fix(optimize-deps): avoid "unsupported" warnings for browser:false mappings

packages/vite/src/node/optimizer/rolldownDepPlugin.ts

@@ -1,7 +1,7 @@
 import path from 'node:path'
 import MagicString from 'magic-string'
 import type { ImportKind, Plugin, RolldownPlugin } from 'rolldown'
-import { prefixRegex } from 'rolldown/filter'
+import { exactRegex, prefixRegex } from 'rolldown/filter'
 import { stripLiteral } from 'strip-literal'
 import { isWindows } from '../../shared/utils'
 import { JS_TYPES_RE, KNOWN_ASSET_TYPES } from '../constants'
@@ -121,6 +121,11 @@ export function rolldownDepPlugin(
   }
 
   const resolveResult = (id: string, resolved: string, kind: ImportKind) => {
+    // An exact browser-external id is an explicit browser:false mapping.
+    // Suffixed ids are unsupported Node builtins and still need the warning.
+    if (resolved === browserExternalId) {
+      return { id: browserExternalId }
+    }
     if (resolved.startsWith(browserExternalId)) {
       return {
         id: browserExternalNamespace + id,
@@ -255,11 +260,15 @@ export function rolldownDepPlugin(
       load: {
         filter: {
           id: [
+            exactRegex(browserExternalId),
             prefixRegex(browserExternalNamespace),
             prefixRegex(optionalPeerDepNamespace),
           ],
         },
         handler(id) {
+          if (id === browserExternalId) {
+            return { code: 'module.exports = {}' }
+          }
           if (id.startsWith(browserExternalNamespace)) {
             const path = id.slice(browserExternalNamespace.length)
             if (isProduction) {

playground/optimize-deps/__tests__/optimize-deps.spec.ts

@@ -255,6 +255,20 @@ test('non optimized module is not duplicated', async () => {
     .toBe('from-absolute-path, from-relative-path')
 })
 
+test.runIf(isServe)(
+  'optimized browser:false is empty without warning',
+  async () => {
+    expect(await page.textContent('.browser-false-optimized')).toBe('[success]')
+    expect(browserLogs).not.toEqual(
+      expect.arrayContaining([
+        expect.stringContaining(
+          'Module "browser-false-only" has been externalized for browser compatibility',
+        ),
+      ]),
+    )
+  },
+)
+
 test.runIf(isServe)('error on builtin modules usage', () => {
   expect(browserLogs).toEqual(
     expect.arrayContaining([

playground/optimize-deps/dep-browser-false/index.js

@@ -0,0 +1,4 @@
+// An explicit browser:false mapping is an empty module, not a Node builtin warning.
+// eslint-disable-next-line n/no-missing-require -- mapped to false by package browser field
+const fs = require('browser-false-only')
+module.exports = fs.readFileSync === undefined ? '[success]' : '[fail]'

playground/optimize-deps/dep-browser-false/package.json

@@ -0,0 +1,9 @@
+{
+  "name": "@vitejs/test-dep-browser-false",
+  "private": true,
+  "version": "0.0.0",
+  "main": "index.js",
+  "browser": {
+    "browser-false-only": false
+  }
+}

playground/optimize-deps/index.html

@@ -336,6 +336,12 @@ <h2>Import the CommonJS external package that omits the js suffix</h2>
   }
 </script>
 
+<p class="browser-false-optimized">[pending]</p>
+<script type="module">
+  import browserFalse from '@vitejs/test-dep-browser-false'
+  text('.browser-false-optimized', browserFalse)
+</script>
+
 <script type="module">
   // should error on builtin modules from dep
   import { read } from '@vitejs/test-dep-with-builtin-module-cjs'

playground/optimize-deps/package.json

@@ -39,6 +39,7 @@
     "@vitejs/test-dep-with-asset-ext1.pdf": "file:./dep-with-asset-ext/dep1",
     "@vitejs/test-dep-with-asset-ext2.pdf": "file:./dep-with-asset-ext/dep2",
     "@vitejs/test-dep-with-builtin-module-cjs": "file:./dep-with-builtin-module-cjs",
+    "@vitejs/test-dep-browser-false": "file:./dep-browser-false",
     "@vitejs/test-dep-with-builtin-module-esm": "file:./dep-with-builtin-module-esm",
     "@vitejs/test-dep-with-dynamic-import": "file:./dep-with-dynamic-import",
     "@vitejs/test-dep-with-optional-peer-dep": "file:./dep-with-optional-peer-dep",