How to keep some com.google.android.play.core.* classes reported missing by R8 during a release build of a Flutter app?

Question

When I build an APK it comes out to be 30MB. I recently upgraded to AGP 8.1 from 7.4, not sure if that screwed up something. The Task :app:minifyReleaseWithR8 FAILED fails. The short message is:

Missing classes detected while running R8. Please add the missing classes or apply additional keep rules that are generated in /home/csaba/repos/flutter/track_my_indoor_exercise/build/app/outputs/mapping/release/missing_rules.txt.

The referenced file contains:

# Please add these rules to your existing keep rules in order to suppress warnings.
# This is generated automatically by the Android Gradle plugin.
-dontwarn com.google.android.play.core.splitcompat.SplitCompatApplication
-dontwarn com.google.android.play.core.splitinstall.SplitInstallException
-dontwarn com.google.android.play.core.splitinstall.SplitInstallManager
-dontwarn com.google.android.play.core.splitinstall.SplitInstallManagerFactory
-dontwarn com.google.android.play.core.splitinstall.SplitInstallRequest$Builder
-dontwarn com.google.android.play.core.splitinstall.SplitInstallRequest
-dontwarn com.google.android.play.core.splitinstall.SplitInstallSessionState
-dontwarn com.google.android.play.core.splitinstall.SplitInstallStateUpdatedListener
-dontwarn com.google.android.play.core.tasks.OnFailureListener
-dontwarn com.google.android.play.core.tasks.OnSuccessListener
-dontwarn com.google.android.play.core.tasks.Task

I tried to add

-keep class com.google.android.play.core.splitcompat.** { *; }
-keepclassmembernames class com.google.android.play.core.splitcompat.** { *; }
-keepclassmembers class com.google.android.play.core.splitcompat.** { *; }
-keep class com.google.android.play.core.splitinstall.** { *; }
-keepclassmembernames class com.google.android.play.core.splitinstall.** { *; }
-keepclassmembers class com.google.android.play.core.splitinstall.** { *; }
-keep class com.google.android.play.core.tasks.** { *; }
-keepclassmembernames class com.google.android.play.core.tasks.** { *; }
-keepclassmembers class com.google.android.play.core.tasks.** { *; }

into my ProGuard, and then even tried to add

-keep class com.google.android.play.core.splitcompat.SplitCompatApplication
-keep class com.google.android.play.core.splitinstall.SplitInstallException
-keep class com.google.android.play.core.splitinstall.SplitInstallManager
-keep class com.google.android.play.core.splitinstall.SplitInstallManagerFactory
-keep class com.google.android.play.core.splitinstall.SplitInstallRequest$Builder
-keep class com.google.android.play.core.splitinstall.SplitInstallRequest
-keep class com.google.android.play.core.splitinstall.SplitInstallSessionState
-keep class com.google.android.play.core.splitinstall.SplitInstallStateUpdatedListener
-keep class com.google.android.play.core.tasks.OnFailureListener
-keep class com.google.android.play.core.tasks.OnSuccessListener
-keep class com.google.android.play.core.tasks.Task

But the same classes reported missing still. It's like the ProGuard file is ignored or something.

The longer task error:

> Task :app:minifyReleaseWithR8 FAILED
AGPBI: {"kind":"error","text":"Missing classes detected while running R8. Please add the missing classes or apply additional keep rules that are generated in /home/csaba/repos/flutter/track_my_indoor_exercise/build/app/outputs/mapping/release/missing_rules.txt.","sources":[{}]}
AGPBI: {"kind":"error","text":"Missing class com.google.android.play.core.splitcompat.SplitCompatApplication (referenced from: void io.flutter.app.FlutterPlayStoreSplitApplication.<init>() and 5 other contexts)\nMissing class com.google.android.play.core.splitinstall.SplitInstallException (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.lambda$installDeferredComponent$1(int, java.lang.String, java.lang.Exception))\nMissing class com.google.android.play.core.splitinstall.SplitInstallManager (referenced from: com.google.android.play.core.splitinstall.SplitInstallManager io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.splitInstallManager and 5 other contexts)\nMissing class com.google.android.play.core.splitinstall.SplitInstallManagerFactory (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.<init>(android.content.Context, io.flutter.embedding.engine.FlutterJNI))\nMissing class com.google.android.play.core.splitinstall.SplitInstallRequest$Builder (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.installDeferredComponent(int, java.lang.String))\nMissing class com.google.android.play.core.splitinstall.SplitInstallRequest (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.installDeferredComponent(int, java.lang.String))\nMissing class com.google.android.play.core.splitinstall.SplitInstallSessionState (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager$FeatureInstallStateUpdatedListener.onStateUpdate(com.google.android.play.core.splitinstall.SplitInstallSessionState) and 1 other context)\nMissing class com.google.android.play.core.splitinstall.SplitInstallStateUpdatedListener (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.<init>(android.content.Context, io.flutter.embedding.engine.FlutterJNI) and 2 other contexts)\nMissing class com.google.android.play.core.tasks.OnFailureListener (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.installDeferredComponent(int, java.lang.String))\nMissing class com.google.android.play.core.tasks.OnSuccessListener (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.installDeferredComponent(int, java.lang.String))\nMissing class com.google.android.play.core.tasks.Task (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.installDeferredComponent(int, java.lang.String) and 1 other context)","sources":[{}],"tool":"R8"}
Missing classes detected while running R8. Please add the missing classes or apply additional keep rules that are generated in /home/csaba/repos/flutter/track_my_indoor_exercise/build/app/outputs/mapping/release/missing_rules.txt.

