Function Child1

compat/test/browser/useSyncExternalStore.test.jsx:511–524

({ step })

			const getSnapshotB = () => store.getState().b;

			function Child1({ step }) {
				const value = useSyncExternalStore(store.subscribe, store.getState);
				useLayoutEffect(() => {
					if (step === 1) {
						// Update B in a layout effect. This happens in the same commit
						// that changed the getSnapshot in Child2. Child2's effects haven't
						// fired yet, so it doesn't have access to the latest getSnapshot. So
						// it can't use the getSnapshot to bail out.
						Scheduler.log('Update B in commit phase');
						store.set({ a: value.a, b: 2 });
					}
				}, [step]);
				return null;
			}

			function Child2({ step }) {
				const label = step === 0 ? 'A' : 'B';