chore: migrate to rolldown

documentation/docs/07-misc/.generated/browser-support-features.md

@@ -3,5 +3,8 @@
 | Feature | Chrome/Edge | Firefox | Safari |
 | - | - | - | - |
 | [`$state.snapshot`](/docs/svelte/$state#$state.snapshot) | 98 | 94 | 15.4 |
+| [`bind:borderBoxSize`](/TODO) | <span style="color: var(--sk-fg-4)">—</span> | 93 | not supported |
+| [`bind:contentBoxSize`](/TODO) | <span style="color: var(--sk-fg-4)">—</span> | 93 | not supported |
+| [`bind:contentRect`](/TODO) | <span style="color: var(--sk-fg-4)">—</span> | 93 | not supported |
 | [`bind:devicePixelContentBoxSize`](/docs/svelte/bind#Dimensions) | <span style="color: var(--sk-fg-4)">—</span> | 93 | not supported |
 | [`flip` from `svelte/animate`](/docs/svelte/svelte-animate#flip) | <span style="color: var(--sk-fg-4)">—</span> | 126 | <span style="color: var(--sk-fg-4)">—</span> |

packages/svelte/package.json

@@ -138,8 +138,8 @@
     "templating"
   ],
   "scripts": {
-    "build": "rollup -c && pnpm generate && node scripts/check-treeshakeability.js",
-    "dev": "node scripts/process-messages -w & rollup -cw",
+    "build": "rolldown -c && pnpm generate && node scripts/check-treeshakeability.js",
+    "dev": "node scripts/process-messages -w & rolldown -cw",
     "check": "tsc --project tsconfig.runtime.json && tsc && cd ./tests/types && tsc",
     "check:tsgo": "tsgo --project tsconfig.runtime.json --skipLibCheck && tsgo --skipLibCheck",
     "check:watch": "tsc --watch",
@@ -153,16 +153,12 @@
   "devDependencies": {
     "@jridgewell/trace-mapping": "^0.3.25",
     "@playwright/test": "^1.60.0",
-    "@rollup/plugin-commonjs": "^28.0.1",
-    "@rollup/plugin-node-resolve": "^15.3.0",
-    "@rollup/plugin-terser": "^0.4.4",
-    "@rollup/plugin-virtual": "^3.0.2",
     "@types/aria-query": "^5.0.4",
     "@types/node": "^20.11.5",
     "baseline-browser-mapping": "^2.10.32",
     "dts-buddy": "^0.5.5",
     "esbuild": "^0.25.10",
-    "rollup": "^4.59.0",
+    "rolldown": "^1.0.3",
     "source-map": "^0.7.4",
     "tinyglobby": "^0.2.12",
     "typescript": "^5.5.4",

packages/svelte/rolldown.config.js

@@ -1,7 +1,4 @@
-import commonjs from '@rollup/plugin-commonjs';
-import resolve from '@rollup/plugin-node-resolve';
-import terser from '@rollup/plugin-terser';
-import { defineConfig } from 'rollup';
+import { defineConfig } from 'rolldown';
 
 // runs the version generation as a side-effect of importing
 import './scripts/generate-version.js';
@@ -12,6 +9,5 @@ export default defineConfig({
 		file: 'compiler/index.js',
 		format: 'umd',
 		name: 'svelte'
-	},
-	plugins: [resolve(), commonjs(), terser()]
+	}
 });

packages/svelte/scripts/check-treeshakeability.js

@@ -1,16 +1,15 @@
 import fs from 'node:fs';
 import path from 'node:path';
 import process from 'node:process';
-import { rollup } from 'rollup';
-import virtual from '@rollup/plugin-virtual';
-import { nodeResolve } from '@rollup/plugin-node-resolve';
+import { rolldown } from 'rolldown';
+import { virtual } from './virtual.js';
 import { compile } from 'svelte/compiler';
 
