IssueTracker

Thanks for the report. If the data class SocialImage is only instantiated by reflection (by gson), then a keep rule is needed to specify this. Otherwise R8 will treat the class as never being instantiated, and remove its constructor(s).

Could you please try to build with the following rule?

-if class * {
  @com.google.gson.annotations.SerializedName <fields>;
}
-keep class <1> {
  <init>();
}

The change in comment #4 fixes an issue related to the interpretation of the rule in comment #2. I will try to reproduce the exact issue you are running into. Could you share which version of Gson you are using?

If you would be able to share an Android Studio project where this reproduces that would be super helpful. Snippets of the relevant code might also suffice for us to reproduce the problem.

For the record, I've managed to reproduce the problem.

We've been analyzing the problem, and came to the conclusion that no fixes should be needed for this to work. Instead, you need the following slightly stronger rule with R8 in full mode:

-if class *
-keepclasseswithmembers class <1> {
  <init>(...);
  @com.google.gson.annotations.SerializedName <fields>;
}

I hope this solves your problem!

Yes, that will also do the trick. Note that @Keep will prevent the getters (and all other methods) on your data classes from being inlined (and thus removed). The rule in comment #11 doesn't have this side effect.

I would suggest using the version of R8 that is bundled with AGP, at least if you update AGP regularly.

You can also build using a more recent version of R8 (e.g., 2.0.38, or even 2.1.8-dev) by making the following changes to build.gradle.

buildscript {
    repositories {
        maven {
            url 'https://storage.googleapis.com/r8-releases/raw'
        }
    }
    dependencies {
        classpath 'com.android.tools:r8:2.0.38'          // Must be before the Gradle Plugin for Android.
        classpath 'com.android.tools.build:gradle:X.Y.Z' // Your current AGP version.
     }
}

However, this has the disadvantage that, if you update AGP, but forget to update R8, then you will be stuck on the old version of the compiler.

The R8 versions can be found from https://r8.googlesource.com/r8/ (the 2.0 releases are at https://r8.googlesource.com/r8/+/refs/heads/2.0).

When the --info option is passed to AGP the version of R8 will be printed, e.g. for AGP 3.6.0 the follwing line will be printed:

Current version is: 1.6.67 (build 63035baeff4ab2f5079d99c54d86d9a4839c158c from go/r8bot (luci-r8-ci-xenial-7-83cg)).

To just rerun the R8 release task (to get that version number) the following command can be used:

./gradlew --info :app:cleanMinifyReleaseWithR8 :app:minifyReleaseWithR8

I have slight diff. error coming with AGP 8.0 and Android studio flamingo.

Using Retrofit with gson gives error related to Abstract class can't be initiated.

But i solved this error with comment #11 rule as below

-if class *

-keepclasseswithmembers class <1> {

<init>(...);

@com.google.gson.annotations.SerializedName <fields>;

}