Missing class com.google.android.play.core.splitcompat.SplitCompatApplication (referenced from: void io.flutter.app.FlutterPlayStoreSplitApplication.<init>() and 5 other contexts)
Missing class com.google.android.play.core.splitinstall.SplitInstallException (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.lambda$installDeferredComponent$1(int, java.lang.String, java.lang.Exception))
Missing class com.google.android.play.core.splitinstall.SplitInstallManager (referenced from: com.google.android.play.core.splitinstall.SplitInstallManager io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.splitInstallManager and 5 other contexts)
Missing class com.google.android.play.core.splitinstall.SplitInstallManagerFactory (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.<init>(android.content.Context, io.flutter.embedding.engine.FlutterJNI))
Missing class com.google.android.play.core.splitinstall.SplitInstallRequest$Builder (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.installDeferredComponent(int, java.lang.String))
Missing class com.google.android.play.core.splitinstall.SplitInstallRequest (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.installDeferredComponent(int, java.lang.String))
Missing class com.google.android.play.core.splitinstall.SplitInstallSessionState (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager$FeatureInstallStateUpdatedListener.onStateUpdate(com.google.android.play.core.splitinstall.SplitInstallSessionState) and 1 other context)
Missing class com.google.android.play.core.splitinstall.SplitInstallStateUpdatedListener (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.<init>(android.content.Context, io.flutter.embedding.engine.FlutterJNI) and 2 other contexts)
Missing class com.google.android.play.core.tasks.OnFailureListener (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.installDeferredComponent(int, java.lang.String))
Missing class com.google.android.play.core.tasks.OnSuccessListener (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.installDeferredComponent(int, java.lang.String))
Missing class com.google.android.play.core.tasks.Task (referenced from: void io.flutter.embedding.engine.deferredcomponents.PlayStoreDeferredComponentManager.installDeferredComponent(int, java.lang.String) and 1 other context)

The rules file at the time of the error: https://github.com/TrackMyIndoorWorkout/TrackMyIndoorWorkout/blob/11d7bc8a1a6407dfe257ccbe6a68ac531c36719e/android/app/proguard-rules.pro

Answer 1

This turns out to be really Flutter related. I haven't disclosed my whole proguard rules because it's kind of long: I have rules for every Flutter plugin to avoid MissingPluginExceptions (see https://csaba.page/blog/the-dreaded-missing-plugin-exception.html and rules I use https://csaba.page/blog/flutter-android-crash-remedies.html). The full rules file looks like this: https://github.com/TrackMyIndoorWorkout/TrackMyIndoorWorkout/blob/11d7bc8a1a6407dfe257ccbe6a68ac531c36719e/android/app/proguard-rules.pro

I took a second look at the longer (detailed) task error. I noted the referenced from: sections: referenced from io.flutter.app..., io.flutter.embedding.engine.... I noticed that I have some rules about those because at some point in the past I treated a Flutter issue: https://github.com/flutter/flutter/issues/78625#issuecomment-804164524

I commented out the -keep class io.flutter.app.** { *; } and the -keep class io.flutter.** { *; } rules and now the app release builds successfully. That section of the rules looks like this now:

# https://github.com/flutter/flutter/issues/78625#issuecomment-804164524
#-keep class io.flutter.app.** { *; }
-keep class io.flutter.plugin.** { *; }
-keep class io.flutter.util.** { *; }
-keep class io.flutter.view.** { *; }
#-keep class io.flutter.** { *; }
-keep class io.flutter.plugins.** { *; }

With this I don't need to add any dontwarn or keep rules about the cited com.google.android.play.core... classes. The resulting apk operates fine.

Answer 2

Add the following line to the release section of your app's build.gradle:

proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'

This configures the proguard rules files for your Android app, and I have no idea why it's not included by default.