o) {
+            return o != null && type.isAssignableFrom(o.getClass());
+        }
+
+        String convert(Object o) {
+            return toString(type.cast(o));
+        }
+
+        abstract String toString(T t);
+    }
+
+    @SuppressWarnings({"rawtypes"}) // rawtypes aren't avoidable
+    private static final Collection<Converter<?>> converters =
+            ImmutableList.of(
+                    new Converter<>(Class.class) {
+                        @Override
+                        public String toString(Class c) {
+                            return c.getName();
+                        }
+                    },
+                    new Converter<>(Member.class) {
+                        @Override
+                        public String toString(Member member) {
+                            return Classes.toString(member);
+                        }
+                    },
+                    new Converter<>(Key.class) {
+                        @Override
+                        public String toString(Key key) {
+                            if (key.getAnnotationType() != null) {
+                                return key.getTypeLiteral()
+                                        + " annotated with "
+                                        + (key.getAnnotation() != null ? key.getAnnotation() : key.getAnnotationType());
+                            } else {
+                                return key.getTypeLiteral().toString();
+                            }
+                        }
+                    });
+
+    /**
+     * Returns the cause throwable if there is exactly one cause in {@code messages}. If there are
+     * zero or multiple messages with causes, null is returned.
+     */
+    public static Throwable getOnlyCause(Collection<Message> messages) {
+        Throwable onlyCause = null;
+        for (Message message : messages) {
+            Throwable messageCause = message.getCause();
+            if (messageCause == null) {
+                continue;
+            }
+
+            if (onlyCause != null && !ThrowableEquivalence.INSTANCE.equivalent(onlyCause, messageCause)) {
+                return null;
+            }
+
+            onlyCause = messageCause;
+        }
+
+        return onlyCause;
+    }
+
+    private static final class ThrowableEquivalence extends Equivalence<Throwable> {
+        static final ThrowableEquivalence INSTANCE = new ThrowableEquivalence();
+
+        @Override
+        protected boolean doEquivalent(Throwable a, Throwable b) {
+            return a.getClass().equals(b.getClass())
+                    && Objects.equal(a.getMessage(), b.getMessage())
+                    && Arrays.equals(a.getStackTrace(), b.getStackTrace())
+                    && equivalent(a.getCause(), b.getCause());
+        }
+
+        @Override
+        protected int doHash(Throwable t) {
+            return Objects.hashCode(t.getClass().hashCode(), t.getMessage(), hash(t.getCause()));
+        }
+    }
+}

src/main/java/com/google/inject/internal/MoreTypes.java

@@ -264,7 +264,7 @@ public class MoreTypes {
 
         // we skip searching through interfaces if unknown is an interface
         if (toResolve.isInterface()) {
-            Class[] interfaces = rawType.getInterfaces();
+            Class<?>[] interfaces = rawType.getInterfaces();
             for (int i = 0, length = interfaces.length; i < length; i++) {
                 if (interfaces[i] == toResolve) {
                     return rawType.getGenericInterfaces()[i];
@@ -291,7 +291,7 @@ public class MoreTypes {
         return toResolve;
     }
 
-    public static Type resolveTypeVariable(Type type, Class<?> rawType, TypeVariable unknown) {
+    public static Type resolveTypeVariable(Type type, Class<?> rawType, TypeVariable<?> unknown) {
         Class<?> declaredByRaw = declaringClassOf(unknown);
 
         // we can't reduce this further
@@ -321,7 +321,7 @@ public class MoreTypes {
      * Returns the declaring class of {@code typeVariable}, or {@code null} if it was not declared by
      * a class.
      */
-    private static Class<?> declaringClassOf(TypeVariable typeVariable) {
+    private static Class<?> declaringClassOf(TypeVariable<?> typeVariable) {
         GenericDeclaration genericDeclaration = typeVariable.getGenericDeclaration();
         return genericDeclaration instanceof Class
                 ? (Class<?>) genericDeclaration
@@ -365,7 +365,7 @@ public class MoreTypes {
 
         private static void ensureOwnerType(Type ownerType, Type rawType) {
             if (rawType instanceof Class<?>) {
-                Class rawTypeAsClass = (Class) rawType;
+                Class<?> rawTypeAsClass = (Class) rawType;
                 checkArgument(ownerType != null || rawTypeAsClass.getEnclosingClass() == null,
                         "No owner type for enclosed %s", rawType);
                 checkArgument(ownerType == null || rawTypeAsClass.getEnclosingClass() != null,
@@ -373,18 +373,22 @@ public class MoreTypes {
             }
         }
 
+        @Override
         public Type[] getActualTypeArguments() {
             return typeArguments.clone();
         }
 
+        @Override
         public Type getRawType() {
             return rawType;
         }
 
+        @Override
         public Type getOwnerType() {
             return ownerType;
         }
 
+        @Override
         public boolean isFullySpecified() {
             if (ownerType != null && !MoreTypes.isFullySpecified(ownerType)) {
                 return false;
@@ -441,10 +445,12 @@ public class MoreTypes {
             this.componentType = canonicalize(componentType);
         }
 
+        @Override
         public Type getGenericComponentType() {
             return componentType;
         }
 
+        @Override
         public boolean isFullySpecified() {
             return MoreTypes.isFullySpecified(componentType);
         }
@@ -495,14 +501,17 @@ public class MoreTypes {
             }
         }
 
+        @Override
         public Type[] getUpperBounds() {
             return new Type[]{upperBound};
         }
 
+        @Override
         public Type[] getLowerBounds() {
             return lowerBound != null ? new Type[]{lowerBound} : EMPTY_TYPE_ARRAY;
         }
 
+        @Override
         public boolean isFullySpecified() {
             return MoreTypes.isFullySpecified(upperBound)
                     && (lowerBound == null || MoreTypes.isFullySpecified(lowerBound));

src/main/java/com/google/inject/internal/PrivateElementProcessor.java

@@ -25,7 +25,7 @@ final class PrivateElementProcessor extends AbstractProcessor {
         return true;
     }
 
-    public List<InjectorShell.Builder> getInjectorShellBuilders() {
+    List<InjectorShell.Builder> getInjectorShellBuilders() {
         return injectorShellBuilders;
     }
 }

src/main/java/com/google/inject/internal/PrivateElementsImpl.java

@@ -49,10 +49,12 @@ public final class PrivateElementsImpl implements PrivateElements {
         this.source = checkNotNull(source, "source");
     }
 
+    @Override
     public Object getSource() {
         return source;
     }
 
+    @Override
     public List<Element> getElements() {
         if (elements == null) {
             elements = ImmutableList.copyOf(elementsMutable);
@@ -62,15 +64,17 @@ public final class PrivateElementsImpl implements PrivateElements {
         return elements;
     }
 
+    @Override
     public Injector getInjector() {
         return injector;
     }
 
-    public void initInjector(Injector injector) {
+    void initInjector(Injector injector) {
         checkState(this.injector == null, "injector already initialized");
         this.injector = checkNotNull(injector, "injector");
     }
 
+    @Override
     public Set<Key<?>> getExposedKeys() {
         if (exposedKeysToSources == null) {
             Map<Key<?>, Object> exposedKeysToSourcesMutable = Maps.newLinkedHashMap();
@@ -84,6 +88,7 @@ public final class PrivateElementsImpl implements PrivateElements {
         return exposedKeysToSources.keySet();
     }
 
+    @Override
     public <T> T acceptVisitor(ElementVisitor<T> visitor) {
         return visitor.visit(this);
     }
@@ -96,6 +101,7 @@ public final class PrivateElementsImpl implements PrivateElements {
         exposureBuilders.add(exposureBuilder);
     }
 
+    @Override
     public void applyTo(Binder binder) {
         PrivateBinder privateBinder = binder.withSource(source).newPrivateBinder();
 
@@ -109,6 +115,7 @@ public final class PrivateElementsImpl implements PrivateElements {
         }
     }
 
+    @Override
     public Object getExposedSource(Key<?> key) {
         getExposedKeys(); // ensure exposedKeysToSources is populated
         Object source = exposedKeysToSources.get(key);

src/main/java/com/google/inject/internal/ProcessedBindingData.java

@@ -11,8 +11,11 @@ import java.util.List;
 class ProcessedBindingData {
 
     private final List<CreationListener> creationListeners = Lists.newArrayList();
+
     private final List<Runnable> uninitializedBindings = Lists.newArrayList();
 
+    private final List<Runnable> delayedUninitializedBindings = Lists.newArrayList();
+
     void addCreationListener(CreationListener listener) {
         creationListeners.add(listener);
     }
@@ -21,6 +24,10 @@ class ProcessedBindingData {
         uninitializedBindings.add(runnable);
     }
 
+    void addDelayedUninitializedBinding(Runnable runnable) {
+        delayedUninitializedBindings.add(runnable);
+    }
+
     void initializeBindings() {
         for (Runnable initializer : uninitializedBindings) {
             initializer.run();
@@ -33,4 +40,14 @@ class ProcessedBindingData {
         }
     }
 
+    /**
+     * Initialized bindings that need to be delayed until after all injection points and other
+     * bindings are processed. The main current usecase for this is resolving Optional dependencies
+     * for OptionalBinder bindings.
+     */
+    void initializeDelayedBindings() {
+        for (Runnable initializer : delayedUninitializedBindings) {
+            initializer.run();
+        }
+    }
 }

src/main/java/com/google/inject/internal/ProvidedByInternalFactory.java

@@ -2,11 +2,9 @@ package com.google.inject.internal;
 
 import com.google.inject.Key;
 import com.google.inject.ProvidedBy;
-import com.google.inject.Provider;
 import com.google.inject.internal.InjectorImpl.JitLimitation;
 import com.google.inject.spi.Dependency;
-
+import javax.inject.Provider;
-import static com.google.common.base.Preconditions.checkState;
 
 /**
  * An {@link InternalFactory} for {@literal @}{@link ProvidedBy} bindings.
@@ -34,40 +32,48 @@ class ProvidedByInternalFactory<T> extends ProviderInternalFactory<T>
         provisionCallback = listener;
     }
 
+    @Override
     public void initialize(InjectorImpl injector, Errors errors) throws ErrorsException {
         providerBinding =
                 injector.getBindingOrThrow(providerKey, errors, JitLimitation.NEW_OR_EXISTING_JIT);
     }
 
-    public T get(Errors errors, InternalContext context, Dependency dependency, boolean linked)
+    @Override
-            throws ErrorsException {
+    public T get(InternalContext context, Dependency<?> dependency, boolean linked)
-        checkState(providerBinding != null, "not initialized");
+            throws InternalProvisionException {
+        BindingImpl<? extends Provider<T>> localProviderBinding = providerBinding;
+        if (localProviderBinding == null) {
+            throw new IllegalStateException("not initialized");
+        }
+        Key<? extends Provider<T>> localProviderKey = providerKey;
+        context.pushState(localProviderKey, localProviderBinding.getSource());
 
-        context.pushState(providerKey, providerBinding.getSource());
         try {
-            errors = errors.withSource(providerKey);
+            Provider<? extends T> provider =
-            Provider<? extends T> provider = providerBinding.getInternalFactory().get(
+                    localProviderBinding.getInternalFactory().get(context, dependency, true);
-                    errors, context, dependency, true);
+            return circularGet(provider, context, dependency, provisionCallback);
-            return circularGet(provider, errors, context, dependency, provisionCallback);
+        } catch (InternalProvisionException ipe) {
+            throw ipe.addSource(localProviderKey);
         } finally {
             context.popState();
         }
     }
 
     @Override
-    protected T provision(javax.inject.Provider<? extends T> provider, Errors errors,
+    protected T provision(javax.inject.Provider<? extends T> provider,
-                          Dependency<?> dependency, ConstructionContext<T> constructionContext)
+                          Dependency<?> dependency,
-            throws ErrorsException {
+                          ConstructionContext<T> constructionContext)
+            throws InternalProvisionException {
         try {
-            Object o = super.provision(provider, errors, dependency, constructionContext);
+            Object o = super.provision(provider, dependency, constructionContext);
             if (o != null && !rawType.isInstance(o)) {
-                throw errors.subtypeNotProvided(providerType, rawType).toException();
+                throw InternalProvisionException.subtypeNotProvided(providerType, rawType);
             }
             @SuppressWarnings("unchecked") // protected by isInstance() check above
             T t = (T) o;
             return t;
         } catch (RuntimeException e) {
-            throw errors.errorInProvider(e).toException();
+            throw InternalProvisionException.errorInProvider(e).addSource(source);
         }
     }
 }

src/main/java/com/google/inject/internal/ProviderInstanceBindingImpl.java

@@ -14,13 +14,13 @@ import com.google.inject.spi.ProviderWithExtensionVisitor;
 
 import java.util.Set;
 
-final class ProviderInstanceBindingImpl<T> extends BindingImpl<T>
+class ProviderInstanceBindingImpl<T> extends BindingImpl<T> implements ProviderInstanceBinding<T> {
-        implements ProviderInstanceBinding<T> {
 
-    final javax.inject.Provider<? extends T> providerInstance;
+    private final javax.inject.Provider<? extends T> providerInstance;
-    final ImmutableSet<InjectionPoint> injectionPoints;
 
-    public ProviderInstanceBindingImpl(InjectorImpl injector, Key<T> key,
+    private final ImmutableSet<InjectionPoint> injectionPoints;
+
+    ProviderInstanceBindingImpl(InjectorImpl injector, Key<T> key,
                                        Object source, InternalFactory<? extends T> internalFactory, Scoping scoping,
                                        javax.inject.Provider<? extends T> providerInstance,
                                        Set<InjectionPoint> injectionPoints) {
@@ -29,7 +29,7 @@ final class ProviderInstanceBindingImpl<T> extends BindingImpl<T>
         this.injectionPoints = ImmutableSet.copyOf(injectionPoints);
     }
 
