Commit f644021a authored Mar 25, 2025 by Steve Elliott

[kairos] Fix casting error in ActivatedKairosSpec

The `uninit` value is used as a sentinel to determine if the kairos spec
is currently active. If the state is not the same instance as `uninit`,
then we know that it is the value returned from the spec activation, and
so we can safely cast it.

The bug: `uninit` is a different instance when recomponsing, and so the
instance equality check fails, even though the value is *not* an
instance of `T`. This causes the cast to fail, which crashes the
process.

The solution: make `uninit` a private singleton that lives outside of
the composition. There will only ever be a single instance, and so the
instance equality check will now suffice.

Flag: com.android.systemui.status_bar_mobile_icon_kairos
Bug: 383172066
Change-Id: I57d06aba0e6d5b11ee13990eb78f7065314a5500

parent 62fbd662

packages/SystemUI/src/com/android/systemui/util/composable/kairos/ActivatedKairosSpec.kt

+5 −4

Original line number	Diff line number	Diff line
		@@ -41,20 +41,21 @@ fun <T> ActivatedKairosSpec(
		kairosNetwork: KairosNetwork,
		block: @Composable (T) -> Unit,
		) {
		val uninit = Any()
		var state by remember { mutableStateOf<Any?>(uninit) }
		var state by remember { mutableStateOf<Any?>(Uninitialized) }
		LaunchedEffect(key1 = Unit) {
		kairosNetwork.activateSpec {
		val v = buildSpec.applySpec()
		launchEffect {
		state = v
		awaitClose { state = uninit }
		awaitClose { state = Uninitialized }
		}
		}
		}
		state.let {
		if (it !== uninit) {
		if (it !== Uninitialized) {
		@Suppress("UNCHECKED_CAST") block(it as T)
		}
		}
		}

		private object Uninitialized