Merge branch 'main' into new-spring

Author: dummdidumm

.changeset/wild-islands-help.md

@@ -246,6 +246,23 @@ We can tighten things up further by declaring a generic, so that `data` and `row
 </script>
 ```
 
+## Exporting snippets
+
+Snippets declared at the top level of a `.svelte` file can be exported from a `<script module>` for use in other components, provided they don't reference any declarations in a non-module `<script>` (whether directly or indirectly, via other snippets) ([demo](/playground/untitled#H4sIAAAAAAAAE3WPwY7CMAxEf8UyB1hRgdhjl13Bga8gHFJipEqtGyUGFUX5dxJUtEB3b9bYM_MckHVLWOKut50TMuC5tpbEY4GnuiGP5T6gXG0-ykLSB8vW2oW_UCNZq7Snv_Rjx0Kc4kpc-6OrrfwoVlK3uQ4CaGMgwsl1LUwXy0f54J9-KV4vf20cNo7YkMu22aqAz4-oOLUI9YKluDPF4h_at-hX5PFyzA1tZ84N3fGpf8YfUU6GvDumLqDKmEqCjjCHUEX4hqDTWCU5PJ6Or38c4g1cPu9tnAEAAA==)):
+
+```svelte
+<script module>
+	export { add };
+</script>
+
+{#snippet add(a, b)}
+	{a} + {b} = {a + b}
+{/snippet}
+```
+
+> [!NOTE]
+> This requires Svelte 5.5.0 or newer
+
 ## Programmatic snippets
 
 Snippets can be created programmatically with the [`createRawSnippet`](svelte#createRawSnippet) API. This is intended for advanced use cases.

documentation/docs/03-template-syntax/06-snippet.md

@@ -40,26 +40,26 @@ If you want to use one of these features, you need to setup up a `script` prepro
 
 To use non-type-only TypeScript features within Svelte components, you need to add a preprocessor that will turn TypeScript into JavaScript.
 
-### Using SvelteKit or Vite
-
-The easiest way to get started is scaffolding a new SvelteKit project by typing `npx sv create`, following the prompts and choosing the TypeScript option.
-
 ```ts
 /// file: svelte.config.js
 // @noErrors
-import { vitePreprocess } from '@sveltejs/kit/vite';
+import { vitePreprocess } from '@sveltejs/vite-plugin-svelte';
 
 const config = {
-	preprocess: vitePreprocess()
+	// Note the additional `{ script: true }`
+	preprocess: vitePreprocess({ script: true })
 };
 
 export default config;
 ```
 
-If you don't need or want all the features SvelteKit has to offer, you can scaffold a Svelte-flavoured Vite project instead by typing `npm create vite@latest` and selecting the `svelte-ts` option.
+### Using SvelteKit or Vite
+
+The easiest way to get started is scaffolding a new SvelteKit project by typing `npx sv create`, following the prompts and choosing the TypeScript option.
 
 ```ts
 /// file: svelte.config.js
+// @noErrors
 import { vitePreprocess } from '@sveltejs/vite-plugin-svelte';
 
 const config = {
@@ -69,6 +69,8 @@ const config = {
 export default config;
 ```
 
+If you don't need or want all the features SvelteKit has to offer, you can scaffold a Svelte-flavoured Vite project instead by typing `npm create vite@latest` and selecting the `svelte-ts` option.
+
 In both cases, a `svelte.config.js` with `vitePreprocess` will be added. Vite/SvelteKit will read from this config file.
 
 ### Other build tools
@@ -77,6 +79,14 @@ If you're using tools like Rollup or Webpack instead, install their respective S
 
 > [!NOTE] If you're starting a new project, we recommend using SvelteKit or Vite instead
 
+## tsconfig.json settings
+
+When using TypeScript, make sure your `tsconfig.json` is setup correctly.
+
+- Use a [`target`](https://www.typescriptlang.org/tsconfig/#target) of at least `ES2022`, or a `target` of at least `ES2015` alongside [`useDefineForClassFields`](https://www.typescriptlang.org/tsconfig/#useDefineForClassFields). This ensures that rune declarations on class fields are not messed with, which would break the Svelte compiler
+- Set [`verbatimModuleSyntax`](https://www.typescriptlang.org/tsconfig/#verbatimModuleSyntax) to `true` so that imports are left as-is
+- Set [`isolatedModules`](https://www.typescriptlang.org/tsconfig/#isolatedModules) to `true` so that each file is looked at in isolation. TypeScript has a few features which require cross-file analysis and compilation, which the Svelte compiler and tooling like Vite don't do. 
+
 ## Typing `$props`
 
 Type `$props` just like a regular object with certain properties.

documentation/docs/07-misc/03-typescript.md

@@ -400,6 +400,12 @@ Expected token %token%
 Expected whitespace
 ```
 
