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androidandroid-fragmentsproguardandroidxandroid-r8

Android R8 fragments implements but actually matches extends

Currently used version is: androidx.fragment:fragment-ktx:1.2.1. When I try to build release version, proguard (R8) show warnings like: 

R8: The rule `-neverclassinline public class ** implements androidx.fragment.app.Fragment` uses implements but actually matches extends.

R8: The rule `-keep public class ** implements androidx.fragment.app.Fragment {
  public <init>();
}` uses implements but actually matches extends.

I didnt find any related issues on bug trackers. What maybe the reason, and how I can fix it?

Solution

  • This is issue 148963981, which is already marked as fixed for the (upcoming, as of the time of writing this answer) Fragment 1.2.2 release.