 /**
  * @param {string} entry
  */
 async function bundle_code(entry) {
-	const bundle = await rollup({
+	const bundle = await rolldown({
 		input: '__entry__',
 		plugins: [
 			virtual({
@@ -24,10 +23,7 @@ async function bundle_code(entry) {
 						return path.resolve(entry.browser ?? entry.default);
 					}
 				}
-			},
-			nodeResolve({
-				exportConditions: ['production', 'import', 'browser', 'default']
-			})
+			}
 		],
 		onwarn: (warning, handle) => {
 			if (warning.code !== 'EMPTY_BUNDLE' && warning.code !== 'CIRCULAR_DEPENDENCY') {

packages/svelte/scripts/generate-browser-support.ts

@@ -24,9 +24,8 @@ import fs from 'node:fs';
 import path from 'node:path';
 import process from 'node:process';
 import { fileURLToPath } from 'node:url';
-import { rollup, type OutputChunk } from 'rollup';
-import virtual from '@rollup/plugin-virtual';
-import { nodeResolve } from '@rollup/plugin-node-resolve';
+import { rolldown, type OutputChunk } from 'rolldown';
+import { virtual } from './virtual.js';
 import { getCompatibleVersions } from 'baseline-browser-mapping';
 import {
 	detect_features,
@@ -54,6 +53,9 @@ type ConditionalRow = {
 
 const doc_links: Record<string, string | null> = {
 	'`$state.snapshot`': '/docs/svelte/$state#$state.snapshot',
+	'`bind:contentRect`': '/TODO',
+	'`bind:contentBoxSize`': '/TODO',
+	'`bind:borderBoxSize`': '/TODO',
 	'`bind:devicePixelContentBoxSize`': '/docs/svelte/bind#Dimensions',
 	'`flip` from `svelte/animate`': '/docs/svelte/svelte-animate#flip'
 };
@@ -286,11 +288,11 @@ function safe_name(importee: string): string {
  *
  * `entry_code` is virtual module source: typically `export * from
  * 'svelte/...'` for a runtime entry, or compiled fixture JS for a per-feature
- * scan. `silent` suppresses rollup's circular-dependency warnings — used for
+ * scan. `silent` suppresses rolldown's circular-dependency warnings — used for
  * fixture bundles where they're known and noisy.
  */
 async function bundle(entry_code: string, options: { silent?: boolean } = {}): Promise<string> {
-	const built = await rollup({
+	const built = await rolldown({
 		input: '__entry__',
 		plugins: [
 			virtual({ __entry__: entry_code }),
@@ -305,8 +307,7 @@ async function bundle(entry_code: string, options: { silent?: boolean } = {}): P
 						if (file) return path.resolve(pkg_dir, file);
 					}
 				}
-			},
-			nodeResolve({ exportConditions: ['production', 'import', 'browser', 'default'] })
+			}
 		],
 		// Treat optional peers / Node-only branches as external so we only scan
 		// code that actually runs in the browser.

packages/svelte/scripts/virtual.js

@@ -0,0 +1,18 @@
+/**
+ *
+ * @param {Record<string, string>} modules
+ * @returns {import('rolldown').Plugin}
+ */
+export function virtual(modules) {
+	const resolved_ids = new Map(Object.entries(modules).map(([id, code]) => ['\0' + id, code]));
+
+	return {
+		name: 'virtual',
+		resolveId(id) {
+			if (id in modules) return '\0' + id;
+		},
+		load(id) {
+			return resolved_ids.get(id) ?? null;
+		}
+	};
+}

packages/svelte/src/internal/server/render-context.js

@@ -78,7 +78,7 @@ export function init_render_context() {
 	return als_import;
 }
 
-// this has to be a function because rollup won't treeshake it if it's a constant
+// this has to be a function because rolldown won't treeshake it if it's a constant
 function in_webcontainer() {
 	// @ts-ignore -- this will fail when we run typecheck because we exclude node types
 	// eslint-disable-next-line n/prefer-global/process

playgrounds/sandbox/package.json

@@ -21,7 +21,7 @@
     "polka": "^1.0.0-next.25",
     "svelte": "workspace:*",
     "tinyglobby": "^0.2.12",
-    "vite": "^7.3.2",
+    "vite": "^8.0.16",
     "vite-plugin-devtools-json": "^1.0.0",
     "vite-plugin-inspect": "^11.3.3"
   }