fix: beforeUpdate called twice with bound reference

src/runtime/internal/scheduler.ts

@@ -50,6 +50,7 @@ export function add_flush_callback(fn) {
 //    callback called a second time; the seen_callbacks set, outside the flush()
 //    function, guarantees this behavior.
 const seen_callbacks = new Set();
+let previous_dirty_components = new Set();
 let flushidx = 0;  // Do *not* move this inside the flush() function
 export function flush() {
 	// Do not reenter flush while dirty components are updated, as this can
@@ -69,10 +70,12 @@ export function flush() {
 				const component = dirty_components[flushidx];
 				flushidx++;
 				set_current_component(component);
-				update(component.$$);
+				const is_previous_dirty = previous_dirty_components.has(component);
+				update(component.$$, is_previous_dirty);
 			}
 		} catch (e) {
 			// reset dirty state to not end up in a deadlocked state and then rethrow
+			previous_dirty_components.clear();
 			dirty_components.length = 0;
 			flushidx = 0;
 			throw e;
@@ -83,8 +86,10 @@ export function flush() {
 		dirty_components.length = 0;
 		flushidx = 0;
 
-		while (binding_callbacks.length) binding_callbacks.pop()();
-
+		while (binding_callbacks.length) {
+			binding_callbacks.pop()();
+		}
+		previous_dirty_components = new Set(dirty_components);
 		// then, once components are updated, call
 		// afterUpdate functions. This may cause
 		// subsequent updates...
@@ -108,17 +113,18 @@ export function flush() {
 
 	update_scheduled = false;
 	seen_callbacks.clear();
+	previous_dirty_components.clear();
 	set_current_component(saved_component);
 }
 
-function update($$) {
+function update($$, is_previous_dirty) {
 	if ($$.fragment !== null) {
 		$$.update();
-		run_all($$.before_update);
+		if (!is_previous_dirty) run_all($$.before_update);
 		const dirty = $$.dirty;
 		$$.dirty = [-1];
 		$$.fragment && $$.fragment.p($$.ctx, dirty);
-
+		// if (!is_previous_dirty) run_all($$.after_update);
 		$$.after_update.forEach(add_render_callback);
 	}
 }

test/runtime/samples/lifecycle-render-order-for-children-with-binding/Item.svelte

@@ -0,0 +1,30 @@
+<script>
+	import { onMount, beforeUpdate, afterUpdate } from 'svelte';
+	import order from './order.js';
+
+	let i;
+	export let index;
+	export let id;
+	export let name;
+
+	function logRender () {
+		order.push(`${index}: render`);
+		return index;
+	}
+
+	beforeUpdate(() => {
+		order.push(`${index}: beforeUpdate`);
+	});
+
+	afterUpdate(() => {
+		order.push(`${index}: afterUpdate`);
+	});
+
+	onMount(() => {
+		order.push(`${index}: onMount`);
+	});
+</script>
+
+<li bind:this={i}>
+	{logRender()}
+</li>

test/runtime/samples/lifecycle-render-order-for-children-with-binding/_config.js

@@ -0,0 +1,49 @@
+import order from './order.js';
+
+export default {
+	skip_if_ssr: true,
+	before_test() {
+		order.length = 0;
+	},
+	test({ assert, compileOptions }) {
+		if (compileOptions.hydratable) {
+			assert.deepEqual(order, [
+				'0: beforeUpdate',
+				'0: render',
+				'1: beforeUpdate',
+				'1: render',
+				'2: beforeUpdate',
+				'2: render',
+				'3: beforeUpdate',
+				'3: render',
+				'1: onMount',
+				'1: afterUpdate',
+				'2: onMount',
+				'2: afterUpdate',
+				'3: onMount',
+				'3: afterUpdate',
+				'0: onMount',
+				'0: afterUpdate'
+			]);
+		} else {
+			assert.deepEqual(order, [
+				'0: beforeUpdate',
+				'0: render',
+				'1: beforeUpdate',
+				'2: beforeUpdate',
+				'3: beforeUpdate',
+				'1: render',
+				'2: render',
+				'3: render',
+				'1: onMount',
+				'1: afterUpdate',
+				'2: onMount',
+				'2: afterUpdate',
+				'3: onMount',
+				'3: afterUpdate',
+				'0: onMount',
+				'0: afterUpdate'
+			]);
+		}
+	}
+};

test/runtime/samples/lifecycle-render-order-for-children-with-binding/main.svelte

@@ -0,0 +1,34 @@
+<script>
+	import { onMount, beforeUpdate, afterUpdate } from 'svelte';
+	import order from './order.js';
+	import Item from './Item.svelte';
+
+	const parentIndex = 0;
+	let ul;
+	let ulW;
+	function logRender () {
+  		order.push(`${parentIndex}: render`);
+  		return parentIndex;
+  	}
+
+  	beforeUpdate(() => {
+  		order.push(`${parentIndex}: beforeUpdate`);
+  	});
+
+  	afterUpdate(() => {
+  		order.push(`${parentIndex}: afterUpdate`);
+  	});
+
+  	onMount(() => {
+  		order.push(`${parentIndex}: onMount`);
+  	})
+</script>
+
+{logRender()}
+<ul bind:this={ul} bind:clientWidth={ulW}>
+	{#each [1,2,3] as index}
+		<Item {index} />
+	{/each}
+</ul>
+
+

test/runtime/samples/lifecycle-render-order-for-children-with-binding/order.js

@@ -0,0 +1 @@
+export default [];