always run onDestroy functions

src/runtime/internal/Component.ts

@@ -54,7 +54,7 @@ export function destroy_component(component, detaching) {
 	if (component.$$.fragment) {
 		run_all(component.$$.on_destroy);
 
-		if (detaching) component.$$.fragment.d(1);
+		component.$$.fragment.d(detaching);
 
 		// TODO null out other refs, including component.$$ (but need to
 		// preserve final state?)

test/runtime/samples/ondestroy-deep/A.svelte

@@ -0,0 +1,15 @@
+<script>
+	import { onDestroy } from 'svelte';
+	import { destroyed } from './destroyed.js';
+	import B from './B.svelte';
+
+	let yes = 1;
+
+	onDestroy(() => destroyed.push('A'));
+</script>
+
+<div>
+	{#if yes}
+		<B/>
+	{/if}
+</div>

test/runtime/samples/ondestroy-deep/B.svelte

@@ -0,0 +1,15 @@
+<script>
+	import { onDestroy } from 'svelte';
+	import { destroyed } from './destroyed.js';
+	import C from './C.svelte';
+
+	let yes = 1;
+
+	onDestroy(() => destroyed.push('B'));
+</script>
+
+<div>
+	{#if yes}
+		<C/>
+	{/if}
+</div>

test/runtime/samples/ondestroy-deep/C.svelte

@@ -0,0 +1,8 @@
+<script>
+	import { onDestroy } from 'svelte';
+	import { destroyed } from './destroyed.js';
+
+	let yes = 1;
+
+	onDestroy(() => destroyed.push('C'));
+</script>

test/runtime/samples/ondestroy-deep/_config.js

@@ -0,0 +1,10 @@
+import { destroyed, reset } from './destroyed.js';
+
+export default {
+	test({ assert, component }) {
+		component.visible = false;
+		assert.deepEqual(destroyed, ['A', 'B', 'C']);
+
+		reset();
+	}
+};

test/runtime/samples/ondestroy-deep/destroyed.js

@@ -0,0 +1,3 @@
+export const destroyed = [];
+
+export const reset = () => destroyed.length = 0;

test/runtime/samples/ondestroy-deep/main.svelte

@@ -0,0 +1,9 @@
+<script>
+	import A from './A.svelte';
+
+	export let visible = true;
+</script>
+
+{#if visible}
+	<A/>
+{/if}