-    public ProviderInstanceBindingImpl(Object source, Key<T> key, Scoping scoping,
+    ProviderInstanceBindingImpl(Object source, Key<T> key, Scoping scoping,
                                        Set<InjectionPoint> injectionPoints, javax.inject.Provider<? extends T> providerInstance) {
         super(source, key, scoping);
         this.injectionPoints = ImmutableSet.copyOf(injectionPoints);
@@ -61,13 +61,11 @@ final class ProviderInstanceBindingImpl<T> extends BindingImpl<T>
     }
 
     public BindingImpl<T> withScoping(Scoping scoping) {
-        return new ProviderInstanceBindingImpl<T>(
+        return new ProviderInstanceBindingImpl<>(getSource(), getKey(), scoping, injectionPoints, providerInstance);
-                getSource(), getKey(), scoping, injectionPoints, providerInstance);
     }
 
     public BindingImpl<T> withKey(Key<T> key) {
-        return new ProviderInstanceBindingImpl<T>(
+        return new ProviderInstanceBindingImpl<>(getSource(), key, getScoping(), injectionPoints, providerInstance);
-                getSource(), key, getScoping(), injectionPoints, providerInstance);
     }
 
     public void applyTo(Binder binder) {

src/main/java/com/google/inject/internal/ProviderInternalFactory.java

@@ -1,6 +1,5 @@
 package com.google.inject.internal;
 
-import com.google.inject.internal.ProvisionListenerStackCallback.ProvisionCallback;
 import com.google.inject.spi.Dependency;
 
 import javax.inject.Provider;
@@ -20,33 +19,28 @@ abstract class ProviderInternalFactory<T> implements InternalFactory<T> {
         this.source = checkNotNull(source, "source");
     }
 
-    protected T circularGet(final Provider<? extends T> provider, final Errors errors,
+    protected T circularGet(final Provider<? extends T> provider,
-                            InternalContext context, final Dependency<?> dependency,
+                            InternalContext context,
+                            final Dependency<?> dependency,
                             ProvisionListenerStackCallback<T> provisionCallback)
-            throws ErrorsException {
+            throws InternalProvisionException {
         final ConstructionContext<T> constructionContext = context.getConstructionContext(this);
-
         // We have a circular reference between constructors. Return a proxy.
         if (constructionContext.isConstructing()) {
             Class<?> expectedType = dependency.getKey().getTypeLiteral().getRawType();
             // TODO: if we can't proxy this object, can we proxy the other object?
             @SuppressWarnings("unchecked")
-            T proxyType = (T) constructionContext.createProxy(
+            T proxyType = (T) constructionContext.createProxy(context.getInjectorOptions(), expectedType);
-                    errors, context.getInjectorOptions(), expectedType);
             return proxyType;
         }
-
         // Optimization: Don't go through the callback stack if no one's listening.
         constructionContext.startConstruction();
         try {
             if (!provisionCallback.hasListeners()) {
-                return provision(provider, errors, dependency, constructionContext);
+                return provision(provider, dependency, constructionContext);
             } else {
-                return provisionCallback.provision(errors, context, new ProvisionCallback<T>() {
+                return provisionCallback.provision(context, () ->
-                    public T call() throws ErrorsException {
+                        provision(provider, dependency, constructionContext));
-                        return provision(provider, errors, dependency, constructionContext);
-                    }
-                });
             }
         } finally {
             constructionContext.removeCurrentReference();
@@ -58,9 +52,12 @@ abstract class ProviderInternalFactory<T> implements InternalFactory<T> {
      * Provisions a new instance. Subclasses should override this to catch
      * exceptions & rethrow as ErrorsExceptions.
      */
-    protected T provision(Provider<? extends T> provider, Errors errors, Dependency<?> dependency,
+    protected T provision(Provider<? extends T> provider, Dependency<?> dependency,
-                          ConstructionContext<T> constructionContext) throws ErrorsException {
+                          ConstructionContext<T> constructionContext) throws InternalProvisionException {
-        T t = errors.checkForNull(provider.get(), source, dependency);
+        T t = provider.get();
+        if (t == null && !dependency.isNullable()) {
+            InternalProvisionException.onNullInjectedIntoNonNullableDependency(source, dependency);
+        }
         constructionContext.setProxyDelegates(t);
         return t;
     }

src/main/java/com/google/inject/internal/ProviderMethod.java

@@ -6,7 +6,6 @@ import com.google.inject.Binder;
 import com.google.inject.Exposed;
 import com.google.inject.Key;
 import com.google.inject.PrivateBinder;
-import com.google.inject.Provider;
 import com.google.inject.Provides;
 import com.google.inject.internal.util.StackTraceElements;
 import com.google.inject.spi.BindingTargetVisitor;
@@ -21,36 +20,50 @@ import java.lang.annotation.Annotation;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
-import java.util.List;
 import java.util.Set;
 
 /**
  * A provider that invokes a method and returns its result.
  *
  */
-public abstract class ProviderMethod<T> implements ProviderWithExtensionVisitor<T>, HasDependencies,
+public abstract class ProviderMethod<T>
-        ProvidesMethodBinding<T> {
+        extends InternalProviderInstanceBindingImpl.CyclicFactory<T>
+        implements HasDependencies, ProviderWithExtensionVisitor<T>, ProvidesMethodBinding<T> {
 
     protected final Object instance;
+
     protected final Method method;
+
     private final Key<T> key;
+
     private final Class<? extends Annotation> scopeAnnotation;
+
     private final ImmutableSet<Dependency<?>> dependencies;
-    private final List<Provider<?>> parameterProviders;
+
     private final boolean exposed;
+
     private final Annotation annotation;
+
+    /**
+     * Set by {@link #initialize(InjectorImpl, Errors)} so it is always available prior to injection.
+     */
+    private SingleParameterInjector<?>[] parameterInjectors;
+
     /**
      * @param method the method to invoke. It's return type must be the same type as {@code key}.
      */
-    private ProviderMethod(Key<T> key, Method method, Object instance,
+    private ProviderMethod(Key<T> key,
-                           ImmutableSet<Dependency<?>> dependencies, List<Provider<?>> parameterProviders,
+                           Method method,
-                           Class<? extends Annotation> scopeAnnotation, Annotation annotation) {
+                           Object instance,
+                           ImmutableSet<Dependency<?>> dependencies,
+                           Class<? extends Annotation> scopeAnnotation,
+                           Annotation annotation) {
+        super(InternalProviderInstanceBindingImpl.InitializationTiming.EAGER);
         this.key = key;
         this.scopeAnnotation = scopeAnnotation;
         this.instance = instance;
         this.dependencies = dependencies;
         this.method = method;
-        this.parameterProviders = parameterProviders;
         this.exposed = method.isAnnotationPresent(Exposed.class);
         this.annotation = annotation;
     }
@@ -58,24 +71,19 @@ public abstract class ProviderMethod<T> implements ProviderWithExtensionVisitor<
     /**
      * Creates a {@link ProviderMethod}.
      */
-    static <T> ProviderMethod<T> create(Key<T> key, Method method, Object instance,
+    static <T> ProviderMethod<T> create(Key<T> key,
-                                        ImmutableSet<Dependency<?>> dependencies, List<Provider<?>> parameterProviders,
+                                        Method method,
-                                        Class<? extends Annotation> scopeAnnotation, boolean skipFastClassGeneration,
+                                        Object instance,
+                                        ImmutableSet<Dependency<?>> dependencies,
+                                        Class<? extends Annotation> scopeAnnotation,
+                                        boolean skipFastClassGeneration,
                                         Annotation annotation) {
         int modifiers = method.getModifiers();
-
         if (!Modifier.isPublic(modifiers) ||
                 !Modifier.isPublic(method.getDeclaringClass().getModifiers())) {
             method.setAccessible(true);
         }
-
+        return new ReflectionProviderMethod<>(key, method, instance, dependencies, scopeAnnotation, annotation);
-        return new ReflectionProviderMethod<T>(key,
-                method,
-                instance,
-                dependencies,
-                parameterProviders,
-                scopeAnnotation,
-                annotation);
     }
 
     @Override
@@ -120,27 +128,31 @@ public abstract class ProviderMethod<T> implements ProviderWithExtensionVisitor<
     }
 
     @Override
-    public T get() {
+    void initialize(InjectorImpl injector, Errors errors) throws ErrorsException {
-        Object[] parameters = new Object[parameterProviders.size()];
+        parameterInjectors = injector.getParametersInjectors(dependencies.asList(), errors);
-        for (int i = 0; i < parameters.length; i++) {
-            parameters[i] = parameterProviders.get(i).get();
     }
 
+    @Override
+    protected T doProvision(InternalContext context, Dependency<?> dependency)
+            throws InternalProvisionException {
         try {
-            @SuppressWarnings({"unchecked", "UnnecessaryLocalVariable"})
+            T t = doProvision(SingleParameterInjector.getAll(context, parameterInjectors));
-            T result = (T) doProvision(parameters);
+            if (t == null && !dependency.isNullable()) {
-            return result;
+                InternalProvisionException.onNullInjectedIntoNonNullableDependency(getMethod(), dependency);
+            }
+            return t;
         } catch (IllegalAccessException e) {
             throw new AssertionError(e);
-        } catch (InvocationTargetException e) {
+        } catch (InvocationTargetException userException) {
-            throw Exceptions.rethrowCause(e);
+            Throwable cause = userException.getCause() != null ? userException.getCause() : userException;
+            throw InternalProvisionException.errorInProvider(cause).addSource(getSource());
         }
     }
 
     /**
      * Extension point for our subclasses to implement the provisioning strategy.
      */
-    abstract Object doProvision(Object[] parameters)
+    abstract T doProvision(Object[] parameters)
             throws IllegalAccessException, InvocationTargetException;
 
     @Override
@@ -199,22 +211,21 @@ public abstract class ProviderMethod<T> implements ProviderWithExtensionVisitor<
                                  Method method,
                                  Object instance,
                                  ImmutableSet<Dependency<?>> dependencies,
-                                 List<Provider<?>> parameterProviders,
                                  Class<? extends Annotation> scopeAnnotation,
                                  Annotation annotation) {
             super(key,
                     method,
                     instance,
                     dependencies,
-                    parameterProviders,
                     scopeAnnotation,
                     annotation);
         }
 
+        @SuppressWarnings("unchecked")
         @Override
-        Object doProvision(Object[] parameters) throws IllegalAccessException,
+        T doProvision(Object[] parameters) throws IllegalAccessException,
                 InvocationTargetException {
-            return method.invoke(instance, parameters);
+            return (T) method.invoke(instance, parameters);
         }
     }
 }

src/main/java/com/google/inject/internal/ProviderMethodsModule.java

@@ -1,17 +1,14 @@
 package com.google.inject.internal;
 
-import com.google.common.base.Optional;
 import com.google.common.collect.HashMultimap;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Lists;
 import com.google.common.collect.Multimap;
 import com.google.inject.Binder;
 import com.google.inject.Key;
 import com.google.inject.Module;
-import com.google.inject.Provider;
 import com.google.inject.Provides;
 import com.google.inject.TypeLiteral;
-import com.google.inject.spi.Dependency;
 import com.google.inject.spi.InjectionPoint;
 import com.google.inject.spi.Message;
 import com.google.inject.spi.ModuleAnnotatedMethodScanner;
@@ -21,11 +18,12 @@ import java.lang.annotation.Annotation;
 import java.lang.reflect.Member;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
-import java.util.Set;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Preconditions.checkState;
 
 /**
  * Creates bindings to methods annotated with {@literal @}{@link Provides}. Use the scope and
@@ -34,23 +32,12 @@ import static com.google.common.base.Preconditions.checkNotNull;
  */
 public final class ProviderMethodsModule implements Module {
 
-    private static ModuleAnnotatedMethodScanner PROVIDES_BUILDER =
-            new ModuleAnnotatedMethodScanner() {
-                @Override
-                public <T> Key<T> prepareMethod(
-                        Binder binder, Annotation annotation, Key<T> key, InjectionPoint injectionPoint) {
-                    return key;
-                }
-
-                @Override
-                public Set<? extends Class<? extends Annotation>> annotationClasses() {
-                    return ImmutableSet.of(Provides.class);
-                }
-            };
-
     private final Object delegate;
+
     private final TypeLiteral<?> typeLiteral;
+
     private final boolean skipFastClassGeneration;
+
     private final ModuleAnnotatedMethodScanner scanner;
 
     private ProviderMethodsModule(Object delegate, boolean skipFastClassGeneration,
@@ -65,7 +52,7 @@ public final class ProviderMethodsModule implements Module {
      * Returns a module which creates bindings for provider methods from the given module.
      */
     public static Module forModule(Module module) {
-        return forObject(module, false, PROVIDES_BUILDER);
+        return forObject(module, false, ProvidesMethodScanner.INSTANCE);
     }
 
     /**
@@ -83,7 +70,7 @@ public final class ProviderMethodsModule implements Module {
      * are only interested in Module metadata.
      */
     public static Module forObject(Object object) {
-        return forObject(object, true, PROVIDES_BUILDER);
+        return forObject(object, true, ProvidesMethodScanner.INSTANCE);
     }
 
     private static Module forObject(Object object, boolean skipFastClassGeneration,
@@ -92,63 +79,95 @@ public final class ProviderMethodsModule implements Module {
         if (object instanceof ProviderMethodsModule) {
             return Modules.EMPTY_MODULE;
         }
-
         return new ProviderMethodsModule(object, skipFastClassGeneration, scanner);
     }
 
