Android R8: Type a.a is defined multiple times

Question

exact error is

ERROR: /Users/REDACT/.gradle/caches/transforms-4/8d2b49e30523efece47d2329e1531ac9/transformed/classes.jar: R8: Type a.a is defined multiple times: /Users/mgh01/.gradle/caches/transforms-4/8d2b49e30523efece47d2329e1531ac9/transformed/classes.jar:a/a.class, /Users/REDACT/.gradle/caches/transforms-4/196d8149ca78d42bf3bbca1f74e91807/transformed/classes.jar:a/a.class

I've looked up the classes.jar of both and the offending class is just

an

public interface a {}

This is all come off the back of updating the AGP to the latest 8.5.0.

Also running R8 in the "compatibility" mode makes no difference.

I've also tried to disable obfuscation so I can see what a is meant to be but it the same

Any help would be appreciated

Answer 1

I had a similar problem and found a fix for my project composed of :

• an App module

  plugins { id 'com.android.application' }

• some other library modules

  plugins { id 'com.android.library') }

It worked fine with AGP <= 8.3.2 but stopped working with 8.4.0+

The fix consisted to enable Minification only at the App Level for the release buildType.

In build.gradule (Module: app):

buildTypes {
    debug {
        minifyEnabled false
    }
    release {
        minifyEnabled true
    }
}

and in other modules:

buildTypes {
    debug {
        minifyEnabled false
    }
    release {
        minifyEnabled false
    }
}

I think it may have something to do with the note about "Library classes are shrunk" in the release note of AGP 8.4.0 and the parameter android.disableMinifyLocalDependenciesForLibraries in the gradle.properties (though it didn't work for my project)

cf: https://developer.android.com/build/releases/past-releases/agp-8-4-0-release-notes?hl=fr#library-classes-shrunk

More, in Android builds, R8 is run once during the final stage of building the APK or AAB, which is the step where the entire application is assembled:

The minifyEnabled flag at the app module level means that all the code, including code from library modules, is considered during minification. If library modules have minifyEnabled set to true, they would attempt to minify their code independently, potentially leading to conflicts when the app module tries to do the same during its build process.