Turbopack build: Add marker for when a build used Turbopack

timneutkens · timneutkens · commit 90eb5a7a46a0 · 2025-04-01T12:05:46.000+02:00
diff --git a/packages/next/src/build/index.ts b/packages/next/src/build/index.ts
@@ -1452,6 +1452,7 @@ export default async function build(
       let shutdownPromise = Promise.resolve()
       if (!isGenerateMode) {
         if (turboNextBuild) {
+          await writeFileUtf8(path.join(distDir, 'IS_TURBOPACK_BUILD'), '')
           const {
             duration: compilerDuration,
             shutdownPromise: p,
diff --git a/test/production/app-dir/turbopack-build-marker/app/layout.tsx b/test/production/app-dir/turbopack-build-marker/app/layout.tsx
@@ -0,0 +1,8 @@
+import { ReactNode } from 'react'
+export default function Root({ children }: { children: ReactNode }) {
+  return (
+    <html>
+      <body>{children}</body>
+    </html>
+  )
+}
diff --git a/test/production/app-dir/turbopack-build-marker/app/page.tsx b/test/production/app-dir/turbopack-build-marker/app/page.tsx
@@ -0,0 +1,3 @@
+export default function Page() {
+  return <p>hello world</p>
+}
diff --git a/test/production/app-dir/turbopack-build-marker/next.config.js b/test/production/app-dir/turbopack-build-marker/next.config.js
@@ -0,0 +1,6 @@
+/**
+ * @type {import('next').NextConfig}
+ */
+const nextConfig = {}
+
+module.exports = nextConfig
diff --git a/test/production/app-dir/turbopack-build-marker/turbopack-build-marker.test.ts b/test/production/app-dir/turbopack-build-marker/turbopack-build-marker.test.ts
@@ -0,0 +1,13 @@
+import { nextTestSetup } from 'e2e-utils'
+;(process.env.TURBOPACK ? describe : describe.skip)(
+  'turbopack-build-marker',
+  () => {
+    const { next } = nextTestSetup({
+      files: __dirname,
+    })
+
+    it('should have Turbopack build marker', async () => {
+      expect(await next.hasFile('.next/IS_TURBOPACK_BUILD')).toBe(true)
+    })
+  }
+)

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+export default function Page() {`
	`2`	`+ return <p>hello world</p>`
	`3`	`+}`