refactor: use svelte 5.26 hasGlobal flag instead of custom impl

Author: dominikg

packages/vite-plugin-svelte/src/index.js

@@ -118,20 +118,16 @@ export function svelte(inlineOptions) {
 						};
 					} else {
 						if (query.svelte && query.type === 'style') {
-							// @ts-expect-error __meta does not exist
-							const { __meta, ...css } = cache.getCSS(svelteRequest);
-							if (css) {
-								if (__meta?.hasUnscopedGlobalCss) {
-									return css; // css contains unscoped global, do not scope to component
+							const cachedCss = cache.getCSS(svelteRequest);
+							if (cachedCss) {
+								const { hasGlobal, ...css } = cachedCss;
+								if (hasGlobal === false) {
+									// hasGlobal was added in svelte 5.26.0, so make sure it is boolean false
+									css.meta ??= {};
+									css.meta.vite ??= {};
+									css.meta.vite.cssScopeTo = [svelteRequest.filename, 'default'];
 								}
-								return {
-									...css,
-									meta: {
-										vite: {
-											cssScopeTo: [svelteRequest.filename, 'default']
-										}
-									}
-								};
+								return css;
 							}
 						}
 						// prevent vite asset plugin from loading files as url that should be compiled in transform

packages/vite-plugin-svelte/src/types/compile.d.ts

@@ -1,6 +1,7 @@
 import type { Processed, CompileResult } from 'svelte/compiler';
 import type { SvelteRequest } from './id.d.ts';
 import type { ResolvedOptions } from './options.d.ts';
+import type { CustomPluginOptionsVite } from 'vite';
 
 export type CompileSvelte = (
 	svelteRequest: SvelteRequest,
@@ -12,8 +13,9 @@ export interface Code {
 	code: string;
 	map?: any;
 	dependencies?: any[];
-	__meta?: {
-		hasUnscopedGlobalCss?: boolean;
+	hasGlobal?: boolean;
+	meta?: {
+		vite?: CustomPluginOptionsVite;
 	};
 }
 

packages/vite-plugin-svelte/src/utils/compile.js

@@ -68,7 +68,7 @@ export function createCompileSvelte() {
 		}
 
 		let preprocessed;
-		let hasUnscopedGlobalCss = false;
+
 		const preprocessors = options.preprocess
 			? Array.isArray(options.preprocess)
 				? [...options.preprocess]
@@ -80,17 +80,6 @@ export function createCompileSvelte() {
 			preprocessors.push(devStylePreprocessor);
 		}
 
-		if (options.emitCss) {
-			// check if css has unscoped global rules
-			// This is later used to decide if css output can be scoped to the js module for treeshaking
-			preprocessors.push({
-				name: 'test-has-global-style',
-				style({ content }) {
-					hasUnscopedGlobalCss = /(?:^|,)\s*(?::global[\s{(]|@keyframes -global-)/m.test(content);
-				}
-			});
-		}
-
 		if (preprocessors.length > 0) {
 			try {
 				preprocessed = await svelte.preprocess(code, preprocessors, { filename }); // full filename here so postcss works
@@ -145,15 +134,6 @@ export function createCompileSvelte() {
 		try {
 			compiled = svelte.compile(finalCode, { ...finalCompileOptions, filename });
 
-			if (compiled.css && hasUnscopedGlobalCss) {
-				Object.defineProperty(compiled.css, '__meta', {
-					value: { hasUnscopedGlobalCss },
-					writable: false,
-					enumerable: false,
-					configurable: false
-				});
-			}
-
 			// patch output with partial accept until svelte does it
 			// TODO remove later
 			if (