Endless re-layout of `TextField` with `singleLine = true` and intrinsic measurement about compose-multiplatform

[m-sasha]

This is a problem with real runs, not just tests. The measuring and layout gets into an infinite remeasure/relayout loop on every frame.

Reproduces in 1.6.x, but not in 1.5.12

[m-sasha]

Reproducer:

fun main() = singleWindowApplication {
    val state = remember { mutableStateOf(1) }
    Layout(
        measurePolicy = { measurables, constraints ->
            val measurable = measurables.first()
            val placeable = measurable.measure(constraints)
            val prevValue = Snapshot.withoutReadObservation {
                state.value
            }
            state.value = prevValue+1
            layout(100, 100) {
                state.value  // Read the state value!
                placeable.placeRelative(0, 0)
            }
        },
        content = {
            Text("Hello")
        }
    )
}

[m-sasha]

What happens here is:

1. The state is written in the measure phase, and GlobalSnapshotManager receives a write notification and schedules calling Snapshot.sendApplyNotifications(), but it's not yet called because the main thread is busy.
2. The layout phase happens, which reads the state, marking the scope as having read it.
3. When the rendering of the current frame (BaseComposeScene.render() ) completes, the GSM calls Snapshot.sendApplyNotifications(), the scope reports that it has read that state, so the scope is marked as invalid.
4. The next time BaseComposeScene.render() is called, the whole thing repeats from 1.

This appears to be a bug, because the state is read after it has been written to, so it should not mark the scope as invalid.

There are several differences in Android that "cover" for this, preventing the infinite relayout:

• Between the layout and drawing phases, Android's Choreographer flushes the tasks scheduled by the main dispatcher, which includes the GSM. This means that the scope is marked as invalid before the drawing phase.
• Android's drawing phase (AndroidComposeView.dispatchDraw) actually calls measureAndLayout again before drawing. This causes the layout scope to be executed again, and its invalidation state is cleared.

Additionally, in CMP, we don't mark nodes only for layout. Our Owner.onRequestRelayout implementation actually marks the node as needing to be measured. So even if we add Snapshot.sendApplyNotifications() and doLayout() between layout and draw, doLayout() will end up executing both measure and layout on the node, bringing us back to square one.