fix: update blocks that reference deriveds with $state.eager

Author: Rich-Harris

packages/svelte/tests/runtime-runes/samples/async-state-eager-if/_config.js

@@ -0,0 +1,57 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	mode: ['client'],
+
+	compileOptions: {
+		dev: true
+	},
+
+	async test({ assert, target }) {
+		const [count, shift] = target.querySelectorAll('button');
+
+		shift.click();
+		await tick();
+		assert.htmlEqual(target.innerHTML, `<button>0</button><button>shift</button><p>0</p>`);
+
+		count.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			`<button>1</button><button>shift</button><p>0</p><p>updating</p>`
+		);
+
+		count.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			`<button>2</button><button>shift</button><p>0</p><p>updating</p>`
+		);
+
+		count.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			`<button>3</button><button>shift</button><p>0</p><p>updating</p>`
+		);
+
+		shift.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			`<button>3</button><button>shift</button><p>1</p><p>updating</p>`
+		);
+
+		shift.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			`<button>3</button><button>shift</button><p>2</p><p>updating</p>`
+		);
+
+		shift.click();
+		await tick();
+		assert.htmlEqual(target.innerHTML, `<button>3</button><button>shift</button><p>3</p>`);
+	}
+});

packages/svelte/tests/runtime-runes/samples/async-state-eager-if/main.svelte

@@ -0,0 +1,25 @@
+<script>
+	let count = $state(0);
+	let eager = $derived($state.eager(count));
+
+	let resolvers = [];
+
+	function push(value) {
+		const { promise, resolve } = Promise.withResolvers();
+		resolvers.push(() => resolve(value));
+		return promise;
+	}
+</script>
+
+<button onclick={() => count += 1}>{eager}</button>
+<button onclick={() => resolvers.shift()?.()}>shift</button>
+
+<svelte:boundary>
+	<p>{await push(count)}</p>
+
+	{#if count !== eager}
+		<p>updating</p>
+	{/if}
+
+	{#snippet pending()}{/snippet}
+</svelte:boundary>