-    /**
+    public Class<?> getDelegateModuleClass() {
-     * Returns true if a overrides b, assumes that the signatures match
+        return isStaticModule() ? (Class<?>) delegate : delegate.getClass();
-     */
-    private static boolean overrides(Method a, Method b) {
-        // See JLS section 8.4.8.1
-        int modifiers = b.getModifiers();
-        if (Modifier.isPublic(modifiers) || Modifier.isProtected(modifiers)) {
-            return true;
     }
-        if (Modifier.isPrivate(modifiers)) {
+
-            return false;
+    @Override
+    public void configure(Binder binder) {
+        for (ProviderMethod<?> providerMethod : getProviderMethods(binder)) {
+            providerMethod.configure(binder);
         }
-        // b must be package-private
+    }
-        return a.getDeclaringClass().getPackage().equals(b.getDeclaringClass().getPackage());
+
+    private boolean isStaticModule() {
+        return delegate instanceof Class;
     }
 
     public Object getDelegateModule() {
         return delegate;
     }
 
-    @Override
+    public List<ProviderMethod<?>> getProviderMethods(Binder binder) {
-    public synchronized void configure(Binder binder) {
+        List<ProviderMethod<?>> result = null;
-        for (ProviderMethod<?> providerMethod : getProviderMethods(binder)) {
+        List<MethodAndAnnotation> methodsAndAnnotations = null;
-            providerMethod.configure(binder);
+        // The highest class in the type hierarchy that contained a provider method definition.
+        Class<?> superMostClass = getDelegateModuleClass();
+        for (Class<?> c = superMostClass; c != Object.class && c != null; c = c.getSuperclass()) {
+            for (Method method : DeclaredMembers.getDeclaredMethods(c)) {
+                Annotation annotation = getAnnotation(binder, method);
+                if (annotation != null) {
+                    if (isStaticModule()
+                            && !Modifier.isStatic(method.getModifiers())
+                            && !Modifier.isAbstract(method.getModifiers())) {
+                        binder
+                                .skipSources(ProviderMethodsModule.class)
+                                .addError(
+                                        "%s is an instance method, but a class literal was passed. Make this method"
+                                                + " static or pass an instance of the module instead.",
+                                        method);
+                        continue;
                     }
+                    if (result == null) {
+                        result = new ArrayList<>();
+                        methodsAndAnnotations = new ArrayList<>();
                     }
 
-    public List<ProviderMethod<?>> getProviderMethods(Binder binder) {
+                    ProviderMethod<Object> providerMethod = createProviderMethod(binder, method, annotation);
-        List<ProviderMethod<?>> result = Lists.newArrayList();
+                    if (providerMethod != null) {
-        Multimap<Signature, Method> methodsBySignature = HashMultimap.create();
+                        result.add(providerMethod);
-        for (Class<?> c = delegate.getClass(); c != Object.class; c = c.getSuperclass()) {
+                    }
+                    methodsAndAnnotations.add(new MethodAndAnnotation(method, annotation));
+                    superMostClass = c;
+                }
+            }
+        }
+        if (result == null) {
+            // We didn't find anything
+            return ImmutableList.of();
+        }
+        // We have found some provider methods, now we need to check if any were overridden.
+        // We do this as a separate pass to avoid calculating all the signatures when there are no
+        // provides methods, or when all provides methods are defined in a single class.
+        Multimap<Signature, Method> methodsBySignature = null;
+        // We can stop scanning when we see superMostClass, since no superclass method can override
+        // a method in a subclass.  Corrollary, if superMostClass == getDelegateModuleClass(), there can
+        // be no overrides of a provides method.
+        for (Class<?> c = getDelegateModuleClass(); c != superMostClass; c = c.getSuperclass()) {
             for (Method method : c.getDeclaredMethods()) {
-                // private/static methods cannot override or be overridden by other methods, so there is no
-                // point in indexing them.
-                // Skip synthetic methods and bridge methods since java will automatically generate
-                // synthetic overrides in some cases where we don't want to generate an error (e.g.
-                // increasing visibility of a subclass).
                 if (((method.getModifiers() & (Modifier.PRIVATE | Modifier.STATIC)) == 0)
-                        && !method.isBridge() && !method.isSynthetic()) {
+                        && !method.isBridge()
-                    methodsBySignature.put(new Signature(method), method);
+                        && !method.isSynthetic()) {
+                    if (methodsBySignature == null) {
+                        methodsBySignature = HashMultimap.create();
                     }
-                Optional<Annotation> annotation = isProvider(binder, method);
+                    methodsBySignature.put(new Signature(typeLiteral, method), method);
-                if (annotation.isPresent()) {
-                    result.add(createProviderMethod(binder, method, annotation.get()));
                 }
             }
         }
-        // we have found all the providers and now need to identify if any were overridden
+        if (methodsBySignature != null) {
-        // In the worst case this will have O(n^2) in the number of @Provides methods, but that is only
+            // we have found all the signatures and now need to identify if any were overridden
-        // assuming that every method is an override, in general it should be very quick.
+            // In the worst case this will have O(n^2) in the number of @Provides methods, but that is
-        for (ProviderMethod<?> provider : result) {
+            // only assuming that every method is an override, in general it should be very quick.
-            Method method = provider.getMethod();
+            for (MethodAndAnnotation methodAndAnnotation : methodsAndAnnotations) {
-            for (Method matchingSignature : methodsBySignature.get(new Signature(method))) {
+                Method method = methodAndAnnotation.method;
+                Annotation annotation = methodAndAnnotation.annotation;
+
+                for (Method matchingSignature :
+                        methodsBySignature.get(new Signature(typeLiteral, method))) {
                     // matching signature is in the same class or a super class, therefore method cannot be
                     // overridding it.
                     if (matchingSignature.getDeclaringClass().isAssignableFrom(method.getDeclaringClass())) {
@@ -156,79 +175,47 @@ public final class ProviderMethodsModule implements Module {
                     }
                     // now we know matching signature is in a subtype of method.getDeclaringClass()
                     if (overrides(matchingSignature, method)) {
-                    String annotationString = provider.getAnnotation().annotationType() == Provides.class
+                        String annotationString =
-                            ? "@Provides" : "@" + provider.getAnnotation().annotationType().getCanonicalName();
+                                annotation.annotationType() == Provides.class
+                                        ? "@Provides"
+                                        : "@" + annotation.annotationType().getCanonicalName();
                         binder.addError(
-                            "Overriding " + annotationString + " methods is not allowed."
+                                "Overriding "
-                                    + "\n\t" + annotationString + " method: %s\n\toverridden by: %s",
+                                        + annotationString
+                                        + " methods is not allowed."
+                                        + "\n\t"
+                                        + annotationString
+                                        + " method: %s\n\toverridden by: %s",
                                 method,
                                 matchingSignature);
                         break;
                     }
                 }
             }
+        }
         return result;
     }
 
-    /**
+    /** Returns the annotation that is claimed by the scanner, or null if there is none. */
-     * Returns true if the method is a provider.
+    private Annotation getAnnotation(Binder binder, Method method) {
-     *
-     * Synthetic bridge methods are excluded. Starting with JDK 8, javac copies annotations onto
-     * bridge methods (which always have erased signatures).
-     */
-    private Optional<Annotation> isProvider(Binder binder, Method method) {
         if (method.isBridge() || method.isSynthetic()) {
-            return Optional.absent();
+            return null;
         }
         Annotation annotation = null;
         for (Class<? extends Annotation> annotationClass : scanner.annotationClasses()) {
             Annotation foundAnnotation = method.getAnnotation(annotationClass);
             if (foundAnnotation != null) {
                 if (annotation != null) {
-                    binder.addError("More than one annotation claimed by %s on method %s."
+                    binder.addError(
+                            "More than one annotation claimed by %s on method %s."
                                     + " Methods can only have one annotation claimed per scanner.",
                             scanner, method);
-                    return Optional.absent();
+                    return null;
                 }
                 annotation = foundAnnotation;
             }
         }
-        return Optional.fromNullable(annotation);
+        return annotation;
-    }
-
-    private <T> ProviderMethod<T> createProviderMethod(Binder binder, Method method,
-                                                       Annotation annotation) {
-        binder = binder.withSource(method);
-        Errors errors = new Errors(method);
-
-        // prepare the parameter providers
-        InjectionPoint point = InjectionPoint.forMethod(method, typeLiteral);
-        List<Dependency<?>> dependencies = point.getDependencies();
-        List<Provider<?>> parameterProviders = Lists.newArrayList();
-        for (Dependency<?> dependency : point.getDependencies()) {
-            parameterProviders.add(binder.getProvider(dependency));
-        }
-
-        @SuppressWarnings("unchecked") // Define T as the method's return type.
-                TypeLiteral<T> returnType = (TypeLiteral<T>) typeLiteral.getReturnType(method);
-        Key<T> key = getKey(errors, returnType, method, method.getAnnotations());
-        try {
-            key = scanner.prepareMethod(binder, annotation, key, point);
-        } catch (Throwable t) {
-            binder.addError(t);
-        }
-        Class<? extends Annotation> scopeAnnotation
-                = Annotations.findScopeAnnotation(errors, method.getAnnotations());
-        for (Message message : errors.getMessages()) {
-            binder.addError(message);
-        }
-        return ProviderMethod.create(key, method, delegate, ImmutableSet.copyOf(dependencies),
-                parameterProviders, scopeAnnotation, skipFastClassGeneration, annotation);
-    }
-
-    <T> Key<T> getKey(Errors errors, TypeLiteral<T> type, Member member, Annotation[] annotations) {
-        Annotation bindingAnnotation = Annotations.findBindingAnnotation(errors, member, annotations);
-        return bindingAnnotation == null ? Key.get(type) : Key.get(type, bindingAnnotation);
     }
 
     @Override
@@ -243,12 +230,23 @@ public final class ProviderMethodsModule implements Module {
         return delegate.hashCode();
     }
 
-    private final class Signature {
+    private static class MethodAndAnnotation {
+        final Method method;
+        final Annotation annotation;
+
+        MethodAndAnnotation(Method method, Annotation annotation) {
+            this.method = method;
+            this.annotation = annotation;
+        }
+    }
+
+
+    private static class Signature {
         final Class<?>[] parameters;
         final String name;
         final int hashCode;
 
-        Signature(Method method) {
+        Signature(TypeLiteral<?> typeLiteral, Method method) {
             this.name = method.getName();
             // We need to 'resolve' the parameters against the actual class type in case this method uses
             // type parameters.  This is so we can detect overrides of generic superclass methods where
@@ -278,4 +276,75 @@ public final class ProviderMethodsModule implements Module {
             return hashCode;
         }
     }
+
+
+    /** Returns true if a overrides b, assumes that the signatures match */
+    private static boolean overrides(Method a, Method b) {
+        // See JLS section 8.4.8.1
+        int modifiers = b.getModifiers();
+        if (Modifier.isPublic(modifiers) || Modifier.isProtected(modifiers)) {
+            return true;
+        }
+        if (Modifier.isPrivate(modifiers)) {
+            return false;
+        }
+        // b must be package-private
+        return a.getDeclaringClass().getPackage().equals(b.getDeclaringClass().getPackage());
+    }
+
+    private <T> ProviderMethod<T> createProviderMethod(
+            Binder binder, Method method, Annotation annotation) {
+        binder = binder.withSource(method);
+        Errors errors = new Errors(method);
+
+        // prepare the parameter providers
+        InjectionPoint point = InjectionPoint.forMethod(method, typeLiteral);
+        @SuppressWarnings("unchecked") // Define T as the method's return type.
+                TypeLiteral<T> returnType = (TypeLiteral<T>) typeLiteral.getReturnType(method);
+        Key<T> key = getKey(errors, returnType, method, method.getAnnotations());
+        try {
+            key = scanner.prepareMethod(binder, annotation, key, point);
+        } catch (Throwable t) {
+            binder.addError(t);
+        }
+
+        if (Modifier.isAbstract(method.getModifiers())) {
+            checkState(
+                    key == null,
+                    "%s returned a non-null key (%s) for %s. prepareMethod() must return null for abstract"
+                            + " methods",
+                    scanner,
+                    key,
+                    method);
+            return null;
+        } else {
+            checkState(
+                    key != null,
+                    "%s returned a null key for %s. prepareMethod() can only return null for abstract"
+                            + " methods",
+                    scanner,
+                    method);
+        }
+
+        Class<? extends Annotation> scopeAnnotation =
+                Annotations.findScopeAnnotation(errors, method.getAnnotations());
+        for (Message message : errors.getMessages()) {
+            binder.addError(message);
+        }
+
+        return ProviderMethod.create(
+                key,
+                method,
+                isStaticModule() ? null : delegate,
+                ImmutableSet.copyOf(point.getDependencies()),
+                scopeAnnotation,
+                skipFastClassGeneration,
+                annotation);
+    }
+
+    <T> Key<T> getKey(Errors errors, TypeLiteral<T> type, Member member, Annotation[] annotations) {
+        Annotation bindingAnnotation = Annotations.findBindingAnnotation(errors, member, annotations);
+        return bindingAnnotation == null ? Key.get(type) : Key.get(type, bindingAnnotation);
+    }
+
 }

src/main/java/com/google/inject/internal/ProviderToInternalFactoryAdapter.java

@@ -1,12 +1,11 @@
 package com.google.inject.internal;
 
 import com.google.inject.Provider;
-import com.google.inject.ProvisionException;
-import com.google.inject.spi.Dependency;
 
 final class ProviderToInternalFactoryAdapter<T> implements Provider<T> {
 
     private final InjectorImpl injector;
+
     private final InternalFactory<? extends T> internalFactory;
 
     public ProviderToInternalFactoryAdapter(InjectorImpl injector,
@@ -15,23 +14,21 @@ final class ProviderToInternalFactoryAdapter<T> implements Provider<T> {
         this.internalFactory = internalFactory;
     }
 
+    @Override
     public T get() {
-        final Errors errors = new Errors();
+        try (InternalContext context = injector.enterContext()) {
-        try {
-            T t = injector.callInContext(new ContextualCallable<T>() {
-                public T call(InternalContext context) throws ErrorsException {
-                    Dependency dependency = context.getDependency();
             // Always pretend that we are a linked binding, to support
             // scoping implicit bindings.  If we are not actually a linked
             // binding, we'll fail properly elsewhere in the chain.
-                    return internalFactory.get(errors, context, dependency, true);
+            return internalFactory.get(context, context.getDependency(), true);
+        } catch (InternalProvisionException e) {
+            throw e.toProvisionException();
         }
-            });
-            errors.throwIfNewErrors(0);
-            return t;
-        } catch (ErrorsException e) {
-            throw new ProvisionException(errors.merge(e.getErrors()).getMessages());
     }
+
+    /** Exposed for SingletonScope. */
+    InjectorImpl getInjector() {
+        return injector;
     }
 
