Merge branch 'main' into boundary-batch-nullpointer-fix

Author: dummdidumm

.changeset/cool-garlics-fail.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: place instance-level snippets inside async body

.changeset/silent-pigs-relax.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: restore batch along with effect context

documentation/docs/98-reference/.generated/compile-errors.md

@@ -196,6 +196,51 @@ Cyclical dependency detected: %cycle%
 `{@const}` must be the immediate child of `{#snippet}`, `{#if}`, `{:else if}`, `{:else}`, `{#each}`, `{:then}`, `{:catch}`, `<svelte:fragment>`, `<svelte:boundary` or `<Component>`
 ```
 
+### const_tag_invalid_reference
+
+```
+The `{@const %name% = ...}` declaration is not available in this snippet 
+```
+
+The following is an error:
+
+```svelte
+<svelte:boundary>
+    {@const foo = 'bar'}
+
+    {#snippet failed()}
+        {foo}
+    {/snippet}
+</svelte:boundary>
+```
+
+Here, `foo` is not available inside `failed`. The top level code inside `<svelte:boundary>` becomes part of the implicit `children` snippet, in other words the above code is equivalent to this:
+
+```svelte
+<svelte:boundary>
+    {#snippet children()}
+        {@const foo = 'bar'}
+    {/snippet}
+
+    {#snippet failed()}
+        {foo}
+    {/snippet}
+</svelte:boundary>
+```
+
+The same applies to components:
+
+```svelte
+<Component>
+    {@const foo = 'bar'}
+
+    {#snippet someProp()}
+        <!-- error -->
+        {foo}
+    {/snippet}
+</Component>
+```
+
 ### constant_assignment
 
 ```

packages/svelte/CHANGELOG.md

@@ -1,5 +1,29 @@
 # svelte
 
+## 5.38.3
+
+### Patch Changes
+
+- fix: ensure correct order of template effect values ([#16655](https://github.com/sveltejs/svelte/pull/16655))
+
+- fix: allow async `{@const}` in more places ([#16643](https://github.com/sveltejs/svelte/pull/16643))
+
+- fix: properly catch top level await errors ([#16619](https://github.com/sveltejs/svelte/pull/16619))
+
+- perf: prune effects without dependencies ([#16625](https://github.com/sveltejs/svelte/pull/16625))
+
+- fix: only emit `for_await_track_reactivity_loss` in async mode ([#16644](https://github.com/sveltejs/svelte/pull/16644))
+
+## 5.38.2
+
+### Patch Changes
+
+- perf: run blocks eagerly during flush instead of aborting ([#16631](https://github.com/sveltejs/svelte/pull/16631))
+
+- fix: don't clone non-proxies in `$inspect` ([#16617](https://github.com/sveltejs/svelte/pull/16617))
+
+- fix: avoid recursion error when tagging circular references ([#16622](https://github.com/sveltejs/svelte/pull/16622))
+
 ## 5.38.1
 
 ### Patch Changes

packages/svelte/messages/compile-errors/template.md

@@ -124,6 +124,49 @@
 
 > `{@const}` must be the immediate child of `{#snippet}`, `{#if}`, `{:else if}`, `{:else}`, `{#each}`, `{:then}`, `{:catch}`, `<svelte:fragment>`, `<svelte:boundary` or `<Component>`
 
+## const_tag_invalid_reference
+
+> The `{@const %name% = ...}` declaration is not available in this snippet 
+
+The following is an error:
+
+```svelte
+<svelte:boundary>
+    {@const foo = 'bar'}
+
+    {#snippet failed()}
+        {foo}
+    {/snippet}
+</svelte:boundary>
+```
+
+Here, `foo` is not available inside `failed`. The top level code inside `<svelte:boundary>` becomes part of the implicit `children` snippet, in other words the above code is equivalent to this:
+
+```svelte
+<svelte:boundary>
+    {#snippet children()}
+        {@const foo = 'bar'}
+    {/snippet}
+
+    {#snippet failed()}
+        {foo}
+    {/snippet}
+</svelte:boundary>
+```
+
+The same applies to components:
+
+```svelte
+<Component>
+    {@const foo = 'bar'}
+
+    {#snippet someProp()}
+        <!-- error -->
+        {foo}
+    {/snippet}
+</Component>
+```
+
 ## debug_tag_invalid_arguments
 
 > {@debug ...} arguments must be identifiers, not arbitrary expressions

packages/svelte/package.json

@@ -2,7 +2,7 @@
   "name": "svelte",
   "description": "Cybernetically enhanced web apps",
   "license": "MIT",
-  "version": "5.38.1",
+  "version": "5.38.3",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {

packages/svelte/src/compiler/errors.js

@@ -985,6 +985,16 @@ export function const_tag_invalid_placement(node) {
 	e(node, 'const_tag_invalid_placement', `\`{@const}\` must be the immediate child of \`{#snippet}\`, \`{#if}\`, \`{:else if}\`, \`{:else}\`, \`{#each}\`, \`{:then}\`, \`{:catch}\`, \`<svelte:fragment>\`, \`<svelte:boundary\` or \`<Component>\`\nhttps://svelte.dev/e/const_tag_invalid_placement`);
 }
 
