IssueTracker

Jetpack Compose version: March 2023 BOM

Jetpack Compose component(s) used: Compiler 1.4.4

Android Studio Build: N/A

Kotlin version: 1.8.10

Steps to Reproduce or Code Sample to Reproduce:

Passing an extension property reference triggers recomposition of the callee whenever the caller recomposes. By contrast, this is not true when passing an extension function reference. Marking the property getter @Stable does not help, either.

If the extension property behavior cannot be improved, then a Lint rule needs to be added warning about using inefficient extension property reference usages as opposed to using an equivalent lambda instead, which does not suffer from this problem.

Core repro below, complete repro project at https://github.com/bubenheimer/composeextensionpropertyrecomposition

@Composable
fun Screen() {
    var counter by remember { mutableStateOf(0) }

    Bar(Foo::asStringFun)
    Bar(Foo::asStringVal)

    LaunchedEffect(counter) {
        println("Recomposition $counter")
        if (counter < 10) ++counter
    }
}

@Composable
fun Bar(stringProvider: () -> String) {
    SideEffect { println("Recomposing: ${stringProvider()}") }
}

@Immutable
object Foo

fun Foo.asStringFun(): String = "$this foo fun"

val Foo.asStringVal: String
    get() = "$this foo val"