Clears Fragment reference in FragmentContextWrapper after Fragment#onDestroy()

java/dagger/android/support/BUILD

@@ -45,6 +45,7 @@ android_library(
         "@maven//:androidx_annotation_annotation",
         "@maven//:androidx_appcompat_appcompat",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
     ],

java/dagger/hilt/android/BUILD

@@ -44,6 +44,7 @@ android_library(
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_annotation_annotation",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
     ],
@@ -82,6 +83,7 @@ android_library(
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_annotation_annotation",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
     ],
@@ -100,6 +102,7 @@ android_library(
         "@google_bazel_common//third_party/java/jsr305_annotations",
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
     ],
@@ -196,6 +199,7 @@ gen_maven_artifact(
         "androidx.activity:activity",
         "androidx.annotation:annotation",
         "androidx.fragment:fragment",
+        "androidx.lifecycle:lifecycle-common",
         "androidx.lifecycle:lifecycle-viewmodel",
         "androidx.lifecycle:lifecycle-viewmodel-savedstate",
         "androidx.savedstate:savedstate",

java/dagger/hilt/android/internal/builders/BUILD

@@ -27,6 +27,7 @@ android_library(
         "//java/dagger/hilt/android/components:view_model_component",
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
     ],

java/dagger/hilt/android/internal/lifecycle/BUILD

@@ -31,6 +31,7 @@ android_library(
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_annotation_annotation",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
         "@maven//:androidx_savedstate_savedstate",

java/dagger/hilt/android/internal/managers/BUILD

@@ -50,6 +50,7 @@ android_library(
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_annotation_annotation",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
     ],

java/dagger/hilt/android/internal/managers/ViewComponentManager.java

@@ -16,6 +16,9 @@
 
 package dagger.hilt.android.internal.managers;
 
+import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.LifecycleEventObserver;
+import androidx.lifecycle.LifecycleOwner;
 import android.content.Context;
 import android.content.ContextWrapper;
 import androidx.fragment.app.Fragment;
@@ -104,7 +107,7 @@ private GeneratedComponentManager<?> getParentComponentManager(boolean allowMiss
       if (context instanceof FragmentContextWrapper) {
 
         FragmentContextWrapper fragmentContextWrapper = (FragmentContextWrapper) context;
-        return (GeneratedComponentManager<?>) fragmentContextWrapper.fragment;
+        return (GeneratedComponentManager<?>) fragmentContextWrapper.getFragment();
       } else if (allowMissing) {
         // We didn't find anything, so return null if we're not supposed to fail.
         // The rest of the logic is just about getting a good error message.
@@ -167,20 +170,38 @@ private static Context unwrap(Context context, Class<?> target) {
    */
   // This is only non-final for the account override
   public static final class FragmentContextWrapper extends ContextWrapper {
+    private Fragment fragment;
     private LayoutInflater baseInflater;
     private LayoutInflater inflater;
-    public final Fragment fragment;
-
-    public FragmentContextWrapper(Context base, Fragment fragment) {
+    private final LifecycleEventObserver fragmentLifecycleObserver =
+        new LifecycleEventObserver() {
+          @Override
+          public void onStateChanged(LifecycleOwner source, Lifecycle.Event event) {
+            if (event == Lifecycle.Event.ON_DESTROY) {
+              // Prevent the fragment from leaking if the view outlives the fragment.
+              // See https://github.com/google/dagger/issues/2070
+              FragmentContextWrapper.this.fragment = null;
+            }
+          }
+        };
+
+    FragmentContextWrapper(Context base, Fragment fragment) {
       super(Preconditions.checkNotNull(base));
       this.baseInflater = null;
       this.fragment = Preconditions.checkNotNull(fragment);
+      this.fragment.getLifecycle().addObserver(fragmentLifecycleObserver);
     }
 
-    public FragmentContextWrapper(LayoutInflater baseInflater, Fragment fragment) {
+    FragmentContextWrapper(LayoutInflater baseInflater, Fragment fragment) {
       super(Preconditions.checkNotNull(Preconditions.checkNotNull(baseInflater).getContext()));
       this.baseInflater = baseInflater;
       this.fragment = Preconditions.checkNotNull(fragment);
+      this.fragment.getLifecycle().addObserver(fragmentLifecycleObserver);
+    }
+
+    Fragment getFragment() {
+      Preconditions.checkNotNull(fragment, "The fragment has already been destroyed.");
+      return fragment;
     }
 
     @Override

java/dagger/hilt/android/internal/modules/BUILD

@@ -28,6 +28,7 @@ android_library(
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_annotation_annotation",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
     ],

java/dagger/hilt/android/migration/BUILD

@@ -33,6 +33,7 @@ android_library(
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_annotation_annotation",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
     ],

java/dagger/hilt/android/testing/BUILD

@@ -212,6 +212,7 @@ gen_maven_artifact(
         "androidx.activity:activity",
         "androidx.annotation:annotation",
         "androidx.fragment:fragment",
+        "androidx.lifecycle:lifecycle-common",
         "androidx.lifecycle:lifecycle-viewmodel",
         "androidx.lifecycle:lifecycle-viewmodel-savedstate",
         "androidx.multidex:multidex",

javatests/dagger/android/processor/BUILD

@@ -38,6 +38,7 @@ GenJavaTests(
         "@google_bazel_common//third_party/java/truth",
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
     ],

javatests/dagger/android/support/BUILD

@@ -40,6 +40,7 @@ GenRobolectricTests(
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_appcompat_appcompat",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
     ],

