IssueTracker

Thanks for the details. This is a duplicate of b/137836288. The issue here is that the field of type SharedPreferences.OnSharedPreferenceChangeListener is never read, and therefore R8 will remove the field assignment.

As described in b/137836288#comment19, a good approach to dealing with this kind of issue is to annotate your SharedPreferences.OnSharedPreferenceChangeListener field with a @ProtectWeakReference annotation:

public @interface ProtectWeakReference {}

You can then add the following generic keep rule to ensure that R8 does not remove the field assignment, despite the field never being read.

-keepclassmembers,allowobfuscation,allowshrinking class * {
  @pkg.ProtectWeakReference <fields>;
}

There are no recent changes to the handling of weak references. Each new version of R8 should generally shrink better than the previous version. It could be that the field in your app was not removed with the previous version of R8, but that the new version of R8 is now sophisticated enough to optimize it away.

If you are interested in finding the fields that are removed with a new version of R8, you could consider building your app with R8 version X.Y and R8 version U.V, disassembling the two APKs, and computing the diff of the retained fields (you probably want to add -dontobfuscate to simplify the diffing of the two).

Sorry for late reply and thank you for explanation. FYI, This issue happen again after we udpating to 7.3, now we have to remove allowobfuscation,allowshrinking to make it work:

-keepclassmembers class * { @pkg.ProtectWeakReference <fields>; }

Thank you