parametric runes

packages/svelte/src/compiler/index.js

@@ -34,7 +34,8 @@ export function compile(source, options) {
 	const combined_options = {
 		...validated,
 		...parsed_options,
-		customElementOptions
+		customElementOptions,
+		runes: 'runes' in parsed_options ? () => parsed_options.runes : validated.runes
 	};
 
 	if (parsed.metadata.ts) {

packages/svelte/src/compiler/migrate/index.js

@@ -142,10 +142,11 @@ export function migrate(source, { filename, use_ts } = {}) {
 
 		/** @type {ValidatedCompileOptions} */
 		const combined_options = {
-			...validate_component_options({}, ''),
+			...validate_component_options({}),
 			...parsed_options,
 			customElementOptions,
 			filename: filename ?? UNKNOWN_FILENAME,
+			runes: 'runes' in parsed_options ? () => parsed_options.runes : () => undefined,
 			experimental: {
 				async: true
 			}

packages/svelte/src/compiler/phases/2-analyze/index.js

@@ -345,6 +345,8 @@ export function analyze_component(root, source, options) {
 
 	let synthetic_stores_legacy_check = [];
 
+	const runes_option = options.runes?.({ filename: options.filename });
+
 	// create synthetic bindings for store subscriptions
 	for (const [name, references] of module.scope.references) {
 		if (name[0] !== '$' || RESERVED.includes(name)) continue;
@@ -359,7 +361,7 @@ export function analyze_component(root, source, options) {
 		// If we're not in legacy mode through the compiler option, assume the user
 		// is referencing a rune and not a global store.
 		if (
-			options.runes === false ||
+			runes_option === false ||
 			!is_rune(name) ||
 			(declaration !== null &&
 				// const state = $state(0) is valid
@@ -395,7 +397,7 @@ export function analyze_component(root, source, options) {
 				e.store_invalid_scoped_subscription(is_nested_store_subscription_node);
 			}
 
-			if (options.runes !== false) {
+			if (runes_option !== false) {
 				if (declaration === null && /[a-z]/.test(store_name[0])) {
 					e.global_reference_invalid(references[0].node, name);
 				} else if (declaration !== null && is_rune(name)) {
@@ -447,7 +449,7 @@ export function analyze_component(root, source, options) {
 	const component_name = get_component_name(options.filename);
 
 	const runes =
-		options.runes ??
+		runes_option ??
 		(has_await || instance.has_await || Array.from(module.scope.references.keys()).some(is_rune));
 
 	if (!runes) {
@@ -491,7 +493,7 @@ export function analyze_component(root, source, options) {
 		maybe_runes:
 			!runes &&
 			// if they explicitly disabled runes, use the legacy behavior
-			options.runes !== false &&
+			runes_option !== false &&
 			![...module.scope.references.keys()].some((name) =>
 				['$$props', '$$restProps'].includes(name)
 			) &&

packages/svelte/src/compiler/types/index.d.ts

@@ -142,7 +142,7 @@ export interface CompileOptions extends ModuleCompileOptions {
 	 * which is likely not what you want. If you're using Vite, consider using [dynamicCompileOptions](https://github.com/sveltejs/vite-plugin-svelte/blob/main/docs/config.md#dynamiccompileoptions) instead.
 	 * @default undefined
 	 */
-	runes?: boolean | undefined;
+	runes?: boolean | undefined | ((options: { filename: string }) => boolean | undefined);
 	/**
 	 *  If `true`, exposes the Svelte major version in the browser by adding it to a `Set` stored in the global `window.__svelte.v`.
 	 *
@@ -259,7 +259,7 @@ export type ValidatedCompileOptions = ValidatedModuleCompileOptions &
 		cssOutputFilename: CompileOptions['cssOutputFilename'];
 		sourcemap: CompileOptions['sourcemap'];
 		compatibility: Required<Required<CompileOptions>['compatibility']>;
-		runes: CompileOptions['runes'];
+		runes: (options: { filename: string }) => boolean | undefined;
 		customElementOptions: AST.SvelteOptions['customElement'];
 		hmr: CompileOptions['hmr'];
 	};

packages/svelte/src/compiler/validate-options.js

@@ -1,6 +1,6 @@
 /** @import { Validator } from '@sveltejs/config/validate' */
 /** @import { ModuleCompileOptions, ValidatedModuleCompileOptions, CompileOptions, ValidatedCompileOptions } from '#compiler' */
-import { string, boolean, object, validator, ValidateError } from '@sveltejs/config/validate';
+import { string, boolean, object, fn, validator, ValidateError } from '@sveltejs/config/validate';
 import * as e from './errors.js';
 import * as w from './warnings.js';
 
@@ -37,7 +37,7 @@ const common_options = {
 		return /** @type {'client' | 'server' | false} */ (input);
 	}),
 
-	warningFilter: fun(() => true),
+	warningFilter: fn(() => true),
 
 	experimental: object({
 		async: boolean(false)
@@ -67,7 +67,7 @@ const component_options = {
 		return input;
 	}),
 
-	cssHash: fun(({ css, filename, hash }) => {
+	cssHash: fn(({ css, filename, hash }) => {
 		return `svelte-${hash(filename === '(unknown)' ? css : filename ?? css)}`;
 	}),
 
@@ -104,7 +104,8 @@ const component_options = {
 
 	preserveWhitespace: boolean(false),
 
-	runes: boolean(undefined),
+	/** @type {Validator<boolean | undefined | () => boolean | undefined, () => boolean | undefined>} */
+	runes: parametric(() => /** @type {boolean | undefined} */ (undefined)),
 
 	hmr: boolean(false),
 
@@ -261,15 +262,20 @@ function list(options, fallback = options[0]) {
 }
 
 /**
- * @param {(...args: any) => any} fallback
- * @returns {Validator<(...args: any) => any>}
+ * @template {(...args: any[]) => any} F
+ * @param {F} fallback
+ * @returns {Validator<ReturnType<F> | F, F>}
  */
-function fun(fallback) {
-	return validator(fallback, (input, keypath) => {
-		if (typeof input !== 'function') {
-			throw_error(`${keypath} should be a function, if specified`);
+function parametric(fallback) {
+	return validator(fallback, (input) => {
+		if (typeof input === 'function') {
+			return /** @type {F} */ (input);
 		}
-		return input;
+
+		/** @type {(...args: Parameters<F>) => ReturnType<F>} */
+		const normalized = (..._args) => /** @type {ReturnType<F>} */ (input);
+
+		return /** @type {F} */ (/** @type {unknown} */ (normalized));
 	});
 }