+### export_undefined
+
+```
+`%name%` is not defined
+```
+
 ### global_reference_invalid
 
 ```
@@ -694,6 +700,30 @@ Cannot use `<slot>` syntax and `{@render ...}` tags in the same component. Migra
 Cannot use explicit children snippet at the same time as implicit children content. Remove either the non-whitespace content or the children snippet block
 ```
 
+### snippet_invalid_export
+
+```
+An exported snippet can only reference things declared in a `<script module>`, or other exportable snippets
+```
+
+It's possible to export a snippet from a `<script module>` block, but only if it doesn't reference anything defined inside a non-module-level `<script>`. For example you can't do this...
+
+```svelte
+<script module>
+	export { greeting };
+</script>
+
+<script>
+	let message = 'hello';
+</script>
+
+{#snippet greeting(name)}
+	<p>{message} {name}!</p>
+{/snippet}
+```
+
+...because `greeting` references `message`, which is defined in the second `<script>`.
+
 ### snippet_invalid_rest_parameter
 
 ```

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

@@ -1,5 +1,15 @@
 # svelte
 
+## 5.5.0
+
+### Minor Changes
+
+- feat: allow snippets to be exported from module scripts ([#14315](https://github.com/sveltejs/svelte/pull/14315))
+
+### Patch Changes
+
+- fix: ignore TypeScript generics on variables ([#14509](https://github.com/sveltejs/svelte/pull/14509))
+
 ## 5.4.0
 
 ### Minor Changes

packages/svelte/CHANGELOG.md

@@ -38,6 +38,10 @@
 
 > `$effect()` can only be used as an expression statement
 
+## export_undefined
+
+> `%name%` is not defined
+
 ## global_reference_invalid
 
 > `%name%` is an illegal variable name. To reference a global variable called `%name%`, use `globalThis.%name%`
@@ -134,6 +138,28 @@
 
 > %name% cannot be used in runes mode
 
+## snippet_invalid_export
+
+> An exported snippet can only reference things declared in a `<script module>`, or other exportable snippets
+
+It's possible to export a snippet from a `<script module>` block, but only if it doesn't reference anything defined inside a non-module-level `<script>`. For example you can't do this...
+
+```svelte
+<script module>
+	export { greeting };
+</script>
+
+<script>
+	let message = 'hello';
+</script>
+
+{#snippet greeting(name)}
+	<p>{message} {name}!</p>
+{/snippet}
+```
+
+...because `greeting` references `message`, which is defined in the second `<script>`.
+
 ## snippet_parameter_assignment
 
 > Cannot reassign or bind to snippet parameter

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

@@ -2,7 +2,7 @@
   "name": "svelte",
   "description": "Cybernetically enhanced web apps",
   "license": "MIT",
-  "version": "5.4.0",
+  "version": "5.5.0",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {

packages/svelte/package.json

@@ -168,6 +168,16 @@ export function effect_invalid_placement(node) {
 	e(node, "effect_invalid_placement", "`$effect()` can only be used as an expression statement");
 }
 
+/**
+ * `%name%` is not defined
+ * @param {null | number | NodeLike} node
+ * @param {string} name
+ * @returns {never}
+ */
+export function export_undefined(node, name) {
+	e(node, "export_undefined", `\`${name}\` is not defined`);
+}
+
 /**
  * `%name%` is an illegal variable name. To reference a global variable called `%name%`, use `globalThis.%name%`
  * @param {null | number | NodeLike} node
@@ -395,6 +405,15 @@ export function runes_mode_invalid_import(node, name) {
 	e(node, "runes_mode_invalid_import", `${name} cannot be used in runes mode`);
 }
 
+/**
+ * An exported snippet can only reference things declared in a `<script module>`, or other exportable snippets
