fix: add top level snippets to instance scope

fixes #9460

.changeset/rich-sheep-burn.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: add top level snippets to instance scope

packages/svelte/src/compiler/phases/scope.js

@@ -273,15 +273,6 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 		next({ scope });
 	};
 
-	/**
-	 * @type {import('zimmerframe').Visitor<import('#compiler').SvelteNode, State, import('#compiler').SvelteNode>}
-	 */
-	const CreateBlock = (node, { state, next }) => {
-		const scope = state.scope.child();
-		scopes.set(node, scope);
-		next({ scope });
-	};
-
 	/**
 	 * @param {import('#compiler').ElementLike} node
 	 * @param {Scope} parent
@@ -566,18 +557,24 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 		},
 
 		SnippetBlock(node, context) {
-			state.scope.declare(node.expression, 'normal', 'function', node.expression);
+			// Special-case for root-level snippets: they become part of the instance scope
+			const is_top_level = !context.path.at(-2);
+			let scope = state.scope;
+			if (is_top_level) {
+				scope = /** @type {Scope} */ (parent);
+			}
+			scope.declare(node.expression, 'normal', 'function', node.expression);
 
-			const scope = state.scope.child();
-			scopes.set(node, scope);
+			const child_scope = state.scope.child();
+			scopes.set(node, child_scope);
 
 			if (node.context) {
 				for (const id of extract_identifiers(node.context)) {
-					scope.declare(id, 'each', 'let');
+					child_scope.declare(id, 'each', 'let');
 				}
 			}
 
-			context.next({ scope });
+			context.next({ scope: child_scope });
 		},
 
 		Fragment: (node, context) => {
@@ -586,9 +583,6 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 			context.next({ scope });
 		},
 
-		// TODO this will be unnecessary when we switch to fragments
-		IfBlock: CreateBlock,
-
 		BindDirective(node, context) {
 			updates.push([
 				context.state.scope,

packages/svelte/tests/snapshot/samples/snippet-hoisting/_expected/client/input.svelte.js

@@ -0,0 +1,31 @@
+// input.svelte (Svelte VERSION)
+// Note: compiler output will change before 5.0 is released!
+import "svelte/internal/disclose-version";
+import * as $ from "svelte/internal";
+
+function log(_, snippet) {
+	console.log(snippet);
+}
+
+var frag_1 = $.template(`Hello`, true);
+var frag = $.template(`<button>log snippet</button>`);
+
+export default function Input($$anchor, $$props) {
+	$.push($$props, false);
+
+	/* Init */
+	var button = $.open($$anchor, true, frag);
+
+	function snippet($$anchor) {
+		/* Init */
+		var fragment = $.open_frag($$anchor, true, frag_1);
+
+		$.close_frag($$anchor, fragment);
+	}
+
+	button.__click = [log, snippet];
+	$.close($$anchor, button);
+	$.pop();
+}
+
+$.delegate(["click"]);

packages/svelte/tests/snapshot/samples/snippet-hoisting/_expected/server/input.svelte.js

@@ -0,0 +1,22 @@
+// input.svelte (Svelte VERSION)
+// Note: compiler output will change before 5.0 is released!
+import * as $ from "svelte/internal/server";
+
+export default function Input($$payload, $$props) {
+	$.push(false);
+
+	function log() {
+		console.log(snippet);
+	}
+
+	function snippet($$payload) {
+		const anchor = $.create_anchor($$payload);
+
+		$$payload.out += anchor;
+		$$payload.out += `Hello`;
+		$$payload.out += anchor;
+	}
+
+	$$payload.out += `<button>log snippet</button>`;
+	$.pop();
+}

packages/svelte/tests/snapshot/samples/snippet-hoisting/input.svelte

@@ -0,0 +1,11 @@
+<script>
+	function log() {
+		console.log(snippet)
+	}
+</script>
+
+{#snippet snippet()}Hello{/snippet}
+
+<button on:click={log}>
+	log snippet
+</button>