MotionLayout is not compatible with R8 full mode (without proguard rules)

[h6ah4i]

I faced an app crash when using R8 full mode which removes constructors more aggressively.

MotionLayout is using getConstructor() method in the KeyFrames class here :point_down: and it cause the problem. https://github.com/androidx/constraintlayout/blob/eb540e400fd01d6c4e3f795343a8f548d83aef3f/constraintlayout/constraintlayout/src/main/java/androidx/constraintlayout/motion/widget/KeyFrames.java#L50

The following proguard rule resolves the issue, but I think this should be bundled in consumerProguard by default.

-keepclassmembers class * extends androidx.constraintlayout.motion.widget.Key {
  public <init>();
}

[jafu888]

Would this not cause people simply using ConstraintLayout to have their APK increase in size? The majority of people using ConstraintLayout are not using MotionLayout (An argument for it being 2 libraries )

The AndroidStudio should add this to your proguard rules. We am not very familiar with the capabilities of progard.txt and we will be looking into it more

[Nailik]

This should be fixed ASAP as since Gradle 8.0 R8 full mode is on per default

https://developer.android.com/build/releases/gradle-plugin

[GSala]

I'm also running into this issue. My KeyFrames do not work - they are ingored, no crashes so far - if R8 full mode is enabled

[jafu888]

We will directly link in the future. We will move away from use of Java Reflection APIs.

[oguzhanaslann]

I had the same issue and I solved the problem by moving <KeyFrame> features to <ConstraintSet>.