+ * @param {null | number | NodeLike} node
+ * @returns {never}
+ */
+export function snippet_invalid_export(node) {
+	e(node, "snippet_invalid_export", "An exported snippet can only reference things declared in a `<script module>`, or other exportable snippets");
+}
+
 /**
  * Cannot reassign or bind to snippet parameter
  * @param {null | number | NodeLike} node

packages/svelte/src/compiler/errors.js

@@ -10,17 +10,43 @@ const ParserWithTS = acorn.Parser.extend(tsPlugin({ allowSatisfies: true }));
 /**
  * @param {string} source
  * @param {boolean} typescript
+ * @param {boolean} [is_script]
  */
-export function parse(source, typescript) {
+export function parse(source, typescript, is_script) {
 	const parser = typescript ? ParserWithTS : acorn.Parser;
 	const { onComment, add_comments } = get_comment_handlers(source);
-
-	const ast = parser.parse(source, {
-		onComment,
-		sourceType: 'module',
-		ecmaVersion: 13,
-		locations: true
-	});
+	// @ts-ignore
+	const parse_statement = parser.prototype.parseStatement;
+
+	// If we're dealing with a <script> then it might contain an export
+	// for something that doesn't exist directly inside but is inside the
+	// component instead, so we need to ensure that Acorn doesn't throw
+	// an error in these cases
+	if (is_script) {
+		// @ts-ignore
+		parser.prototype.parseStatement = function (...args) {
+			const v = parse_statement.call(this, ...args);
+			// @ts-ignore
+			this.undefinedExports = {};
+			return v;
+		};
+	}
+
+	let ast;
+
+	try {
+		ast = parser.parse(source, {
+			onComment,
+			sourceType: 'module',
+			ecmaVersion: 13,
+			locations: true
+		});
+	} finally {
+		if (is_script) {
+			// @ts-ignore
+			parser.prototype.parseStatement = parse_statement;
+		}
+	}
 
 	if (typescript) amend(source, ast);
 	add_comments(ast);

packages/svelte/src/compiler/phases/1-parse/acorn.js

@@ -34,7 +34,7 @@ export function read_script(parser, start, attributes) {
 	let ast;
 
 	try {
-		ast = acorn.parse(source, parser.ts);
+		ast = acorn.parse(source, parser.ts, true);
 	} catch (err) {
 		parser.acorn_error(err);
 	}

packages/svelte/src/compiler/phases/1-parse/read/script.js

@@ -325,6 +325,7 @@ function open(parser) {
 			parameters: function_expression.params,
 			body: create_fragment(),
 			metadata: {
+				can_hoist: false,
 				sites: new Set()
 			}
 		});

packages/svelte/src/compiler/phases/1-parse/state/tag.js

@@ -429,7 +429,6 @@ export function analyze_component(root, source, options) {
 		reactive_statements: new Map(),
 		binding_groups: new Map(),
 		slot_names: new Map(),
-		top_level_snippets: [],
 		css: {
 			ast: root.css,
 			hash: root.css
@@ -443,6 +442,7 @@ export function analyze_component(root, source, options) {
 			keyframes: []
 		},
 		source,
+		undefined_exports: new Map(),
 		snippet_renderers: new Map(),
 		snippets: new Set()
 	};
@@ -697,6 +697,17 @@ export function analyze_component(root, source, options) {
 		analysis.reactive_statements = order_reactive_statements(analysis.reactive_statements);
 	}
 
+	for (const node of analysis.module.ast.body) {
+		if (node.type === 'ExportNamedDeclaration' && node.specifiers !== null) {
+			for (const specifier of node.specifiers) {
+				if (specifier.local.type !== 'Identifier') continue;
+
+				const binding = analysis.module.scope.get(specifier.local.name);
+				if (!binding) e.export_undefined(specifier, specifier.local.name);
+			}
+		}
+	}
+
 	if (analysis.event_directive_node && analysis.uses_event_attributes) {
 		e.mixed_event_handler_syntaxes(
 			analysis.event_directive_node,