     @Override

src/main/java/com/google/inject/internal/ProvidesMethodScanner.java

@@ -0,0 +1,159 @@
+package com.google.inject.internal;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.inject.Binder;
+import com.google.inject.Key;
+import com.google.inject.Provides;
+import com.google.inject.TypeLiteral;
+import com.google.inject.multibindings.MapKey;
+import com.google.inject.multibindings.ProvidesIntoMap;
+import com.google.inject.multibindings.ProvidesIntoOptional;
+import com.google.inject.multibindings.ProvidesIntoSet;
+import com.google.inject.spi.InjectionPoint;
+import com.google.inject.spi.ModuleAnnotatedMethodScanner;
+import java.lang.annotation.Annotation;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Set;
+
+/**
+ * A {@link ModuleAnnotatedMethodScanner} that handles the {@link Provides}, {@link ProvidesIntoSet},
+ * {@link ProvidesIntoMap} and {@link ProvidesIntoOptional} annotations.
+ *
+ * <p>This is the default scanner used by ProviderMethodsModule and handles all the built in
+ * annotations.
+ */
+final class ProvidesMethodScanner extends ModuleAnnotatedMethodScanner {
+    static final ProvidesMethodScanner INSTANCE = new ProvidesMethodScanner();
+    private static final ImmutableSet<Class<? extends Annotation>> ANNOTATIONS =
+            ImmutableSet.of(Provides.class, ProvidesIntoSet.class, ProvidesIntoMap.class, ProvidesIntoOptional.class);
+
+    private ProvidesMethodScanner() {}
+
+    @Override
+    public Set<? extends Class<? extends Annotation>> annotationClasses() {
+        return ANNOTATIONS;
+    }
+
+    @SuppressWarnings({"unchecked", "rawtypes"}) // mapKey doesn't know its key type
+    @Override
+    public <T> Key<T> prepareMethod(
+            Binder binder, Annotation annotation, Key<T> key, InjectionPoint injectionPoint) {
+        Method method = (Method) injectionPoint.getMember();
+        AnnotationOrError mapKey = findMapKeyAnnotation(binder, method);
+        if (annotation instanceof Provides) {
+            if (mapKey.annotation != null) {
+                binder.addError("Found a MapKey annotation on non map binding at %s.", method);
+            }
+            // no key rewriting for plain old @Provides
+            return key;
+        }
+        if (annotation instanceof ProvidesIntoSet) {
+            if (mapKey.annotation != null) {
+                binder.addError("Found a MapKey annotation on non map binding at %s.", method);
+            }
+            return RealMultibinder.newRealSetBinder(binder, key).getKeyForNewItem();
+        } else if (annotation instanceof ProvidesIntoMap) {
+            if (mapKey.error) {
+                // Already failed on the MapKey, don't bother doing more work.
+                return key;
+            }
+            if (mapKey.annotation == null) {
+                // If no MapKey, make an error and abort.
+                binder.addError("No MapKey found for map binding at %s.", method);
+                return key;
+            }
+            TypeAndValue typeAndValue = typeAndValueOfMapKey(mapKey.annotation);
+            return RealMapBinder.newRealMapBinder(binder, typeAndValue.type, key)
+                    .getKeyForNewValue(typeAndValue.value);
+        } else if (annotation instanceof ProvidesIntoOptional) {
+            if (mapKey.annotation != null) {
+                binder.addError("Found a MapKey annotation on non map binding at %s.", method);
+            }
+            switch (((ProvidesIntoOptional) annotation).value()) {
+                case DEFAULT:
+                    return RealOptionalBinder.newRealOptionalBinder(binder, key).getKeyForDefaultBinding();
+                case ACTUAL:
+                    return RealOptionalBinder.newRealOptionalBinder(binder, key).getKeyForActualBinding();
+            }
+        }
+        throw new IllegalStateException("Invalid annotation: " + annotation);
+    }
+
+    private static class AnnotationOrError {
+        final Annotation annotation;
+        final boolean error;
+
+        AnnotationOrError(Annotation annotation, boolean error) {
+            this.annotation = annotation;
+            this.error = error;
+        }
+
+        static AnnotationOrError forPossiblyNullAnnotation(Annotation annotation) {
+            return new AnnotationOrError(annotation, false);
+        }
+
+        static AnnotationOrError forError() {
+            return new AnnotationOrError(null, true);
+        }
+    }
+
+    private static AnnotationOrError findMapKeyAnnotation(Binder binder, Method method) {
+        Annotation foundAnnotation = null;
+        for (Annotation annotation : method.getAnnotations()) {
+            MapKey mapKey = annotation.annotationType().getAnnotation(MapKey.class);
+            if (mapKey != null) {
+                if (foundAnnotation != null) {
+                    binder.addError("Found more than one MapKey annotations on %s.", method);
+                    return AnnotationOrError.forError();
+                }
+                if (mapKey.unwrapValue()) {
+                    try {
+                        // validate there's a declared method called "value"
+                        Method valueMethod = annotation.annotationType().getDeclaredMethod("value");
+                        if (valueMethod.getReturnType().isArray()) {
+                            binder.addError(
+                                    "Array types are not allowed in a MapKey with unwrapValue=true: %s",
+                                    annotation.annotationType());
+                            return AnnotationOrError.forError();
+                        }
+                    } catch (NoSuchMethodException invalid) {
+                        binder.addError(
+                                "No 'value' method in MapKey with unwrapValue=true: %s",
+                                annotation.annotationType());
+                        return AnnotationOrError.forError();
+                    }
+                }
+                foundAnnotation = annotation;
+            }
+        }
+        return AnnotationOrError.forPossiblyNullAnnotation(foundAnnotation);
+    }
+
+    @SuppressWarnings({"unchecked", "rawtypes"})
+    private static TypeAndValue<?> typeAndValueOfMapKey(Annotation mapKeyAnnotation) {
+        if (!mapKeyAnnotation.annotationType().getAnnotation(MapKey.class).unwrapValue()) {
+            return new TypeAndValue(TypeLiteral.get(mapKeyAnnotation.annotationType()), mapKeyAnnotation);
+        } else {
+            try {
+                Method valueMethod = mapKeyAnnotation.annotationType().getDeclaredMethod("value");
+                valueMethod.setAccessible(true);
+                TypeLiteral<?> returnType =
+                        TypeLiteral.get(mapKeyAnnotation.annotationType()).getReturnType(valueMethod);
+                return new TypeAndValue(returnType, valueMethod.invoke(mapKeyAnnotation));
+            } catch (NoSuchMethodException | SecurityException | IllegalAccessException | InvocationTargetException e) {
+                throw new IllegalStateException(e);
+            }
+        }
+    }
+
+    private static class TypeAndValue<T> {
+        final TypeLiteral<T> type;
+        final T value;
+
+        TypeAndValue(TypeLiteral<T> type, T value) {
+            this.type = type;
+            this.value = value;
+        }
+    }
+}

src/main/java/com/google/inject/internal/ProvisionListenerCallbackStore.java

@@ -29,9 +29,9 @@ final class ProvisionListenerCallbackStore {
 
     private final ImmutableList<ProvisionListenerBinding> listenerBindings;
 
-    private final LoadingCache<KeyBinding, ProvisionListenerStackCallback<?>> cache
+    private final LoadingCache<KeyBinding, ProvisionListenerStackCallback<?>> cache = CacheBuilder.newBuilder().build(
-            = CacheBuilder.newBuilder().build(
+            new CacheLoader<>() {
-            new CacheLoader<KeyBinding, ProvisionListenerStackCallback<?>>() {
+                @Override
                 public ProvisionListenerStackCallback<?> load(KeyBinding key) {
                     return create(key.binding);
                 }

src/main/java/com/google/inject/internal/ProvisionListenerStackCallback.java

@@ -3,8 +3,6 @@ package com.google.inject.internal;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Sets;
 import com.google.inject.Binding;
-import com.google.inject.ProvisionException;
-import com.google.inject.spi.DependencyAndSource;
 import com.google.inject.spi.ProvisionListener;
 
 import java.util.List;
@@ -16,7 +14,8 @@ import java.util.Set;
  */
 final class ProvisionListenerStackCallback<T> {
 
-    private static final ProvisionListener EMPTY_LISTENER[] = new ProvisionListener[0];
+    private static final ProvisionListener[] EMPTY_LISTENER = new ProvisionListener[0];
+
     @SuppressWarnings({"rawtypes", "unchecked"})
     private static final ProvisionListenerStackCallback<?> EMPTY_CALLBACK =
             new ProvisionListenerStackCallback(null /* unused, so ok */, ImmutableList.of());
@@ -43,9 +42,9 @@ final class ProvisionListenerStackCallback<T> {
         return listeners.length > 0;
     }
 
-    public T provision(Errors errors, InternalContext context, ProvisionCallback<T> callable)
+    public T provision(InternalContext context, ProvisionCallback<T> callable)
-            throws ErrorsException {
+            throws InternalProvisionException {
-        Provision provision = new Provision(errors, context, callable);
+        Provision provision = new Provision(context, callable);
         RuntimeException caught = null;
         try {
             provision.provision();
@@ -56,12 +55,14 @@ final class ProvisionListenerStackCallback<T> {
         if (provision.exceptionDuringProvision != null) {
             throw provision.exceptionDuringProvision;
         } else if (caught != null) {
-            Object listener = provision.erredListener != null ?
+            Object listener =
-                    provision.erredListener.getClass() : "(unknown)";
+                    provision.erredListener != null ? provision.erredListener.getClass() : "(unknown)";
-            throw errors
+            throw InternalProvisionException.errorInUserCode(
-                    .errorInUserCode(caught, "Error notifying ProvisionListener %s of %s.%n"
+                    caught,
-                            + " Reason: %s", listener, binding.getKey(), caught)
+                    "Error notifying ProvisionListener %s of %s.%n Reason: %s",
-                    .toException();
+                    listener,
+                    binding.getKey(),
+                    caught);
         } else {
             return provision.result;
         }
@@ -69,25 +70,21 @@ final class ProvisionListenerStackCallback<T> {
 
     // TODO(sameb): Can this be more InternalFactory-like?
     public interface ProvisionCallback<T> {
-        T call() throws ErrorsException;
+        T call() throws InternalProvisionException;
     }
 
     private class Provision extends ProvisionListener.ProvisionInvocation<T> {
 
-        final Errors errors;
-        final int numErrorsBefore;
         final InternalContext context;
         final ProvisionCallback<T> callable;
         int index = -1;
         T result;
-        ErrorsException exceptionDuringProvision;
+        InternalProvisionException exceptionDuringProvision;
         ProvisionListener erredListener;
 
-        public Provision(Errors errors, InternalContext context, ProvisionCallback<T> callable) {
+        public Provision(InternalContext context, ProvisionCallback<T> callable) {
             this.callable = callable;
             this.context = context;
-            this.errors = errors;
-            this.numErrorsBefore = errors.size();
         }
 
         @Override
@@ -96,12 +93,9 @@ final class ProvisionListenerStackCallback<T> {
             if (index == listeners.length) {
                 try {
                     result = callable.call();
-                    // Make sure we don't return the provisioned object if there were any errors
+                } catch (InternalProvisionException ipe) {
-                    // injecting its field/method dependencies.
+                    exceptionDuringProvision = ipe;
-                    errors.throwIfNewErrors(numErrorsBefore);
+                    throw ipe.toProvisionException();
-                } catch (ErrorsException ee) {
-                    exceptionDuringProvision = ee;
-                    throw new ProvisionException(errors.merge(ee.getErrors()).getMessages());
                 }
             } else if (index < listeners.length) {
                 int currentIdx = index;
@@ -128,10 +122,5 @@ final class ProvisionListenerStackCallback<T> {
             // if someone calls that they'll get strange errors.
             return binding;
         }
-
-        @Override
-        public List<DependencyAndSource> getDependencyChain() {
-            return context.getDependencyChain();
-        }
     }
 }

src/main/java/com/google/inject/internal/RealElement.java

@@ -1,7 +1,6 @@
-package com.google.inject.multibindings;
+package com.google.inject.internal;
 
 import com.google.inject.Key;
-import com.google.inject.internal.Annotations;
 
 import java.lang.annotation.Annotation;
 import java.util.concurrent.atomic.AtomicInteger;

