IssueTracker

I can see that I didn't manage to reproduce the error. So, I've cloned the R8 repo and tried debugging it myself. First thing to note is that everything looks like it's working when I checkout master and build it. On branch 1.6 though, I can see the error:

In the ProguardMapMinifier, checkAndAddMappedNames is called with

type: com.google.android.play.core.internal.o
mappedName: Lcom/google/android/play/core/internal/k;
position: offset: 0, line: 126176, column: 1

The inverse of mappedNames contains the mappedName above, and also inverse.get(mappedName) returns a DexType of com.google.android.play.core.internal.k, which is different from the type and therefore fails.

I don't really know the codebase, but it looks like the issue might be in the computeMapping method inside ProguardMapMinifier.java, where calling seedMapper.getClassNaming(com.google.android.play.core.internal.o) returns a ClassNamingForMapApplier that has

originalName Lcom/google/android/play/core/internal/o;
renamedName Lcom/google/android/play/core/internal/k;

Hope this helps, let me know if I can provide more info.

Was the Google Play core library added as a dependency to the app and tests? If yes, can I ask you to check the produced mapping file by R8 to see if the name that R8 reports an error on is in the mapping file. If that is the case, what is happening is that the library, which is already minified, is then minified again and we will almost certainly pick another one-letter name.

For simplicity, say there is only two classes: foo.bar.a foo.bar.b

If we, when we compile the app with R8 determine that foo.bar.a is not used, we will remove it (it will not be in the mapping file) and we will rename foo.bar.b -> foo.bar.a

When we then compile the tests, that has the original files, we will try and rename foo.bar.b to foo.bar.a, but, that class already exists and we do not have a mapping for it.

I'm almost certain the above is the case - if the Google Play core library was added as a dependency to the tests and we have something that maps to 'Lcom/google/android/play/core/appupdate/j in the mapping file. Can you confirm my suspicion?

As far as I can see it is added only as implementation, never as testImplementation or androidTestImplementation. The PR that introduced it in the project is not really big, and it adds the Play library as implementation in one module and as api in another. In the mapping.txt, looking for com.google.android.play.core.appupdate.j, I can see:

com.google.android.play.core.appupdate.AppUpdateInfo -> com.google.android.play.core.appupdate.a:
com.google.android.play.core.appupdate.a -> com.google.android.play.core.appupdate.c:
com.google.android.play.core.appupdate.c -> com.google.android.play.core.appupdate.e:
com.google.android.play.core.appupdate.e -> com.google.android.play.core.appupdate.g:
com.google.android.play.core.appupdate.g -> com.google.android.play.core.appupdate.i:
com.google.android.play.core.appupdate.i -> com.google.android.play.core.appupdate.j:

The library is then only used in a robolectric test. It's worth mentioning that we use Keeper to infer test rules for our test apk, but looking into the generated rules there's not really anything related to com.google.android.play.core.*

lorenzo.quiroli@, can I ask you to try out 69f1d4d25429cc13e5b8028a7491c97e8ea37fc0 by adding the following to your top-level build.gradle file (and removing any special keep-rules that circumvent the issue):

buildscript {

    repositories {
        maven {
            url "https://storage.googleapis.com/r8-releases/raw/master"
        }
    }

    dependencies {
        classpath 'com.android.tools:r8:69f1d4d25429cc13e5b8028a7491c97e8ea37fc0'  // Must be before the Gradle Plugin for Android.
        classpath 'com.android.tools.build:gradle:X.Y.Z'     // Your current AGP version.
     }
}

I can confirm it's working now, wonderful! Would you be able to tell me in which release it will be included?

It could either be included in 4.0 beta 3 or 4.0 stable, depending on the release schedule for Android Studio. It was not feasible to port back to the current release. You can point to the 2.0.47 version by adding the following to your top-level build.gradle file:

buildscript {

    repositories {
        maven {
            url 'https://storage.googleapis.com/r8-releases/raw'
        }
    }

    dependencies {
        classpath 'com.android.tools:r8:2.0.47'          // Must be before the Gradle Plugin for Android.
        classpath 'com.android.tools.build:gradle:X.Y.Z' // Your current AGP version.
     }
}