Fix memory leak related to ActionBar

Author: t0maboro

android/src/main/java/com/swmansion/rnscreens/ScreenStackFragment.kt

@@ -14,6 +14,8 @@ import android.view.View
 import android.view.ViewGroup
 import android.view.animation.Animation
 import android.widget.LinearLayout
+import androidx.appcompat.app.ActionBar
+import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.widget.Toolbar
 import androidx.coordinatorlayout.widget.CoordinatorLayout
 import androidx.core.view.ViewCompat
@@ -57,6 +59,8 @@ class ScreenStackFragment :
     private var isToolbarShadowHidden = false
     private var isToolbarTranslucent = false
 
+    private var ownedActionBar: ActionBar? = null
+
     private lateinit var sheetTransitionCoordinator: BottomSheetTransitionCoordinator
 
     private var lastFocusedChild: View? = null
@@ -301,6 +305,37 @@ class ScreenStackFragment :
         super.onViewCreated(view, savedInstanceState)
     }
 
+    internal fun onActionBarSet(actionBar: ActionBar) {
+        ownedActionBar = actionBar
+    }
+
+    override fun onDestroyView() {
+        // ScreenStackHeaderConfig.onUpdate() calls activity.setSupportActionBar(toolbar) each time
+        // the top screen updates. AppCompatDelegateImpl stores the resulting ToolbarActionBar in
+        // its mActionBar field for the lifetime of the activity. When a screen is popped and the new
+        // top screen does not install a replacement action bar (e.g. headerShown: false),
+        // the stale ToolbarActionBar — and the entire object graph hanging off the toolbar is never released.
+        // When this fragment is being removed, we're clearing the activity's support action bar if it
+        // still belongs to us. This will break the retention chain:
+        // - AppCompatDelegateImpl.mActionBar
+        // - ToolbarActionBar.mDecorToolbar
+        // - ToolbarWidgetWrapper.mToolbar
+        // - DebugMenuToolbar.config
+        // - ScreenStackHeaderConfig.mParent
+        // - Screen.fragment
+        if (isRemoving) {
+            ownedActionBar?.let { owned ->
+                (activity as? AppCompatActivity)?.let { appCompat ->
+                    if (appCompat.supportActionBar === owned) {
+                        appCompat.setSupportActionBar(null)
+                    }
+                }
+            }
+            ownedActionBar = null
+        }
+        super.onDestroyView()
+    }
+
     override fun onCreateAnimation(
         transit: Int,
         enter: Boolean,

android/src/main/java/com/swmansion/rnscreens/ScreenStackHeaderConfig.kt

@@ -244,6 +244,8 @@ class ScreenStackHeaderConfig(
         activity.setSupportActionBar(toolbar)
         // non-null toolbar is set in the line above and it is used here
         val actionBar = requireNotNull(activity.supportActionBar)
+        // notify the fragment so it can clear this action bar reference when being removed.
+        screenFragment?.onActionBarSet(actionBar)
 
         // hide back button
         actionBar.setDisplayHomeAsUpEnabled(

apps/src/tests/issue-tests/TestXXXX.tsx

@@ -0,0 +1,97 @@
+import React from 'react';
+import { View, Text, Button, StyleSheet } from 'react-native';
+import { NavigationContainer, ParamListBase } from '@react-navigation/native';
+import {
+  createNativeStackNavigator,
+  NativeStackNavigationProp,
+} from '@react-navigation/native-stack';
+
+type RouteParamList = {
+  Home: undefined;
+  Details: undefined;
+  Settings: undefined;
+};
+
+type NavigationProp<ParamList extends ParamListBase> = {
+  navigation: NativeStackNavigationProp<ParamList>;
+};
+
+type StackNavigationProp = NavigationProp<RouteParamList>;
+
+const Stack = createNativeStackNavigator<RouteParamList>();
+
+function HomeScreen({ navigation }: StackNavigationProp) {
+  return (
+    <View style={styles.container}>
+      <Text style={styles.title}>Home Screen</Text>
+      <Button
+        title="Push Details"
+        onPress={() => navigation.navigate('Details')}
+      />
+    </View>
+  );
+}
+
+function DetailScreen({ navigation }: StackNavigationProp) {
+  return (
+    <View style={styles.container}>
+      <Text style={styles.title}>Details Screen</Text>
+      <Button
+        title="Push Settings"
+        onPress={() => navigation.navigate('Settings')}
+      />
+      <View style={styles.spacer} />
+      <Button
+        title="Pop (Go Back)"
+        onPress={() => navigation.goBack()}
+        color="red"
+      />
+    </View>
+  );
+}
+
+function DeepDetailScreen({ navigation }: StackNavigationProp) {
+  return (
+    <View style={styles.container}>
+      <Text style={styles.title}>Settings Screen</Text>
+      <View style={styles.spacer} />
+      <Button
+        title="Pop to Top"
+        onPress={() => navigation.popToTop()}
+        color="red"
+      />
+    </View>
+  );
+}
+
+export default function App() {
+  return (
+    <NavigationContainer>
+      <Stack.Navigator>
+        <Stack.Screen
+          name="Home"
+          component={HomeScreen}
+          options={{ headerShown: false }}
+        />
+        <Stack.Screen name="Details" component={DetailScreen} />
+        <Stack.Screen name="Settings" component={DeepDetailScreen} />
+      </Stack.Navigator>
+    </NavigationContainer>
+  );
+}
+
+const styles = StyleSheet.create({
+  container: {
+    flex: 1,
+    alignItems: 'center',
+    justifyContent: 'center',
+  },
+  title: {
+    fontSize: 20,
+    fontWeight: 'bold',
+    marginBottom: 10,
+  },
+  spacer: {
+    height: 20,
+  },
+});

apps/src/tests/issue-tests/index.ts

@@ -187,6 +187,7 @@ export { default as Test3770 } from './Test3770';
 export { default as Test3793 } from './Test3793';
 export { default as Test3816 } from './Test3816';
 export { default as Test3833 } from './Test3833';
+export { default as TestXXXX } from './TestXXXX';
 export { default as TestScreenAnimation } from './TestScreenAnimation';
 // The following test was meant to demo the "go back" gesture using Reanimated
 // but the associated PR in react-navigation is currently put on hold