src/main/java/com/google/inject/internal/RealMultibinder.java

@@ -0,0 +1,611 @@
+package com.google.inject.internal;
+
+import static com.google.inject.internal.Element.Type.MULTIBINDER;
+import static com.google.inject.internal.Errors.checkConfiguration;
+import static com.google.inject.internal.Errors.checkNotNull;
+import static com.google.inject.name.Names.named;
+
+import com.google.common.base.Objects;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
+import com.google.inject.AbstractModule;
+import com.google.inject.Binder;
+import com.google.inject.Binding;
+import com.google.inject.Injector;
+import com.google.inject.Key;
+import com.google.inject.Module;
+import com.google.inject.Provider;
+import com.google.inject.TypeLiteral;
+import com.google.inject.binder.LinkedBindingBuilder;
+import com.google.inject.internal.InternalProviderInstanceBindingImpl.InitializationTiming;
+import com.google.inject.multibindings.MultibinderBinding;
+import com.google.inject.multibindings.MultibindingsTargetVisitor;
+import com.google.inject.spi.BindingTargetVisitor;
+import com.google.inject.spi.Dependency;
+import com.google.inject.spi.ProviderInstanceBinding;
+import com.google.inject.spi.ProviderWithExtensionVisitor;
+import com.google.inject.util.Types;
+import java.lang.reflect.Type;
+import java.util.Collection;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * The actual multibinder plays several roles:
+ *
+ * <p>As a Multibinder, it acts as a factory for LinkedBindingBuilders for each of the set's
+ * elements. Each binding is given an annotation that identifies it as a part of this set.
+ *
+ * <p>As a Module, it installs the binding to the set itself. As a module, this implements equals()
+ * and hashcode() in order to trick Guice into executing its configure() method only once. That
+ * makes it so that multiple multibinders can be created for the same target collection, but only
+ * one is bound. Since the list of bindings is retrieved from the injector itself (and not the
+ * multibinder), each multibinder has access to all contributions from all multibinders.
+ *
+ * <p>As a Provider, this constructs the set instances.
+ *
+ * <p>We use a subclass to hide 'implements Module, Provider' from the public API.
+ */
+public final class RealMultibinder<T> implements Module {
+
+    /** Implementation of newSetBinder. */
+    public static <T> RealMultibinder<T> newRealSetBinder(Binder binder, Key<T> key) {
+        binder = binder.skipSources(RealMultibinder.class);
+        RealMultibinder<T> result = new RealMultibinder<>(binder, key);
+        binder.install(result);
+        return result;
+    }
+
+    @SuppressWarnings("unchecked") // wrapping a T in a Set safely returns a Set<T>
+    static <T> TypeLiteral<Set<T>> setOf(TypeLiteral<T> elementType) {
+        Type type = Types.setOf(elementType.getType());
+        return (TypeLiteral<Set<T>>) TypeLiteral.get(type);
+    }
+
+    @SuppressWarnings("unchecked")
+    static <T> TypeLiteral<Collection<Provider<T>>> collectionOfProvidersOf(
+            TypeLiteral<T> elementType) {
+        Type providerType = Types.providerOf(elementType.getType());
+        Type type = Types.collectionOf(providerType);
+        return (TypeLiteral<Collection<Provider<T>>>) TypeLiteral.get(type);
+    }
+
+    @SuppressWarnings("unchecked")
+    static <T> TypeLiteral<Collection<javax.inject.Provider<T>>> collectionOfJavaxProvidersOf(
+            TypeLiteral<T> elementType) {
+        Type providerType =
+                Types.newParameterizedType(javax.inject.Provider.class, elementType.getType());
+        Type type = Types.collectionOf(providerType);
+        return (TypeLiteral<Collection<javax.inject.Provider<T>>>) TypeLiteral.get(type);
+    }
+
+    private final BindingSelection<T> bindingSelection;
+    private final Binder binder;
+
+    RealMultibinder(Binder binder, Key<T> key) {
+        this.binder = checkNotNull(binder, "binder");
+        this.bindingSelection = new BindingSelection<>(key);
+    }
+
+    @Override
+    public void configure(Binder binder) {
+        checkConfiguration(!bindingSelection.isInitialized(), "Multibinder was already initialized");
+        binder
+                .bind(bindingSelection.getSetKey())
+                .toProvider(new RealMultibinderProvider<T>(bindingSelection));
+        Provider<Collection<Provider<T>>> collectionOfProvidersProvider =
+                new RealMultibinderCollectionOfProvidersProvider<T>(bindingSelection);
+        binder
+                .bind(bindingSelection.getCollectionOfProvidersKey())
+                .toProvider(collectionOfProvidersProvider);
+
+        // The collection this exposes is internally an ImmutableList, so it's OK to massage
+        // the guice Provider to javax Provider in the value (since the guice Provider implements
+        // javax Provider).
+        @SuppressWarnings("unchecked")
+        Provider<Collection<javax.inject.Provider<T>>> javaxProvider =
+                (Provider) collectionOfProvidersProvider;
+        binder.bind(bindingSelection.getCollectionOfJavaxProvidersKey()).toProvider(javaxProvider);
+    }
+
+    public void permitDuplicates() {
+        binder.install(new PermitDuplicatesModule(bindingSelection.getPermitDuplicatesKey()));
+    }
+
+    /** Adds a new entry to the set and returns the key for it. */
+    Key<T> getKeyForNewItem() {
+        checkConfiguration(!bindingSelection.isInitialized(), "Multibinder was already initialized");
+        return Key.get(
+                bindingSelection.getElementTypeLiteral(),
+                new RealElement(bindingSelection.getSetName(), MULTIBINDER, ""));
+    }
+
+    public LinkedBindingBuilder<T> addBinding() {
+        return binder.bind(getKeyForNewItem());
+    }
+
+    // These methods are used by RealMapBinder
+
+    Key<Set<T>> getSetKey() {
+        return bindingSelection.getSetKey();
+    }
+
+    TypeLiteral<T> getElementTypeLiteral() {
+        return bindingSelection.getElementTypeLiteral();
+    }
+
+    String getSetName() {
+        return bindingSelection.getSetName();
+    }
+
+    boolean permitsDuplicates(Injector injector) {
+        return bindingSelection.permitsDuplicates(injector);
+    }
+
+    boolean containsElement(com.google.inject.spi.Element element) {
+        return bindingSelection.containsElement(element);
+    }
+
+    private static final class RealMultibinderProvider<T>
+            extends InternalProviderInstanceBindingImpl.Factory<Set<T>>
+            implements ProviderWithExtensionVisitor<Set<T>>, MultibinderBinding<Set<T>> {
+        private final BindingSelection<T> bindingSelection;
+        private List<Binding<T>> bindings;
+        private SingleParameterInjector<T>[] injectors;
+        private boolean permitDuplicates;
+
+        RealMultibinderProvider(BindingSelection<T> bindingSelection) {
+            // While Multibinders only depend on bindings created in modules so we could theoretically
+            // initialize eagerly, they also depend on
+            // 1. findBindingsByType returning results
+            // 2. being able to call BindingImpl.acceptTargetVisitor
+            // neither of those is available during eager initialization, so we use DELAYED
+            super(InitializationTiming.DELAYED);
+            this.bindingSelection = bindingSelection;
+        }
+
+        @Override
+        public Set<Dependency<?>> getDependencies() {
+            return bindingSelection.getDependencies();
+        }
+
+        @Override
+        void initialize(InjectorImpl injector, Errors errors) throws ErrorsException {
+            bindingSelection.initialize(injector, errors);
+            this.bindings = bindingSelection.getBindings();
+            this.injectors = bindingSelection.getParameterInjectors();
+            this.permitDuplicates = bindingSelection.permitsDuplicates();
+        }
+
+        @Override
+        protected Set<T> doProvision(InternalContext context, Dependency<?> dependency)
+                throws InternalProvisionException {
+            SingleParameterInjector<T>[] localInjectors = injectors;
+            if (localInjectors == null) {
+                // if localInjectors == null, then we have no bindings so return the empty set.
+                return ImmutableSet.of();
+            }
+            // Ideally we would just add to an ImmutableSet.Builder, but if we did that and there were
+            // duplicates we wouldn't be able to tell which one was the duplicate.  So to manage this we
+            // first put everything into an array and then construct the set.  This way if something gets
+            // dropped we can figure out what it is.
+            @SuppressWarnings("unchecked")
+            T[] values = (T[]) new Object[localInjectors.length];
+            for (int i = 0; i < localInjectors.length; i++) {
+                SingleParameterInjector<T> parameterInjector = localInjectors[i];
+                T newValue = parameterInjector.inject(context);
+                if (newValue == null) {
+                    throw newNullEntryException(i);
+                }
+                values[i] = newValue;
+            }
+            ImmutableSet<T> set = ImmutableSet.copyOf(values);
+            // There are fewer items in the set than the array.  Figure out which one got dropped.
+            if (!permitDuplicates && set.size() < values.length) {
+                throw newDuplicateValuesException(set, values);
+            }
+            return set;
+        }
+
+        private InternalProvisionException newNullEntryException(int i) {
+            return InternalProvisionException.create(
+                    "Set injection failed due to null element bound at: %s", bindings.get(i).getSource());
+        }
+
+        @SuppressWarnings("unchecked")
+        @Override
+        public <B, V> V acceptExtensionVisitor(
+                BindingTargetVisitor<B, V> visitor, ProviderInstanceBinding<? extends B> binding) {
+            if (visitor instanceof MultibindingsTargetVisitor) {
+                return ((MultibindingsTargetVisitor<Set<T>, V>) visitor).visit(this);
+            } else {
+                return visitor.visit(binding);
+            }
+        }
+
+        private InternalProvisionException newDuplicateValuesException(
+                ImmutableSet<T> set, T[] values) {
+            // TODO(lukes): consider reporting all duplicate values, the easiest way would be to rebuild
+            // a new set and detect dupes as we go
+            // Find the duplicate binding
+            // To do this we take advantage of the fact that set, values and bindings all have the same
+            // ordering for a non-empty prefix of the set.
+            // First we scan for the first item dropped from the set.
+            int newBindingIndex = 0;
+            for (T item : set) {
+                if (item != values[newBindingIndex]) {
+                    break;
+                }
+                newBindingIndex++;
+            }
+            // once we exit the loop newBindingIndex will point at the first item in values that was
+            // dropped.
+
+            Binding<T> newBinding = bindings.get(newBindingIndex);
+            T newValue = values[newBindingIndex];
+            // Now we scan again to find the index of the value, we are guaranteed to find it.
+            int oldBindingIndex = set.asList().indexOf(newValue);
+            T oldValue = values[oldBindingIndex];
+            Binding<T> duplicateBinding = bindings.get(oldBindingIndex);
+            String oldString = oldValue.toString();
+            String newString = newValue.toString();
+            if (Objects.equal(oldString, newString)) {
+                // When the value strings match, just show the source of the bindings
+                return InternalProvisionException.create(
+                        "Set injection failed due to duplicated element \"%s\""
+                                + "\n    Bound at %s\n    Bound at %s",
+                        newValue, duplicateBinding.getSource(), newBinding.getSource());
+            } else {
+                // When the value strings don't match, include them both as they may be useful for debugging
+                return InternalProvisionException.create(
+                        "Set injection failed due to multiple elements comparing equal:"
+                                + "\n    \"%s\"\n        bound at %s"
+                                + "\n    \"%s\"\n        bound at %s",
+                        oldValue, duplicateBinding.getSource(), newValue, newBinding.getSource());
+            }
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            return obj instanceof RealMultibinderProvider
+                    && bindingSelection.equals(((RealMultibinderProvider<?>) obj).bindingSelection);
+        }
+
+        @Override
+        public int hashCode() {
+            return bindingSelection.hashCode();
+        }
+
+        @Override
+        public Key<Set<T>> getSetKey() {
+            return bindingSelection.getSetKey();
+        }
+
+        @Override
+        public Set<Key<?>> getAlternateSetKeys() {
+            return ImmutableSet.of(
+                    (Key<?>) bindingSelection.getCollectionOfProvidersKey(),
+                    (Key<?>) bindingSelection.getCollectionOfJavaxProvidersKey());
+        }
+
+        @Override
+        public TypeLiteral<?> getElementTypeLiteral() {
+            return bindingSelection.getElementTypeLiteral();
+        }
+
+        @Override
+        public List<Binding<?>> getElements() {
+            return bindingSelection.getElements();
+        }
+
+        @Override
+        public boolean permitsDuplicates() {
+            return bindingSelection.permitsDuplicates();
+        }
+
+        @Override
+        public boolean containsElement(com.google.inject.spi.Element element) {
+            return bindingSelection.containsElement(element);
+        }
+    }
+
+    private static final class BindingSelection<T> {
+        // prior to initialization we declare just a dependency on the injector, but as soon as we are
+        // initialized we swap to dependencies on the elements.
+        private static final ImmutableSet<Dependency<?>> MODULE_DEPENDENCIES =
+                ImmutableSet.<Dependency<?>>of(Dependency.get(Key.get(Injector.class)));
+        private final TypeLiteral<T> elementType;
+        private final Key<Set<T>> setKey;
+
+        // these are all lazily allocated
+        private String setName;
+        private Key<Collection<Provider<T>>> collectionOfProvidersKey;
+        private Key<Collection<javax.inject.Provider<T>>> collectionOfJavaxProvidersKey;
+        private Key<Boolean> permitDuplicatesKey;
+
+        private boolean isInitialized;
+        /* a binding for each element in the set. null until initialization, non-null afterwards */
+        private ImmutableList<Binding<T>> bindings;
+
+        // Starts out as Injector and gets set up properly after initialization
+        private ImmutableSet<Dependency<?>> dependencies = MODULE_DEPENDENCIES;
+        private ImmutableSet<Dependency<?>> providerDependencies = MODULE_DEPENDENCIES;
+
+        /** whether duplicates are allowed. Possibly configured by a different instance */
+        private boolean permitDuplicates;
+
+        private SingleParameterInjector<T>[] parameterinjectors;
+
+        BindingSelection(Key<T> key) {
+            this.setKey = key.ofType(setOf(key.getTypeLiteral()));
+            this.elementType = key.getTypeLiteral();
+        }
+
+        void initialize(InjectorImpl injector, Errors errors) throws ErrorsException {
+            // This will be called multiple times, once by each Factory. We only want
+            // to do the work to initialize everything once, so guard this code with
+            // isInitialized.
+            if (isInitialized) {
+                return;
+            }
+            List<Binding<T>> bindings = Lists.newArrayList();
+            Set<Indexer.IndexedBinding> index = Sets.newHashSet();
+            Indexer indexer = new Indexer(injector);
+            List<Dependency<?>> dependencies = Lists.newArrayList();
+            List<Dependency<?>> providerDependencies = Lists.newArrayList();
+            for (Binding<?> entry : injector.findBindingsByType(elementType)) {
+                if (keyMatches(entry.getKey())) {
+                    @SuppressWarnings("unchecked") // protected by findBindingsByType()
+                            Binding<T> binding = (Binding<T>) entry;
+                    if (index.add(binding.acceptTargetVisitor(indexer))) {
+                        // TODO(lukes): most of these are linked bindings since user bindings are linked to
+                        // a user binding through the @Element annotation.  Since this is an implementation
+                        // detail we could 'dereference' the @Element if it is a LinkedBinding and avoid
+                        // provisioning through the FactoryProxy at runtime.
+                        // Ditto for OptionalBinder/MapBinder
+                        bindings.add(binding);
+                        Key<T> key = binding.getKey();
+                        // TODO(lukes): we should mark this as a non-nullable dependency since we don't accept
+                        // null.
+                        // Add a dependency on Key<T>
+                        dependencies.add(Dependency.get(key));
+                        // and add a dependency on Key<Provider<T>>
+                        providerDependencies.add(
+                                Dependency.get(key.ofType(Types.providerOf(key.getTypeLiteral().getType()))));
+                    }
+                }
+            }
+
+            this.bindings = ImmutableList.copyOf(bindings);
+            this.dependencies = ImmutableSet.copyOf(dependencies);
+            this.providerDependencies = ImmutableSet.copyOf(providerDependencies);
+            this.permitDuplicates = permitsDuplicates(injector);
+            // This is safe because all our dependencies are assignable to T and we never assign to
+            // elements of this array.
+            @SuppressWarnings("unchecked")
+            SingleParameterInjector<T>[] typed =
+                    (SingleParameterInjector<T>[]) injector.getParametersInjectors(dependencies, errors);
+            this.parameterinjectors = typed;
+            isInitialized = true;
+        }
+
+        boolean permitsDuplicates(Injector injector) {
+            return injector.getBindings().containsKey(getPermitDuplicatesKey());
+        }
+
+        ImmutableList<Binding<T>> getBindings() {
+            checkConfiguration(isInitialized, "not initialized");
+            return bindings;
+        }
+
+        SingleParameterInjector<T>[] getParameterInjectors() {
+            checkConfiguration(isInitialized, "not initialized");
+            return parameterinjectors;
+        }
+
+        ImmutableSet<Dependency<?>> getDependencies() {
+            return dependencies;
+        }
+
+        ImmutableSet<Dependency<?>> getProviderDependencies() {
+            return providerDependencies;
+        }
+
+        String getSetName() {
+            // lazily initialized since most selectors don't survive module installation.
+            if (setName == null) {
+                setName = Annotations.nameOf(setKey);
+            }
+            return setName;
+        }
+
+        Key<Boolean> getPermitDuplicatesKey() {
+            Key<Boolean> local = permitDuplicatesKey;
+            if (local == null) {
+                local =
+                        permitDuplicatesKey = Key.get(Boolean.class, named(toString() + " permits duplicates"));
+            }
+            return local;
+        }
+
+        Key<Collection<Provider<T>>> getCollectionOfProvidersKey() {
+            Key<Collection<Provider<T>>> local = collectionOfProvidersKey;
+            if (local == null) {
+                local = collectionOfProvidersKey = setKey.ofType(collectionOfProvidersOf(elementType));
+            }
+            return local;
+        }
+
+        Key<Collection<javax.inject.Provider<T>>> getCollectionOfJavaxProvidersKey() {
+            Key<Collection<javax.inject.Provider<T>>> local = collectionOfJavaxProvidersKey;
+            if (local == null) {
+                local =
+                        collectionOfJavaxProvidersKey =
+                                setKey.ofType(collectionOfJavaxProvidersOf(elementType));
+            }
+            return local;
+        }
+
+        boolean isInitialized() {
+            return isInitialized;
+        }
+
+        // MultibinderBinding API methods
+
+        TypeLiteral<T> getElementTypeLiteral() {
+            return elementType;
+        }
+
+        Key<Set<T>> getSetKey() {
+            return setKey;
+        }
+
+        @SuppressWarnings("unchecked")
+        List<Binding<?>> getElements() {
+            if (isInitialized()) {
+                return (List<Binding<?>>) (List<?>) bindings; // safe because bindings is immutable.
+            } else {
+                throw new UnsupportedOperationException("getElements() not supported for module bindings");
+            }
+        }
+
+        boolean permitsDuplicates() {
+            if (isInitialized()) {
+                return permitDuplicates;
+            } else {
+                throw new UnsupportedOperationException(
+                        "permitsDuplicates() not supported for module bindings");
+            }
+        }
+
+        boolean containsElement(com.google.inject.spi.Element element) {
+            if (element instanceof Binding) {
+                Binding<?> binding = (Binding<?>) element;
+                return keyMatches(binding.getKey())
+                        || binding.getKey().equals(getPermitDuplicatesKey())
+                        || binding.getKey().equals(setKey)
+                        || binding.getKey().equals(collectionOfProvidersKey)
+                        || binding.getKey().equals(collectionOfJavaxProvidersKey);
+            } else {
+                return false;
+            }
+        }
+
+        private boolean keyMatches(Key<?> key) {
+            return key.getTypeLiteral().equals(elementType)
+                    && key.getAnnotation() instanceof Element
+                    && ((Element) key.getAnnotation()).setName().equals(getSetName())
+                    && ((Element) key.getAnnotation()).type() == MULTIBINDER;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (obj instanceof BindingSelection) {
+                return setKey.equals(((BindingSelection<?>) obj).setKey);
+            }
+            return false;
+        }
+
+        @Override
+        public int hashCode() {
+            return setKey.hashCode();
+        }
+
+        @Override
+        public String toString() {
+            return (getSetName().isEmpty() ? "" : getSetName() + " ")
+                    + "Multibinder<"
+                    + elementType
+                    + ">";
+        }
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        return o instanceof RealMultibinder
+                && ((RealMultibinder<?>) o).bindingSelection.equals(bindingSelection);
+    }
+
+    @Override
+    public int hashCode() {
+        return bindingSelection.hashCode();
+    }
+
+    private static final class RealMultibinderCollectionOfProvidersProvider<T>
+            extends InternalProviderInstanceBindingImpl.Factory<Collection<Provider<T>>> {
+
+        private final BindingSelection<T> bindingSelection;
+        private ImmutableList<Provider<T>> collectionOfProviders;
+
+        RealMultibinderCollectionOfProvidersProvider(BindingSelection<T> bindingSelection) {
+            super(InitializationTiming.DELAYED); // See comment in RealMultibinderProvider
+            this.bindingSelection = bindingSelection;
+        }
+
+        @Override
+        void initialize(InjectorImpl injector, Errors errors) throws ErrorsException {
+            bindingSelection.initialize(injector, errors);
+            ImmutableList.Builder<Provider<T>> providers = ImmutableList.builder();
+            for (Binding<T> binding : bindingSelection.getBindings()) {
+                providers.add(binding.getProvider());
+            }
+            this.collectionOfProviders = providers.build();
+        }
+
+        @Override
+        protected Collection<Provider<T>> doProvision(
+                InternalContext context, Dependency<?> dependency) {
+            return collectionOfProviders;
+        }
+
+        @Override
+        public Set<Dependency<?>> getDependencies() {
+            return bindingSelection.getProviderDependencies();
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            return obj instanceof RealMultibinderCollectionOfProvidersProvider
+                    && bindingSelection.equals(
+                    ((RealMultibinderCollectionOfProvidersProvider<?>) obj).bindingSelection);
+        }
+
+        @Override
+        public int hashCode() {
+            return bindingSelection.hashCode();
+        }
+    }
+
+    /**
+     * We install the permit duplicates configuration as its own binding, all by itself. This way, if
+     * only one of a multibinder's users remember to call permitDuplicates(), they're still permitted.
+     *
+     * <p>This is like setting a global variable in the injector so that each instance of the
+     * multibinder will have the same value for permitDuplicates, even if it is only set on one of
+     * them.
+     */
+    private static class PermitDuplicatesModule extends AbstractModule {
+        private final Key<Boolean> key;
+
+        PermitDuplicatesModule(Key<Boolean> key) {
+            this.key = key;
+        }
+
+        @Override
+        protected void configure() {
+            bind(key).toInstance(true);
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            return o instanceof PermitDuplicatesModule && ((PermitDuplicatesModule) o).key.equals(key);
+        }
+
+        @Override
+        public int hashCode() {
+            return getClass().hashCode() ^ key.hashCode();
+        }
+    }
+}

