fix slot fallback update parent (sveltejs#4598)

CHANGELOG.md

@@ -6,6 +6,7 @@
 * Try using `globalThis` rather than `globals` for the benefit of non-Node servers and web workers ([#3561](https://github.com/sveltejs/svelte/issues/3561), [#4545](https://github.com/sveltejs/svelte/issues/4545))
 * Support `{#await ... catch ...}` syntax shorthand ([#3623](https://github.com/sveltejs/svelte/issues/3623))
 * Fix attaching of JS debugging comments to HTML comments ([#4565](https://github.com/sveltejs/svelte/issues/4565))
+* Fix `<svelte:component/>` within `<slot/>` ([#4597](https://github.com/sveltejs/svelte/issues/4597))
 * Fix issues with `<input type="number">` updates ([#4631](https://github.com/sveltejs/svelte/issues/4631), [#4687](https://github.com/sveltejs/svelte/issues/4687))
 * Prevent illegal attribute names ([#4648](https://github.com/sveltejs/svelte/issues/4648))
 * Fix `{#if}` block directly within `<slot/>` ([#4703](https://github.com/sveltejs/svelte/issues/4703))

test/runtime/samples/component-slot-fallback-5/IconA.svelte

@@ -0,0 +1 @@
+Icon A

test/runtime/samples/component-slot-fallback-5/IconB.svelte

@@ -0,0 +1 @@
+Icon B

test/runtime/samples/component-slot-fallback-5/Inner.svelte

@@ -0,0 +1,13 @@
+<script>
+	import IconA from './IconA.svelte';
+	import IconB from './IconB.svelte';
+
+	let variable = false;
+</script>
+
+<button on:click={() => variable = !variable}>Click Me</button>
+<div>
+	<slot>
+		<svelte:component this={variable ? IconA : IconB} />
+	</slot>
+</div>

test/runtime/samples/component-slot-fallback-5/_config.js

@@ -0,0 +1,31 @@
+export default {
+	html: `
+	<button>Click Me</button>
+	<div>Icon B</div>
+	`,
+
+	async test({ assert, target, window }) {
+		const btn = target.querySelector("button");
+		const clickEvent = new window.MouseEvent("click");
+
+		await btn.dispatchEvent(clickEvent);
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+			<button>Click Me</button>
+			<div>Icon A</div>
+			`
+		);
+
+		await btn.dispatchEvent(clickEvent);
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+			<button>Click Me</button>
+			<div>Icon B</div>
+			`
+		);
+	}
+};

test/runtime/samples/component-slot-fallback-5/main.svelte

@@ -0,0 +1,5 @@
+<script>
+	import Inner from "./Inner.svelte";
+</script>
+
+<Inner></Inner>