+/**
+ * The `{@const %name% = ...}` declaration is not available in this snippet 
+ * @param {null | number | NodeLike} node
+ * @param {string} name
+ * @returns {never}
+ */
+export function const_tag_invalid_reference(node, name) {
+	e(node, 'const_tag_invalid_reference', `The \`{@const ${name} = ...}\` declaration is not available in this snippet \nhttps://svelte.dev/e/const_tag_invalid_reference`);
+}
+
 /**
  * {@debug ...} arguments must be identifiers, not arbitrary expressions
  * @param {null | number | NodeLike} node

packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js

@@ -7,6 +7,7 @@ import * as w from '../../../warnings.js';
 import { is_rune } from '../../../../utils.js';
 import { mark_subtree_dynamic } from './shared/fragment.js';
 import { get_rune } from '../../scope.js';
+import { is_component_node } from '../../nodes.js';
 
 /**
  * @param {Identifier} node
@@ -155,5 +156,37 @@ export function Identifier(node, context) {
 		) {
 			w.reactive_declaration_module_script_dependency(node);
 		}
+
+		if (binding.metadata?.is_template_declaration && context.state.options.experimental.async) {
+			let snippet_name;
+
+			// Find out if this references a {@const ...} declaration of an implicit children snippet
+			// when it is itself inside a snippet block at the same level. If so, error.
+			for (let i = context.path.length - 1; i >= 0; i--) {
+				const parent = context.path[i];
+				const grand_parent = context.path[i - 1];
+
+				if (parent.type === 'SnippetBlock') {
+					snippet_name = parent.expression.name;
+				} else if (
+					snippet_name &&
+					grand_parent &&
+					parent.type === 'Fragment' &&
+					(is_component_node(grand_parent) ||
+						(grand_parent.type === 'SvelteBoundary' &&
+							(snippet_name === 'failed' || snippet_name === 'pending')))
+				) {
+					if (
+						is_component_node(grand_parent)
+							? grand_parent.metadata.scopes.default === binding.scope
+							: context.state.scopes.get(parent) === binding.scope
+					) {
+						e.const_tag_invalid_reference(node, node.name);
+					} else {
+						break;
+					}
+				}
+			}
+		}
 	}
 }

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

@@ -359,16 +359,34 @@ export function client_component(analysis, options) {
 	if (dev) push_args.push(b.id(analysis.name));
 
 	let component_block = b.block([
+		store_init,
 		...store_setup,
 		...legacy_reactive_declarations,
-		...group_binding_declarations,
-		...state.instance_level_snippets,
-		.../** @type {ESTree.Statement[]} */ (instance.body),
-		analysis.runes || !analysis.needs_context
-			? b.empty
-			: b.stmt(b.call('$.init', analysis.immutable ? b.true : undefined))
+		...group_binding_declarations
 	]);
 
+	if (analysis.instance.has_await) {
+		const body = b.block([
+			...state.instance_level_snippets,
+			.../** @type {ESTree.Statement[]} */ (instance.body),
+			b.if(b.call('$.aborted'), b.return()),
+			.../** @type {ESTree.Statement[]} */ (template.body)
+		]);
+
+		component_block.body.push(b.stmt(b.call(`$.async_body`, b.arrow([], body, true))));
+	} else {
+		component_block.body.push(
+			...state.instance_level_snippets,
+			.../** @type {ESTree.Statement[]} */ (instance.body)
+		);
+
+		if (!analysis.runes && analysis.needs_context) {
+			component_block.body.push(b.stmt(b.call('$.init', analysis.immutable ? b.true : undefined)));
+		}
+
+		component_block.body.push(.../** @type {ESTree.Statement[]} */ (template.body));
+	}
+
 	if (analysis.needs_mutation_validation) {
 		component_block.body.unshift(
 			b.var('$$ownership_validator', b.call('$.create_ownership_validator', b.id('$$props')))
@@ -389,41 +407,6 @@ export function client_component(analysis, options) {
 		analysis.uses_slots ||
 		analysis.slot_names.size > 0;
 
-	if (analysis.instance.has_await) {
-		const params = [b.id('$$anchor')];
-		if (should_inject_props) {
-			params.push(b.id('$$props'));
-		}
-		if (store_setup.length > 0) {
-			params.push(b.id('$$stores'));
-		}
-		const body = b.function_declaration(
-			b.id('$$body'),
-			params,
-			b.block([
-				b.var('$$unsuspend', b.call('$.suspend')),
-				...component_block.body,
-				b.if(b.call('$.aborted'), b.return()),
-				.../** @type {ESTree.Statement[]} */ (template.body),
-				b.stmt(b.call('$$unsuspend'))
-			]),
-			true
-		);
-
-		state.hoisted.push(body);
-
-		component_block = b.block([
-			b.var('fragment', b.call('$.comment')),
-			b.var('node', b.call('$.first_child', b.id('fragment'))),
-			store_init,
-			b.stmt(b.call(body.id, b.id('node'), ...params.slice(1))),
-			b.stmt(b.call('$.append', b.id('$$anchor'), b.id('fragment')))
-		]);
-	} else {
-		component_block.body.unshift(store_init);
-		component_block.body.push(.../** @type {ESTree.Statement[]} */ (template.body));
-	}
-
 	// trick esrap into including comments
 	component_block.loc = instance.loc;
 

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

@@ -8,7 +8,12 @@ import { dev, is_ignored } from '../../../../state.js';
  * @param {ComponentContext} context
  */
 export function ForOfStatement(node, context) {
-	if (node.await && dev && !is_ignored(node, 'await_reactivity_loss')) {
+	if (
+		node.await &&
+		dev &&
+		!is_ignored(node, 'await_reactivity_loss') &&
+		context.state.options.experimental.async
+	) {
 		const left = /** @type {VariableDeclaration | Pattern} */ (context.visit(node.left));
 		const argument = /** @type {Expression} */ (context.visit(node.right));
 		const body = /** @type {Statement} */ (context.visit(node.body));