src/main/java/com/google/inject/internal/RealOptionalBinder.java

@@ -0,0 +1,793 @@
+package com.google.inject.internal;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.inject.internal.Errors.checkConfiguration;
+import static com.google.inject.util.Types.newParameterizedType;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.base.Optional;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Iterables;
+import com.google.inject.Binder;
+import com.google.inject.Binding;
+import com.google.inject.Injector;
+import com.google.inject.Key;
+import com.google.inject.Module;
+import com.google.inject.Provider;
+import com.google.inject.TypeLiteral;
+import com.google.inject.binder.LinkedBindingBuilder;
+import com.google.inject.internal.InternalProviderInstanceBindingImpl.InitializationTiming;
+import com.google.inject.multibindings.MultibindingsTargetVisitor;
+import com.google.inject.multibindings.OptionalBinderBinding;
+import com.google.inject.spi.BindingTargetVisitor;
+import com.google.inject.spi.Dependency;
+import com.google.inject.spi.Element;
+import com.google.inject.spi.ProviderInstanceBinding;
+import com.google.inject.spi.ProviderWithExtensionVisitor;
+import com.google.inject.util.Types;
+import java.io.Serializable;
+import java.lang.annotation.Annotation;
+import java.lang.annotation.Retention;
+import java.lang.reflect.Type;
+import java.util.Set;
+import javax.inject.Qualifier;
+
+/**
+ * The actual OptionalBinder plays several roles. It implements Module to hide that fact from the
+ * public API, and installs the various bindings that are exposed to the user.
+ */
+public final class RealOptionalBinder<T> implements Module {
+    public static <T> RealOptionalBinder<T> newRealOptionalBinder(Binder binder, Key<T> type) {
+        binder = binder.skipSources(RealOptionalBinder.class);
+        RealOptionalBinder<T> optionalBinder = new RealOptionalBinder<>(binder, type);
+        binder.install(optionalBinder);
+        return optionalBinder;
+    }
+
+    @SuppressWarnings("unchecked")
+    static <T> TypeLiteral<Optional<T>> optionalOf(TypeLiteral<T> type) {
+        return (TypeLiteral<Optional<T>>)
+                TypeLiteral.get(Types.newParameterizedType(Optional.class, type.getType()));
+    }
+
+    @SuppressWarnings("unchecked")
+    static <T> TypeLiteral<java.util.Optional<T>> javaOptionalOf(TypeLiteral<T> type) {
+        return (TypeLiteral<java.util.Optional<T>>)
+                TypeLiteral.get(Types.newParameterizedType(java.util.Optional.class, type.getType()));
+    }
+
+    @SuppressWarnings("unchecked")
+    static <T> TypeLiteral<Optional<javax.inject.Provider<T>>> optionalOfJavaxProvider(
+            TypeLiteral<T> type) {
+        return (TypeLiteral<Optional<javax.inject.Provider<T>>>)
+                TypeLiteral.get(
+                        Types.newParameterizedType(
+                                Optional.class, newParameterizedType(javax.inject.Provider.class, type.getType())));
+    }
+
+    @SuppressWarnings("unchecked")
+    static <T> TypeLiteral<java.util.Optional<javax.inject.Provider<T>>> javaOptionalOfJavaxProvider(
+            TypeLiteral<T> type) {
+        return (TypeLiteral<java.util.Optional<javax.inject.Provider<T>>>)
+                TypeLiteral.get(
+                        Types.newParameterizedType(
+                                java.util.Optional.class,
+                                newParameterizedType(javax.inject.Provider.class, type.getType())));
+    }
+
+    @SuppressWarnings("unchecked")
+    static <T> TypeLiteral<Optional<Provider<T>>> optionalOfProvider(TypeLiteral<T> type) {
+        return (TypeLiteral<Optional<Provider<T>>>)
+                TypeLiteral.get(
+                        Types.newParameterizedType(
+                                Optional.class, newParameterizedType(Provider.class, type.getType())));
+    }
+
+    @SuppressWarnings("unchecked")
+    static <T> TypeLiteral<java.util.Optional<Provider<T>>> javaOptionalOfProvider(
+            TypeLiteral<T> type) {
+        return (TypeLiteral<java.util.Optional<Provider<T>>>)
+                TypeLiteral.get(
+                        Types.newParameterizedType(
+                                java.util.Optional.class, newParameterizedType(Provider.class, type.getType())));
+    }
+
+    @SuppressWarnings("unchecked")
+    static <T> Key<Provider<T>> providerOf(Key<T> key) {
+        Type providerT = Types.providerOf(key.getTypeLiteral().getType());
+        return (Key<Provider<T>>) key.ofType(providerT);
+    }
+
+    enum Source {
+        DEFAULT,
+        ACTUAL
+    }
+
+    @Retention(RUNTIME)
+    @Qualifier
+    @interface Default {
+        String value();
+    }
+
+    @Retention(RUNTIME)
+    @Qualifier
+    @interface Actual {
+        String value();
+    }
+
+    private final BindingSelection<T> bindingSelection;
+    private final Binder binder;
+
+    private RealOptionalBinder(Binder binder, Key<T> typeKey) {
+        this.bindingSelection = new BindingSelection<>(typeKey);
+        this.binder = binder;
+    }
+
+    /**
+     * Adds a binding for T. Multiple calls to this are safe, and will be collapsed as duplicate
+     * bindings.
+     */
+    private void addDirectTypeBinding(Binder binder) {
+        binder
+                .bind(bindingSelection.getDirectKey())
+                .toProvider(new RealDirectTypeProvider<T>(bindingSelection));
+    }
+
+    /**
+     * Returns the key to use for the default binding.
+     *
+     * <p>As a side effect this installs support for the 'direct type', so a binding for {@code T}
+     * will be made available.
+     */
+    Key<T> getKeyForDefaultBinding() {
+        bindingSelection.checkNotInitialized();
+        addDirectTypeBinding(binder);
+        return bindingSelection.getKeyForDefaultBinding();
+    }
+
+    public LinkedBindingBuilder<T> setDefault() {
+        return binder.bind(getKeyForDefaultBinding());
+    }
+
+    /**
+     * Returns the key to use for the actual binding, overrides the default if set.
+     *
+     * <p>As a side effect this installs support for the 'direct type', so a binding for {@code T}
+     * will be made available.
+     */
+    Key<T> getKeyForActualBinding() {
+        bindingSelection.checkNotInitialized();
+        addDirectTypeBinding(binder);
+        return bindingSelection.getKeyForActualBinding();
+    }
+
+    public LinkedBindingBuilder<T> setBinding() {
+        return binder.bind(getKeyForActualBinding());
+    }
+
+    @Override
+    public void configure(Binder binder) {
+        bindingSelection.checkNotInitialized();
+        Key<T> key = bindingSelection.getDirectKey();
+        TypeLiteral<T> typeLiteral = key.getTypeLiteral();
+        // Every OptionalBinder gets the following types bound
+        // * {cgcb,ju}.Optional<Provider<T>>
+        // * {cgcb,ju}.Optional<javax.inject.Provider<T>>
+        // * {cgcb,ju}.Optional<T>
+        // If setDefault() or setBinding() is called then also
+        // * T is bound
+
+        // cgcb.Optional<Provider<T>>
+        InternalProviderInstanceBindingImpl.Factory<Optional<Provider<T>>> optionalProviderFactory =
+                new RealOptionalProviderProvider<>(bindingSelection);
+        binder.bind(key.ofType(optionalOfProvider(typeLiteral))).toProvider(optionalProviderFactory);
+        // ju.Optional<Provider<T>>
+        InternalProviderInstanceBindingImpl.Factory<java.util.Optional<Provider<T>>>
+                javaOptionalProviderFactory = new JavaOptionalProviderProvider<>(bindingSelection);
+        binder
+                .bind(key.ofType(javaOptionalOfProvider(typeLiteral)))
+                .toProvider(javaOptionalProviderFactory);
+
+        // Provider is assignable to javax.inject.Provider and the provider that the factory contains
+        // cannot be modified so we can use some rawtypes hackery to share the same implementation.
+
+        // cgcb.Optional<ji.Provider<T>>
+        @SuppressWarnings("unchecked")
+        InternalProviderInstanceBindingImpl.Factory<Optional<javax.inject.Provider<T>>>
+                optionalJavaxProviderFactory =
+                (InternalProviderInstanceBindingImpl.Factory) optionalProviderFactory;
+        binder
+                .bind(key.ofType(optionalOfJavaxProvider(typeLiteral)))
+                .toProvider(optionalJavaxProviderFactory);
+        // ju.Optional<ji.Provider<T>>
+        @SuppressWarnings("unchecked")
+        InternalProviderInstanceBindingImpl.Factory<java.util.Optional<javax.inject.Provider<T>>>
+                javaOptionalJavaxProviderFactory =
+                (InternalProviderInstanceBindingImpl.Factory) javaOptionalProviderFactory;
+        binder
+                .bind(key.ofType(javaOptionalOfJavaxProvider(typeLiteral)))
+                .toProvider(javaOptionalJavaxProviderFactory);
+
+        // cgcb.Optional<T>
+        Key<Optional<T>> optionalKey = key.ofType(optionalOf(typeLiteral));
+        binder
+                .bind(optionalKey)
+                .toProvider(new RealOptionalKeyProvider<>(bindingSelection, optionalKey));
+        // ju.Optional<T>
+        Key<java.util.Optional<T>> javaOptionalKey = key.ofType(javaOptionalOf(typeLiteral));
+        binder
+                .bind(javaOptionalKey)
+                .toProvider(new JavaOptionalProvider<>(bindingSelection, javaOptionalKey));
+    }
+
+    /** Provides the binding for java.util.Optional<T>. */
+    private static final class JavaOptionalProvider<T>
+            extends RealOptionalBinderProviderWithDependencies<T, java.util.Optional<T>>
+            implements ProviderWithExtensionVisitor<java.util.Optional<T>>,
+            OptionalBinderBinding<java.util.Optional<T>> {
+
+        private final Key<java.util.Optional<T>> optionalKey;
+
+        private Dependency<?> targetDependency;
+        private InternalFactory<? extends T> target;
+
+        JavaOptionalProvider(
+                BindingSelection<T> bindingSelection, Key<java.util.Optional<T>> optionalKey) {
+            super(bindingSelection);
+            this.optionalKey = optionalKey;
+        }
+
+        @Override
+        void doInitialize() {
+            if (bindingSelection.getBinding() != null) {
+                target = bindingSelection.getBinding().getInternalFactory();
+                targetDependency = bindingSelection.getDependency();
+            }
+        }
+
+        @Override
+        protected java.util.Optional<T> doProvision(
+                InternalContext context, Dependency<?> currentDependency)
+                throws InternalProvisionException {
+            InternalFactory<? extends T> local = target;
+            if (local == null) {
+                return java.util.Optional.empty();
+            }
+            Dependency<?> localDependency = targetDependency;
+            T result;
+            Dependency<?> previous = context.pushDependency(localDependency, getSource());
+            try {
+                // See comments in RealOptionalKeyProvider, about how localDependency may be more specific
+                // than what we actually need.
+                result = local.get(context, localDependency, false);
+            } catch (InternalProvisionException ipe) {
+                throw ipe.addSource(localDependency);
+            } finally {
+                context.popStateAndSetDependency(previous);
+
+            }
+            return java.util.Optional.ofNullable(result);
+        }
+
+        @Override
+        public Set<Dependency<?>> getDependencies() {
+            return bindingSelection.dependencies;
+        }
+
+        @SuppressWarnings("unchecked")
+        @Override
+        public <B, R> R acceptExtensionVisitor(
+                BindingTargetVisitor<B, R> visitor, ProviderInstanceBinding<? extends B> binding) {
+            if (visitor instanceof MultibindingsTargetVisitor) {
+                return ((MultibindingsTargetVisitor<java.util.Optional<T>, R>) visitor).visit(this);
+            } else {
+                return visitor.visit(binding);
+            }
+        }
+
+        @Override
+        public boolean containsElement(Element element) {
+            return bindingSelection.containsElement(element);
+        }
+
+        @Override
+        public Binding<?> getActualBinding() {
+            return bindingSelection.getActualBinding();
+        }
+
+        @Override
+        public Binding<?> getDefaultBinding() {
+            return bindingSelection.getDefaultBinding();
+        }
+
+        @Override
+        public Key<java.util.Optional<T>> getKey() {
+            return optionalKey;
+        }
+
+        @Override
+        public Set<Key<?>> getAlternateKeys() {
+            Key<?> key = bindingSelection.getDirectKey();
+            TypeLiteral<?> typeLiteral = key.getTypeLiteral();
+            return ImmutableSet.of(
+                    (Key<?>) key.ofType(javaOptionalOfProvider(typeLiteral)),
+                    (Key<?>) key.ofType(javaOptionalOfJavaxProvider(typeLiteral)));
+        }
+    }
+
+    /** Provides the binding for java.util.Optional<Provider<T>>. */
+    private static final class JavaOptionalProviderProvider<T>
+            extends RealOptionalBinderProviderWithDependencies<T, java.util.Optional<Provider<T>>> {
+        private java.util.Optional<Provider<T>> value;
+
+        JavaOptionalProviderProvider(BindingSelection<T> bindingSelection) {
+            super(bindingSelection);
+        }
+
+        @Override
+        void doInitialize() {
+            if (bindingSelection.getBinding() == null) {
+                value = java.util.Optional.empty();
+            } else {
+                value = java.util.Optional.of(bindingSelection.getBinding().getProvider());
+            }
+        }
+
+        @Override
+        protected java.util.Optional<Provider<T>> doProvision(
+                InternalContext context, Dependency<?> dependency) {
+            return value;
+        }
+
+        @Override
+        public Set<Dependency<?>> getDependencies() {
+            return bindingSelection.providerDependencies();
+        }
+    }
+
+    /** Provides the binding for T, conditionally installed by calling setBinding/setDefault. */
+    private static final class RealDirectTypeProvider<T>
+            extends RealOptionalBinderProviderWithDependencies<T, T> {
+        private Key<? extends T> targetKey;
+
+        private Object targetSource;
+
+        private InternalFactory<? extends T> targetFactory;
+
+        RealDirectTypeProvider(BindingSelection<T> bindingSelection) {
+            super(bindingSelection);
+        }
+
+        @Override
+        void doInitialize() {
+            BindingImpl<T> targetBinding = bindingSelection.getBinding();
+            // we only install this factory if they call setBinding()/setDefault() so we know that
+            // targetBinding will be non-null.
+            this.targetKey = targetBinding.getKey();
+            this.targetSource = targetBinding.getSource();
+            this.targetFactory = targetBinding.getInternalFactory();
+        }
+
+        @Override
+        protected T doProvision(InternalContext context, Dependency<?> dependency)
+                throws InternalProvisionException {
+            // This is what linked bindings do (see FactoryProxy), and we are pretty similar.
+            context.pushState(targetKey, targetSource);
+
+            try {
+                return targetFactory.get(context, dependency, true);
+            } catch (InternalProvisionException ipe) {
+                throw ipe.addSource(targetKey);
+            } finally {
+                context.popState();
+
+            }
+        }
+
+        @Override
+        public Set<Dependency<?>> getDependencies() {
+            return bindingSelection.dependencies;
