IssueTracker

Jetpack Compose version: BOM 2025.03.00 stable Jetpack Compose component used: runtime, ui, foundation Android Studio Build: Meerkat | 2024.3.1 | AGP 8.9.0 Kotlin version: 2.1.20

Steps to Reproduce or Code Sample to Reproduce:

Upgrade from Kotlin 2.1.10 to 2.1.20 (all other deps & tools stay the same)

Code with this nesting structure is causing a runtime ClassCastException:

// Simplified & annotated & redacted; most nesting levels have siblings
@Composable
fun MyFunction(state: FunctionState, ...) {
  CompositionLocalProvider(...) {
    Box(...) {
      // ForEachRecord is a Composable (not inlined) member function with a
      // lambda with signature: @Composable (Int, MyRecord, MyRecord?) -> Unit
      state.ForEachRecord { index, a, b -> // <- stack trace points here (line 220)
        key(a.id) {
          OtherComposable(
            Modifier.pointerInput(Unit) { // <- stack trace points here (line 241)
              detectTapGestures { state.doSomething(a) }
            }
          ) {
            Box { a.content() }
          }
        }
      }
    }
  }
}

This seems very sensitive to refactoring:

• Extract state.doSomething(a) to a local lambda, no crash
  • i.e. detectTapGestures { extractedLambda() }
• Extract contents of key(a.id) to a separate top-level composable, no crash
• Moving key(a.id) into ForEachRecord, no crash
• Reordering OtherComposable with siblings, which have lambdas, no crash

Some refactors that do not work:

• Extract the pointer input "logic" to it's own modifier function, still crashes
  • i.e. pointerInput {} -> tapToActivate { state.doSomething(a) }

Based on my knowledge of lambda naming conventions, I was pretty sure $1$2$3 was too high up the nesting to be the lambda for pointerInput.

Looking in Android Studio's Kotlin Bytecode viewer for this file, the lambda for pointerInput is ...MyFunction$1$2$3$3$1, which does implement Function2.

The class named ...MyFunction$1$2$3 is lambda for ForEachRecord, implements Function4.

Using dexdump to see the implementation of the ExternalSyntheticLambda0, it looks like it's the desugared lambda { state.doSomething(a) }, it's constructed with state and a types and implements Function1 (1 for unused parameter from detectTapGestures).

So maybe this is an issue with r8 desugaring? Please redirect if so.

Stack trace (if applicable):

// some renaming to match code sample above
FATAL EXCEPTION: main
Process: fm.here.there.android.debug, PID: 14996
java.lang.ClassCastException: my.package.FileKt$MyFunction$1$2$3$$ExternalSyntheticLambda0 cannot be cast to kotlin.jvm.functions.Function2
	at my.package.FileKt$MyFunction$1$2$3.invoke(MyFunction.kt:241)
	at my.package.FileKt$MyFunction$1$2$3.invoke(MyFunction.kt:220)
	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:161)
	at androidx.compose.runtime.internal.ComposableLambdaImpl$invoke$3.invoke(ComposableLambda.jvm.kt:177)
	at androidx.compose.runtime.internal.ComposableLambdaImpl$invoke$3.invoke(ComposableLambda.jvm.kt:176)
	at androidx.compose.runtime.RecomposeScopeImpl.compose(RecomposeScopeImpl.kt:192)
	at androidx.compose.runtime.ComposerImpl.recomposeToGroupEnd(Composer.kt:2825)
	at androidx.compose.runtime.ComposerImpl.skipCurrentGroup(Composer.kt:3116)
	at androidx.compose.runtime.ComposerImpl.doCompose(Composer.kt:3607)
	at androidx.compose.runtime.ComposerImpl.recompose$runtime_release(Composer.kt:3552)
	at androidx.compose.runtime.CompositionImpl.recompose(Composition.kt:948)
	at androidx.compose.runtime.Recomposer.performRecompose(Recomposer.kt:1206)
	at androidx.compose.runtime.Recomposer.access$performRecompose(Recomposer.kt:132)
	at androidx.compose.runtime.Recomposer$runRecomposeAndApplyChanges$2$1.invoke(Recomposer.kt:616)
	at androidx.compose.runtime.Recomposer$runRecomposeAndApplyChanges$2$1.invoke(Recomposer.kt:585)
	at androidx.compose.ui.platform.AndroidUiFrameClock$withFrameNanos$2$callback$1.doFrame(AndroidUiFrameClock.android.kt:41)
	at androidx.compose.ui.platform.AndroidUiDispatcher.performFrameDispatch(AndroidUiDispatcher.android.kt:109)
	at androidx.compose.ui.platform.AndroidUiDispatcher.access$performFrameDispatch(AndroidUiDispatcher.android.kt:41)
	at androidx.compose.ui.platform.AndroidUiDispatcher$dispatchCallback$1.doFrame(AndroidUiDispatcher.android.kt:69)
	at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1564)
	at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1575)
	at android.view.Choreographer.doCallbacks(Choreographer.java:1175)
	at android.view.Choreographer.doFrame(Choreographer.java:1100)
	at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1549)
	at android.os.Handler.handleCallback(Handler.java:991)
	at android.os.Handler.dispatchMessage(Handler.java:102)
	at android.os.Looper.loopOnce(Looper.java:232)
	at android.os.Looper.loop(Looper.java:317)
	at android.app.ActivityThread.main(ActivityThread.java:8934)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:591)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:911)
	Suppressed: kotlinx.coroutines.internal.DiagnosticCoroutineContextException: [androidx.compose.runtime.PausableMonotonicFrameClock@e91b464, androidx.compose.ui.platform.MotionDurationScaleImpl@25876cd, StandaloneCoroutine{Cancelling}@36b3b82, AndroidUiDispatcher@9562293]