fix(ssr): mark builtin modules as side effect free (#15658)

packages/vite/src/node/plugins/resolve.ts

@@ -407,7 +407,9 @@ export function resolvePlugin(resolveOptions: InternalResolveOptions): Plugin {
               this.error(message)
             }
 
-            return options.idOnly ? id : { id, external: true }
+            return options.idOnly
+              ? id
+              : { id, external: true, moduleSideEffects: false }
           } else {
             if (!asSrc) {
               debug?.(

playground/ssr-resolve/__tests__/ssr-resolve.spec.ts

@@ -25,3 +25,11 @@ test.runIf(isBuild)('correctly resolve entrypoints', async () => {
 
   await expect(import(`${testDir}/dist/main.mjs`)).resolves.toBeTruthy()
 })
+
+test.runIf(isBuild)(
+  'node builtins should not be bundled if not used',
+  async () => {
+    const contents = readFile('dist/main.mjs')
+    expect(contents).not.include(`node:url`)
+  },
+)

playground/ssr-resolve/main.js

@@ -6,6 +6,7 @@ import fileEntry from '@vitejs/test-entries/file'
 import pkgExportsEntry from '@vitejs/test-resolve-pkg-exports/entry'
 import deepFoo from '@vitejs/test-deep-import/foo'
 import deepBar from '@vitejs/test-deep-import/bar'
+import { used } from './util'
 
 export default `
   entries/dir: ${dirEntry}
@@ -13,4 +14,5 @@ export default `
   pkg-exports/entry: ${pkgExportsEntry}
   deep-import/foo: ${deepFoo}
   deep-import/bar: ${deepBar}
+  util: ${used(['[success]'])}
 `

playground/ssr-resolve/util.js

@@ -0,0 +1,10 @@
+import { pathToFileURL } from 'node:url'
+
+export function used(s) {
+  return s
+}
+
+// This is not used, so `node:url` should not be bundled
+export function treeshaken(s) {
+  return pathToFileURL(s)
+}