+        }
+    }
+
+    /** Provides the binding for Optional<Provider<T>>. */
+    private static final class RealOptionalProviderProvider<T>
+            extends RealOptionalBinderProviderWithDependencies<T, Optional<Provider<T>>> {
+        private Optional<Provider<T>> value;
+
+        RealOptionalProviderProvider(BindingSelection<T> bindingSelection) {
+            super(bindingSelection);
+        }
+
+        @Override
+        void doInitialize() {
+            if (bindingSelection.getBinding() == null) {
+                value = Optional.absent();
+            } else {
+                value = Optional.of(bindingSelection.getBinding().getProvider());
+            }
+        }
+
+        @Override
+        protected Optional<Provider<T>> doProvision(InternalContext context, Dependency<?> dependency) {
+            return value;
+        }
+
+        @Override
+        public Set<Dependency<?>> getDependencies() {
+            return bindingSelection.providerDependencies();
+        }
+    }
+
+    /** Provides the binding for Optional<T>. */
+    private static final class RealOptionalKeyProvider<T>
+            extends RealOptionalBinderProviderWithDependencies<T, Optional<T>>
+            implements ProviderWithExtensionVisitor<Optional<T>>, OptionalBinderBinding<Optional<T>> {
+
+        private final Key<Optional<T>> optionalKey;
+
+        // These are assigned to non-null values during initialization if and only if we have a binding
+        // to delegate to.
+        private Dependency<?> targetDependency;
+        private InternalFactory<? extends T> delegate;
+
+        RealOptionalKeyProvider(BindingSelection<T> bindingSelection, Key<Optional<T>> optionalKey) {
+            super(bindingSelection);
+            this.optionalKey = optionalKey;
+        }
+
+        @Override
+        void doInitialize() {
+            if (bindingSelection.getBinding() != null) {
+                delegate = bindingSelection.getBinding().getInternalFactory();
+                targetDependency = bindingSelection.getDependency();
+            }
+        }
+
+        @Override
+        protected Optional<T> doProvision(InternalContext context, Dependency<?> currentDependency)
+                throws InternalProvisionException {
+            InternalFactory<? extends T> local = delegate;
+            if (local == null) {
+                return Optional.absent();
+            }
+            Dependency<?> localDependency = targetDependency;
+            T result;
+            Dependency<?> previous = context.pushDependency(localDependency, getSource());
+            try {
+                // currentDependency is Optional<? super T>, so we really just need to set the target
+                // dependency to ? super T, but we are currently setting it to T.  We could hypothetically
+                // make it easier for our delegate to generate proxies by modifying the dependency, but that
+                // would also require us to rewrite the key on each call.  So for now we don't do it.
+                result = local.get(context, localDependency, false);
+            } catch (InternalProvisionException ipe) {
+                throw ipe.addSource(localDependency);
+            } finally {
+                context.popStateAndSetDependency(previous);
+
+            }
+            return Optional.fromNullable(result);
+        }
+
+        @Override
+        public Set<Dependency<?>> getDependencies() {
+            return bindingSelection.dependencies();
+        }
+
+        @SuppressWarnings("unchecked")
+        @Override
+        public <B, R> R acceptExtensionVisitor(
+                BindingTargetVisitor<B, R> visitor, ProviderInstanceBinding<? extends B> binding) {
+            if (visitor instanceof MultibindingsTargetVisitor) {
+                return ((MultibindingsTargetVisitor<Optional<T>, R>) visitor).visit(this);
+            } else {
+                return visitor.visit(binding);
+            }
+        }
+
+        @Override
+        public Key<Optional<T>> getKey() {
+            return optionalKey;
+        }
+
+        @Override
+        public Set<Key<?>> getAlternateKeys() {
+            Key<?> key = bindingSelection.getDirectKey();
+            TypeLiteral<?> typeLiteral = key.getTypeLiteral();
+            return ImmutableSet.of(
+                    (Key<?>) key.ofType(optionalOfProvider(typeLiteral)),
+                    (Key<?>) key.ofType(optionalOfJavaxProvider(typeLiteral)));
+        }
+
+        @Override
+        public Binding<?> getActualBinding() {
+            return bindingSelection.getActualBinding();
+        }
+
+        @Override
+        public Binding<?> getDefaultBinding() {
+            return bindingSelection.getDefaultBinding();
+        }
+
+        @Override
+        public boolean containsElement(Element element) {
+            return bindingSelection.containsElement(element);
+        }
+    }
+
+    /**
+     * A helper object that implements the core logic for deciding what the implementation of the
+     * binding will be.
+     *
+     * <p>This also implements the main OptionalBinderBinding logic.
+     */
+    private static final class BindingSelection<T> {
+        private static final ImmutableSet<Dependency<?>> MODULE_DEPENDENCIES =
+                ImmutableSet.<Dependency<?>>of(Dependency.get(Key.get(Injector.class)));
+
+        /*@Nullable */ BindingImpl<T> actualBinding;
+        /*@Nullable */ BindingImpl<T> defaultBinding;
+        /*@Nullable */ BindingImpl<T> binding;
+        private boolean initialized;
+        private final Key<T> key;
+
+        // Until the injector initializes us, we don't know what our dependencies are,
+        // so initialize to the whole Injector (like Multibinder, and MapBinder indirectly).
+        private ImmutableSet<Dependency<?>> dependencies = MODULE_DEPENDENCIES;
+        private ImmutableSet<Dependency<?>> providerDependencies = MODULE_DEPENDENCIES;
+
+        /** lazily allocated, by {@link #getBindingName}. */
+        private String bindingName;
+
+        /** lazily allocated, by {@link #getKeyForDefaultBinding}. */
+        private Key<T> defaultBindingKey;
+
+        /** lazily allocated, by {@link #getKeyForActualBinding}. */
+        private Key<T> actualBindingKey;
+
+        BindingSelection(Key<T> key) {
+            this.key = key;
+        }
+
+        void checkNotInitialized() {
+            checkConfiguration(!initialized, "already initialized");
+        }
+
+        void initialize(InjectorImpl injector) {
+            // Every one of our providers will call this method, so only execute the logic once.
+            if (initialized) {
+                return;
+            }
+
+            actualBinding = injector.getExistingBinding(getKeyForActualBinding());
+            defaultBinding = injector.getExistingBinding(getKeyForDefaultBinding());
+            // We should never create Jit bindings, but we can use them if some other binding created it.
+            BindingImpl<T> userBinding = injector.getExistingBinding(key);
+            if (actualBinding != null) {
+                // TODO(sameb): Consider exposing an option that will allow
+                // ACTUAL to fallback to DEFAULT if ACTUAL's provider returns null.
+                // Right now, an ACTUAL binding can convert from present -> absent
+                // if it's bound to a provider that returns null.
+                binding = actualBinding;
+            } else if (defaultBinding != null) {
+                binding = defaultBinding;
+            } else if (userBinding != null) {
+                // If neither the actual or default is set, then we fallback
+                // to the value bound to the type itself and consider that the
+                // "actual binding" for the SPI.
+                binding = userBinding;
+                actualBinding = userBinding;
+            }
+            if (binding != null) {
+                dependencies = ImmutableSet.<Dependency<?>>of(Dependency.get(binding.getKey()));
+                providerDependencies =
+                        ImmutableSet.<Dependency<?>>of(Dependency.get(providerOf(binding.getKey())));
+            } else {
+                dependencies = ImmutableSet.of();
+                providerDependencies = ImmutableSet.of();
+            }
+            initialized = true;
+        }
+
+        Key<T> getKeyForDefaultBinding() {
+            if (defaultBindingKey == null) {
+                defaultBindingKey = Key.get(key.getTypeLiteral(), new DefaultImpl(getBindingName()));
+            }
+            return defaultBindingKey;
+        }
+
+        Key<T> getKeyForActualBinding() {
+            if (actualBindingKey == null) {
+                actualBindingKey = Key.get(key.getTypeLiteral(), new ActualImpl(getBindingName()));
+            }
+            return actualBindingKey;
+        }
+
+        Key<T> getDirectKey() {
+            return key;
+        }
+
+        private String getBindingName() {
+            // Lazily allocated, most instantiations will never need this because they are deduped during
+            // module installation.
+            if (bindingName == null) {
+                bindingName = Annotations.nameOf(key);
+            }
+            return bindingName;
+        }
+
+        BindingImpl<T> getBinding() {
+            return binding;
+        }
+
+        // Provide default implementations for most of the OptionalBinderBinding interface
+        BindingImpl<T> getDefaultBinding() {
+            return defaultBinding;
+        }
+
+        BindingImpl<T> getActualBinding() {
+            return actualBinding;
+        }
+
+        ImmutableSet<Dependency<?>> providerDependencies() {
+            return providerDependencies;
+        }
+
+        ImmutableSet<Dependency<?>> dependencies() {
+            return dependencies;
+        }
+
+        /**
+         * Returns the Dependency for the target binding, throws NoSuchElementException if no target
+         * exists.
+         *
+         * <p>Calls to this method should typically be guarded by checking if {@link #getBinding()}
+         * returns {@code null}.
+         */
+        Dependency<?> getDependency() {
+            return Iterables.getOnlyElement(dependencies);
+        }
+
+        /** Implementation of {@link OptionalBinderBinding#containsElement}. */
+        boolean containsElement(Element element) {
+            // All of our bindings are ProviderInstanceBindings whose providers extend
+            // RealOptionalBinderProviderWithDependencies and have 'this' as its binding selection.
+            if (element instanceof ProviderInstanceBinding) {
+                javax.inject.Provider<?> providerInstance =
+                        ((ProviderInstanceBinding<?>) element).getUserSuppliedProvider();
+                if (providerInstance instanceof RealOptionalBinderProviderWithDependencies) {
+                    return ((RealOptionalBinderProviderWithDependencies<?, ?>) providerInstance)
+                            .bindingSelection.equals(this);
+                }
+            }
+            if (element instanceof Binding) {
+                Key<?> elementKey = ((Binding) element).getKey();
+                // if it isn't one of the things we bound directly it might be an actual or default key
+                return elementKey.equals(getKeyForActualBinding())
+                        || elementKey.equals(getKeyForDefaultBinding());
+            }
+            return false; // cannot match;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            return o instanceof BindingSelection && ((BindingSelection) o).key.equals(key);
+        }
+
+        @Override
+        public int hashCode() {
+            return key.hashCode();
+        }
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        return o instanceof RealOptionalBinder
+                && ((RealOptionalBinder<?>) o).bindingSelection.equals(bindingSelection);
+    }
+
+    @Override
+    public int hashCode() {
+        return bindingSelection.hashCode();
+    }
+
+    /** A base class for ProviderWithDependencies that need equality based on a specific object. */
+    private abstract static class RealOptionalBinderProviderWithDependencies<T, P>
+            extends InternalProviderInstanceBindingImpl.Factory<P> {
+        protected final BindingSelection<T> bindingSelection;
+
+        RealOptionalBinderProviderWithDependencies(BindingSelection<T> bindingSelection) {
+            // We need delayed initialization so we can detect jit bindings created by other bindings
+            // while not also creating jit bindings ourselves.  This ensures we only pick up user bindings
+            // if the binding would have existed in the injector statically.
+            super(InitializationTiming.DELAYED);
+            this.bindingSelection = bindingSelection;
+        }
+
+        @Override
+        final void initialize(InjectorImpl injector, Errors errors) throws ErrorsException {
+            bindingSelection.initialize(injector);
+            doInitialize();
+        }
+
+        /**
+         * Initialize the factory. BindingSelection is guaranteed to be initialized at this point and
+         * this will be called prior to any provisioning.
+         */
+        abstract void doInitialize();
+
+        @Override
+        public boolean equals(Object obj) {
+            return obj != null
+                    && this.getClass() == obj.getClass()
+                    && bindingSelection.equals(
+                    ((RealOptionalBinderProviderWithDependencies<?, ?>) obj).bindingSelection);
+        }
+
+        @Override
+        public int hashCode() {
+            return bindingSelection.hashCode();
+        }
+    }
+
+    @SuppressWarnings("serial")
+    static class DefaultImpl extends BaseAnnotation implements Default {
+        public DefaultImpl(String value) {
+            super(Default.class, value);
+        }
+    }
+
+    @SuppressWarnings("serial")
+    static class ActualImpl extends BaseAnnotation implements Actual {
+        public ActualImpl(String value) {
+            super(Actual.class, value);
+        }
+    }
+
+    abstract static class BaseAnnotation implements Serializable, Annotation {
+
+        private final String value;
+        private final Class<? extends Annotation> clazz;
+
+        BaseAnnotation(Class<? extends Annotation> clazz, String value) {
+            this.clazz = checkNotNull(clazz, "clazz");
+            this.value = checkNotNull(value, "value");
+        }
+
+        public String value() {
+            return this.value;
+        }
+
+        @Override
+        public int hashCode() {
+            // This is specified in java.lang.Annotation.
+            return (127 * "value".hashCode()) ^ value.hashCode();
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            // We check against each annotation type instead of BaseAnnotation
+            // so that we can compare against generated annotation implementations.
+            if (o instanceof Actual && clazz == Actual.class) {
+                Actual other = (Actual) o;
+                return value.equals(other.value());
+            } else if (o instanceof Default && clazz == Default.class) {
+                Default other = (Default) o;
+                return value.equals(other.value());
+            }
+            return false;
+        }
+
+        @Override
+        public String toString() {
+            return "@" + clazz.getName() + (value.isEmpty() ? "" : "(value=" + value + ")");
+        }
+
+        @Override
+        public Class<? extends Annotation> annotationType() {
+            return clazz;
+        }
+
+        private static final long serialVersionUID = 0;
+    }
+}

