fix: hoist snippets above const in same block (#17516)

* fix: hoist snippets above const in same block

* fix: type error

.changeset/blue-parts-double.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: hoist snippets above const in same block

packages/svelte/src/compiler/phases/3-transform/client/transform-client.js

@@ -170,6 +170,7 @@ export function client_component(analysis, options) {
 		// these are set inside the `Fragment` visitor, and cannot be used until then
 		init: /** @type {any} */ (null),
 		consts: /** @type {any} */ (null),
+		snippets: /** @type {any} */ (null),
 		let_directives: /** @type {any} */ (null),
 		update: /** @type {any} */ (null),
 		after_update: /** @type {any} */ (null),

packages/svelte/src/compiler/phases/3-transform/client/types.d.ts

@@ -49,6 +49,8 @@ export interface ComponentClientTransformState extends ClientTransformState {
 	readonly update: Statement[];
 	/** Stuff that happens after the render effect (control blocks, dynamic elements, bindings, actions, etc) */
 	readonly after_update: Statement[];
+	/** Transformed `{#snippets }` declarations */
+	readonly snippets: Statement[];
 	/** Transformed `{@const }` declarations */
 	readonly consts: Statement[];
 	/** Transformed async `{@const }` declarations (if any) and those coming after them */

packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js

@@ -1,13 +1,13 @@
 /** @import { Expression, Statement } from 'estree' */
 /** @import { AST } from '#compiler' */
 /** @import { ComponentClientTransformState, ComponentContext } from '../types' */
-import { TEMPLATE_FRAGMENT, TEMPLATE_USE_IMPORT_NODE } from '../../../../../constants.js';
 import * as b from '#compiler/builders';
+import { TEMPLATE_FRAGMENT, TEMPLATE_USE_IMPORT_NODE } from '../../../../../constants.js';
 import { clean_nodes, infer_namespace } from '../../utils.js';
 import { transform_template } from '../transform-template/index.js';
+import { Template } from '../transform-template/template.js';
 import { process_children } from './shared/fragment.js';
 import { build_render_statement, Memoizer } from './shared/utils.js';
-import { Template } from '../transform-template/template.js';
 
 /**
  * @param {AST.Fragment} node
@@ -60,6 +60,7 @@ export function Fragment(node, context) {
 	const state = {
 		...context.state,
 		init: [],
+		snippets: [],
 		consts: [],
 		let_directives: [],
 		update: [],
@@ -150,7 +151,7 @@ export function Fragment(node, context) {
 		}
 	}
 
-	body.push(...state.let_directives, ...state.consts);
+	body.push(...state.snippets, ...state.let_directives, ...state.consts);
 
 	if (state.async_consts && state.async_consts.thunks.length > 0) {
 		body.push(b.var(state.async_consts.id, b.call('$.run', b.array(state.async_consts.thunks))));

packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js

@@ -329,7 +329,7 @@ export function RegularElement(node, context) {
 	);
 
 	/** @type {typeof state} */
-	const child_state = { ...state, init: [], update: [], after_update: [] };
+	const child_state = { ...state, init: [], update: [], after_update: [], snippets: [] };
 
 	for (const node of hoisted) {
 		context.visit(node, child_state);
@@ -441,6 +441,7 @@ export function RegularElement(node, context) {
 		// Wrap children in `{...}` to avoid declaration conflicts
 		context.state.init.push(
 			b.block([
+				...child_state.snippets,
 				...child_state.init,
 				...element_state.init,
 				child_state.update.length > 0 ? build_render_statement(child_state) : b.empty,

packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js

@@ -89,6 +89,6 @@ export function SnippetBlock(node, context) {
 			context.state.instance_level_snippets.push(declaration);
 		}
 	} else {
-		context.state.init.push(declaration);
+		context.state.snippets.push(declaration);
 	}
 }

packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js

@@ -77,7 +77,7 @@ export function SvelteBoundary(node, context) {
 				/** @type {Statement[]} */
 				const statements = [];
 
-				context.visit(child, { ...context.state, init: statements });
+				context.visit(child, { ...context.state, snippets: statements });
 
 				const snippet = /** @type {VariableDeclaration} */ (statements[0]);
 

packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js

@@ -333,7 +333,7 @@ export function build_component(node, component_name, loc, context) {
 			// can be used as props without creating conflicts
 			context.visit(child, {
 				...context.state,
-				init: snippet_declarations
+				snippets: snippet_declarations
 			});
 
 			push_prop(b.prop('init', child.expression, child.expression));

packages/svelte/tests/runtime-runes/samples/snippet-const-same-block/_config.js

@@ -0,0 +1,5 @@
+import { test } from '../../test';
+
+export default test({
+	test() {}
+});

packages/svelte/tests/runtime-runes/samples/snippet-const-same-block/main.svelte

@@ -0,0 +1,4 @@
+{#if true}
+	{@const xx = test}
+	{#snippet test()}{/snippet}
+{/if}