javatests/dagger/android/support/functional/BUILD

@@ -31,6 +31,7 @@ android_library(
     deps = [
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
         "@maven//:androidx_appcompat_appcompat",
@@ -57,6 +58,7 @@ GenRobolectricTests(
         "@google_bazel_common//third_party/java/truth",
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
         "@maven//:androidx_test_core",

javatests/dagger/hilt/android/BUILD

@@ -298,6 +298,7 @@ android_local_test(
         "@google_bazel_common//third_party/java/truth",
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
         "@maven//:junit_junit",
@@ -322,6 +323,7 @@ android_local_test(
         "@google_bazel_common//third_party/java/truth",
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
         "@maven//:junit_junit",
@@ -358,6 +360,7 @@ android_local_test(
         "@google_bazel_common//third_party/java/truth",
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
         "@maven//:junit_junit",
@@ -383,6 +386,7 @@ android_local_test(
         "@google_bazel_common//third_party/java/truth",
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
         "@maven//:junit_junit",
@@ -410,6 +414,7 @@ android_local_test(
         "@google_bazel_common//third_party/java/truth",
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
         "@maven//:junit_junit",
@@ -436,6 +441,7 @@ android_local_test(
         "@google_bazel_common//third_party/java/truth",
         "@maven//:androidx_activity_activity",
         "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel",
         "@maven//:androidx_lifecycle_lifecycle_viewmodel_savedstate",
         "@maven//:junit_junit",

javatests/dagger/hilt/android/internal/managers/AndroidManifest.xml

@@ -0,0 +1,11 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="dagger.hilt.android.internal.managers">
+
+  <uses-sdk android:minSdkVersion="14" />
+
+  <application>
+    <activity
+        android:name=".FragmentContextWrapperLeakTest$TestActivity"
+        android:exported="false"/>
+  </application>
+</manifest>

javatests/dagger/hilt/android/internal/managers/BUILD

@@ -0,0 +1,39 @@
+# Copyright (C) 2021 The Dagger 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
+#
+# http://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.
+# Description:
+#   Tests for internal code for implementing Hilt processors.
+
+package(default_visibility = ["//:src"])
+
+android_local_test(
+    name = "FragmentContextWrapperLeakTest",
+    size = "small",
+    srcs = ["FragmentContextWrapperLeakTest.java"],
+    manifest = "AndroidManifest.xml",
+    manifest_values = {
+        "minSdkVersion": "14",
+    },
+    deps = [
+        "//:android_local_test_exports",
+        "//:dagger_with_compiler",
+        "@google_bazel_common//third_party/java/jsr330_inject",
+        "@maven//:junit_junit",
+        "@google_bazel_common//third_party/java/truth",
+        "//java/dagger/hilt:entry_point",
+        "//java/dagger/hilt:install_in",
+        "//java/dagger/hilt/android:android_entry_point",
+        "//java/dagger/hilt/android/lifecycle",
+        "//java/dagger/hilt/android/testing:hilt_android_test",
+    ],
+)

javatests/dagger/hilt/android/internal/managers/FragmentContextWrapperLeakTest.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2021 The Dagger 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
+ *
+ * http://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.
+ */
+
+package dagger.hilt.android.internal.managers;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import androidx.lifecycle.Lifecycle;
+import android.os.Build;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentActivity;
+import androidx.test.core.app.ActivityScenario;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import dagger.hilt.android.AndroidEntryPoint;
+import dagger.hilt.android.internal.managers.ViewComponentManager.FragmentContextWrapper;
+import dagger.hilt.android.testing.HiltAndroidRule;
+import dagger.hilt.android.testing.HiltAndroidTest;
+import dagger.hilt.android.testing.HiltTestApplication;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.annotation.Config;
+
+@HiltAndroidTest
+@RunWith(AndroidJUnit4.class)
+// Robolectric requires Java9 to run API 29 and above, so use API 28 instead
+@Config(sdk = Build.VERSION_CODES.P, application = HiltTestApplication.class)
+public final class FragmentContextWrapperLeakTest {
+  /** An activity to test injection. */
+  @AndroidEntryPoint(FragmentActivity.class)
+  public static final class TestActivity extends Hilt_FragmentContextWrapperLeakTest_TestActivity {}
+
+  /** A fragment to test injection. */
+  @AndroidEntryPoint(Fragment.class)
+  public static final class TestFragment extends Hilt_FragmentContextWrapperLeakTest_TestFragment {}
+
+  @Rule public HiltAndroidRule hiltRule = new HiltAndroidRule(this);
+
+  @Test
+  public void testFragmentContextWrapperDoesNotLeakFragment() {
+    try (ActivityScenario<TestActivity> scenario = ActivityScenario.launch(TestActivity.class)) {
+      TestFragment fragment = new TestFragment();
+      scenario.onActivity(
+          activity ->
+              activity
+                  .getSupportFragmentManager()
+                  .beginTransaction()
+                  .add(fragment, "TestFragment")
+                  .commitNow());
+
+      FragmentContextWrapper fragmentContextWrapper =
+          (FragmentContextWrapper) fragment.getContext();
+      assertThat(fragmentContextWrapper.getFragment()).isEqualTo(fragment);
+      scenario.moveToState(Lifecycle.State.DESTROYED);
+      NullPointerException exception =
+          assertThrows(NullPointerException.class, fragmentContextWrapper::getFragment);
+      assertThat(exception).hasMessageThat().contains("The fragment has already been destroyed");
+    }
+  }
+}