src/main/java/com/google/inject/internal/Scoping.java

@@ -184,8 +184,7 @@ public abstract class Scoping {
 
         Scope scope = scoping.getScopeInstance();
 
-        Provider<T> scoped
+        Provider<T> scoped = scope.scope(key, new ProviderToInternalFactoryAdapter<T>(injector, creator));
-                = scope.scope(key, new ProviderToInternalFactoryAdapter<T>(injector, creator));
         return new InternalFactoryToProviderAdapter<T>(scoped, source);
     }
 

src/main/java/com/google/inject/internal/SingleFieldInjector.java

@@ -10,35 +10,38 @@ import java.lang.reflect.Field;
  * Sets an injectable field.
  */
 final class SingleFieldInjector implements SingleMemberInjector {
-    final Field field;
-    final InjectionPoint injectionPoint;
-    final Dependency<?> dependency;
-    final BindingImpl<?> binding;
 
-    public SingleFieldInjector(InjectorImpl injector, InjectionPoint injectionPoint, Errors errors)
+    private final Field field;
+
+    private final InjectionPoint injectionPoint;
+
+    private final Dependency<?> dependency;
+
+    private final BindingImpl<?> binding;
+
+    SingleFieldInjector(InjectorImpl injector, InjectionPoint injectionPoint, Errors errors)
             throws ErrorsException {
         this.injectionPoint = injectionPoint;
         this.field = (Field) injectionPoint.getMember();
         this.dependency = injectionPoint.getDependencies().get(0);
-
         // Ewwwww...
         field.setAccessible(true);
         binding = injector.getBindingOrThrow(dependency.getKey(), errors, JitLimitation.NO_JIT);
     }
 
+    @Override
     public InjectionPoint getInjectionPoint() {
         return injectionPoint;
     }
 
-    public void inject(Errors errors, InternalContext context, Object o) {
+    @Override
-        errors = errors.withSource(dependency);
+    public void inject(InternalContext context, Object o) throws InternalProvisionException {
-
+        Dependency<?> previous = context.pushDependency(dependency, binding.getSource());
-        Dependency previous = context.pushDependency(dependency, binding.getSource());
         try {
-            Object value = binding.getInternalFactory().get(errors, context, dependency, false);
+            Object value = binding.getInternalFactory().get(context, dependency, false);
             field.set(o, value);
-        } catch (ErrorsException e) {
+        } catch (InternalProvisionException e) {
-            errors.withSource(injectionPoint).merge(e.getErrors());
+            throw e.addSource(dependency);
         } catch (IllegalAccessException e) {
             throw new AssertionError(e); // a security manager is blocking us, we're hosed
         } finally {

src/main/java/com/google/inject/internal/SingleMemberInjector.java

@@ -6,7 +6,7 @@ import com.google.inject.spi.InjectionPoint;
  * Injects a field or method of a given object.
  */
 interface SingleMemberInjector {
-    void inject(Errors errors, InternalContext context, Object o);
+    void inject(InternalContext context, Object o) throws InternalProvisionException;
 
     InjectionPoint getInjectionPoint();
 }

src/main/java/com/google/inject/internal/SingleMethodInjector.java

@@ -29,37 +29,23 @@ final class SingleMethodInjector implements SingleMemberInjector {
                 !Modifier.isPublic(method.getDeclaringClass().getModifiers())) {
             method.setAccessible(true);
         }
-
+        return method::invoke;
-        return new MethodInvoker() {
-            public Object invoke(Object target, Object... parameters)
-                    throws IllegalAccessException, InvocationTargetException {
-                return method.invoke(target, parameters);
-            }
-        };
     }
 
     public InjectionPoint getInjectionPoint() {
         return injectionPoint;
     }
 
-    public void inject(Errors errors, InternalContext context, Object o) {
+    @Override
-        Object[] parameters;
+    public void inject(InternalContext context, Object o) throws InternalProvisionException {
-        try {
+        Object[] parameters = SingleParameterInjector.getAll(context, parameterInjectors);
-            parameters = SingleParameterInjector.getAll(errors, context, parameterInjectors);
-        } catch (ErrorsException e) {
-            errors.merge(e.getErrors());
-            return;
-        }
-
         try {
             methodInvoker.invoke(o, parameters);
         } catch (IllegalAccessException e) {
             throw new AssertionError(e); // a security manager is blocking us, we're hosed
         } catch (InvocationTargetException userException) {
-            Throwable cause = userException.getCause() != null
+            Throwable cause = userException.getCause() != null ? userException.getCause() : userException;
-                    ? userException.getCause()
+            throw InternalProvisionException.errorInjectingMethod(cause).addSource(injectionPoint);
-                    : userException;
-            errors.withSource(injectionPoint).errorInjectingMethod(cause);
         }
     }
 }

src/main/java/com/google/inject/internal/SingleParameterInjector.java

@@ -6,48 +6,47 @@ import com.google.inject.spi.Dependency;
  * Resolves a single parameter, to be used in a constructor or method invocation.
  */
 final class SingleParameterInjector<T> {
+
     private static final Object[] NO_ARGUMENTS = {};
 
     private final Dependency<T> dependency;
-    private final BindingImpl<? extends T> binding;
+
+    private final Object source;
+
+    private final InternalFactory<? extends T> factory;
 
     SingleParameterInjector(Dependency<T> dependency, BindingImpl<? extends T> binding) {
         this.dependency = dependency;
-        this.binding = binding;
+        this.source = binding.getSource();
+        this.factory = binding.getInternalFactory();
     }
 
     /**
      * Returns an array of parameter values.
      */
-    static Object[] getAll(Errors errors, InternalContext context,
+    static Object[] getAll(InternalContext context,
-                           SingleParameterInjector<?>[] parameterInjectors) throws ErrorsException {
+                           SingleParameterInjector<?>[] parameterInjectors) throws InternalProvisionException {
         if (parameterInjectors == null) {
             return NO_ARGUMENTS;
         }
-
-        int numErrorsBefore = errors.size();
-
         int size = parameterInjectors.length;
         Object[] parameters = new Object[size];
 
         // optimization: use manual for/each to save allocating an iterator here
         for (int i = 0; i < size; i++) {
-            SingleParameterInjector<?> parameterInjector = parameterInjectors[i];
+            parameters[i] = parameterInjectors[i].inject(context);
-            try {
-                parameters[i] = parameterInjector.inject(errors, context);
-            } catch (ErrorsException e) {
-                errors.merge(e.getErrors());
         }
-        }
-
-        errors.throwIfNewErrors(numErrorsBefore);
         return parameters;
     }
 
-    private T inject(Errors errors, InternalContext context) throws ErrorsException {
+    T inject(InternalContext context) throws InternalProvisionException {
-        Dependency previous = context.pushDependency(dependency, binding.getSource());
+        Dependency<T> localDependency = dependency;
+        Dependency<?> previous = context.pushDependency(localDependency, source);
+
         try {
-            return binding.getInternalFactory().get(errors.withSource(dependency), context, dependency, false);
+            return factory.get(context, localDependency, false);
+        } catch (InternalProvisionException ipe) {
+            throw ipe.addSource(localDependency);
         } finally {
             context.popStateAndSetDependency(previous);
         }