IssueTracker

Thanks for the feedback. Can you please share some more details on what kind of issues you are experiencing?

This has also been asked on StackOverflor: https://stackoverflow.com/questions/79510709/all-overridden-methods-are-being-converted-to-final-after-r8-obfuscates

Can you please shed some more light on why this is a problem? Do you run any dex-to-dex transformations after running R8 or do you perform dynamic code loading?

Looking at the build.gradle file it looks like you are missing the default rules provided by AGP. You release configuration is:

    buildTypes {
        release {
            minifyEnabled true
            proguardFiles 'proguard-rules.pro'
        }
    }

which should include getDefaultProguardFile('proguard-android-optimize.txt') like this:

    buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }

Please check if that addresses the issue. It might not if you are also dynamic code loading as mentioned in comment #5. R8 is a whole program optimizer, and if the whole program is not provided, rules are requires to specify where whole program optimizations cannot be done. E.g. if a class has subclasses at runtime, but not at compile time R8 will assume no subclasses and can then make virtual methods final.

You can see the combined rules in app/build/outputs/mapping/release/configuration.txt to validate. These rules should also contain any rules generated by aapt2.

Again, can you please shed some more light on why this is a problem? Making MainActivity#onCreate final should be a perfectly valid performance optimization.

Does your app crash at runtime? If so, do you have a subclass of MainActivity that overrides MainActivity#onCreate? Can you share the logcat of the error?

The class file shown in comment #9 is from an aar. Is the code you are building an Android Library and not an android app? If the library is used in a way where onCreate is overridden, then I would expect the compilation to fail. If that is not the case then it still looks like you are not providing the whole program to the app build but loading additional classes at runtime.

Thanks for the extra information. It makes sense that this can be an issue when building a library. This is ultimately due to missing keep rules. In order to guarantee that classes/fields/methods will not be optimized they must be kept. When building a library it is therefore necessary to keep the public API surface of the library.

As an example, consider the R8Command in R8, which is annotated with a @KeepForApi annotation. This annotation is backed by a generic -keep rule that keeps all public and protected members of the class.

You could introduce an annotation @KeepForApi, annotate the public API surface of your library, and add the following rule.

-keep @com.example.KeepForApi class * {
  public *;
  protected *;
}

I am assuming that you must already have some keep rules to protect the API surface of your library, or do you only rely on the AAPT generated keep rules?

It should also be possible to avoid this issue by merely adding the following rule. Unlike the proposal above this may also prohibit optimization of the non-public API of your library,

-if class *
-keep,allowobfuscation,allowshrinking public class * {
  public *;
  protected *;
}

An alternative naive solution is to add -dontoptimize.