From fd030aea79caa116d40f3c6f2990d0b9b15b9784 Mon Sep 17 00:00:00 2001
From: Qiu Guanzong <gavinyau@connect.hku.hk>
Date: Sun, 20 Sep 2026 20:25:06 +0800
Subject: [PATCH] fix(optimizer): avoid false-mapping warnings (fix #23512)

---
 .../vite/src/node/optimizer/rolldownDepPlugin.ts    | 12 ++++++++++++
 .../optimize-deps/__tests__/optimize-deps.spec.ts   | 13 +++++++++++++
 .../dep-cjs-browser-field-bare/internal.js          |  5 ++++-
 .../dep-cjs-browser-field-bare/package.json         |  3 ++-
 4 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/packages/vite/src/node/optimizer/rolldownDepPlugin.ts b/packages/vite/src/node/optimizer/rolldownDepPlugin.ts
index 07d8cab4566b40..c2953036732d34 100644
--- a/packages/vite/src/node/optimizer/rolldownDepPlugin.ts
+++ b/packages/vite/src/node/optimizer/rolldownDepPlugin.ts
@@ -58,6 +58,7 @@ const externalTypes = [
 
 const optionalPeerDepNamespace = 'optional-peer-dep:'
 const browserExternalNamespace = 'browser-external:'
+const browserExternalEmptyNamespace = `${browserExternalNamespace}empty:`
 
 export function rolldownDepPlugin(
   environment: Environment,
@@ -121,6 +122,11 @@ export function rolldownDepPlugin(
   }
 
   const resolveResult = (id: string, resolved: string, kind: ImportKind) => {
+    if (resolved === browserExternalId) {
+      return {
+        id: browserExternalEmptyNamespace + id,
+      }
+    }
     if (resolved.startsWith(browserExternalId)) {
       return {
         id: browserExternalNamespace + id,
@@ -260,6 +266,12 @@ export function rolldownDepPlugin(
           ],
         },
         handler(id) {
+          if (id.startsWith(browserExternalEmptyNamespace)) {
+            return {
+              code: 'module.exports = {}',
+            }
+          }
+
           if (id.startsWith(browserExternalNamespace)) {
             const path = id.slice(browserExternalNamespace.length)
             if (isProduction) {
diff --git a/playground/optimize-deps/__tests__/optimize-deps.spec.ts b/playground/optimize-deps/__tests__/optimize-deps.spec.ts
index d6febaafad2c17..eb856425269df1 100644
--- a/playground/optimize-deps/__tests__/optimize-deps.spec.ts
+++ b/playground/optimize-deps/__tests__/optimize-deps.spec.ts
@@ -116,6 +116,19 @@ test('cjs browser field bare', async () => {
     .toBe('pong')
 })
 
+test.runIf(isServe)(
+  'cjs browser field false mapping does not warn when a property is accessed',
+  () => {
+    expect(
+      browserLogs.some((log) =>
+        log.includes(
+          'Cannot access "fs.__explicitBrowserFieldTest" in client code.',
+        ),
+      ),
+    ).toBe(false)
+  },
+)
+
 test('dep from linked dep (lodash-es)', async () => {
   await expect.poll(() => page.textContent('.deps-linked')).toBe('fooBarBaz')
 })
diff --git a/playground/optimize-deps/dep-cjs-browser-field-bare/internal.js b/playground/optimize-deps/dep-cjs-browser-field-bare/internal.js
index 8590297e4c5138..cffbba1e5c564f 100644
--- a/playground/optimize-deps/dep-cjs-browser-field-bare/internal.js
+++ b/playground/optimize-deps/dep-cjs-browser-field-bare/internal.js
@@ -2,5 +2,8 @@
 
 // eslint-disable-next-line n/prefer-node-protocol
 const events = require('events')
+// eslint-disable-next-line n/prefer-node-protocol
+const fs = require('fs')
 
-module.exports = 'foo' in events ? 'pong' : ''
+module.exports =
+  'foo' in events && fs.__explicitBrowserFieldTest === undefined ? 'pong' : ''
diff --git a/playground/optimize-deps/dep-cjs-browser-field-bare/package.json b/playground/optimize-deps/dep-cjs-browser-field-bare/package.json
index d78987e86ed2af..6810037c254b5b 100644
--- a/playground/optimize-deps/dep-cjs-browser-field-bare/package.json
+++ b/playground/optimize-deps/dep-cjs-browser-field-bare/package.json
@@ -4,6 +4,7 @@
   "version": "0.0.0",
   "main": "index.js",
   "browser": {
-    "events": "./events-shim.js"
+    "events": "./events-shim.js",
+    "fs": false
   }
 }