Guard export fallback variant paths

feedthejim · feedthejim · commit d8369461a414 · 2026-04-20T13:53:54.000-07:00
diff --git a/packages/next/src/export/index.ts b/packages/next/src/export/index.ts
@@ -1186,7 +1186,7 @@ async function exportAppImpl(
 
           await Promise.all(
             manifestEntries.map(({ fallbackPath, orig }) =>
-              emitFallbackArtifacts(fallbackPath, orig, false)
+              emitFallbackArtifacts(fallbackPath, orig, true)
             )
           )
         }
diff --git a/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/docs/[...slug]/page.js b/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/docs/[...slug]/page.js
@@ -0,0 +1,12 @@
+import { Suspense } from 'react'
+import DocsCatchAllClient from './slug-client'
+
+export default function DocsCatchAllPage() {
+  return (
+    <main>
+      <Suspense fallback={<h1>Loading docs catch-all...</h1>}>
+        <DocsCatchAllClient />
+      </Suspense>
+    </main>
+  )
+}
diff --git a/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/docs/[...slug]/slug-client.js b/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/docs/[...slug]/slug-client.js
@@ -0,0 +1,8 @@
+'use client'
+
+import { useParams } from 'next/navigation'
+
+export default function DocsCatchAllClient() {
+  const { slug } = useParams()
+  return <h1>{`catchall:${slug.join('/')}`}</h1>
+}
diff --git a/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/docs/[section]/[page]/page.js b/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/docs/[section]/[page]/page.js
@@ -0,0 +1,16 @@
+import { Suspense } from 'react'
+import DocsSectionPageClient from './params-client'
+
+export function generateStaticParams() {
+  return [{ section: 'api', page: 'reference' }]
+}
+
+export default function DocsSectionPage() {
+  return (
+    <main>
+      <Suspense fallback={<h1>Loading docs section page...</h1>}>
+        <DocsSectionPageClient />
+      </Suspense>
+    </main>
+  )
+}
diff --git a/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/docs/[section]/[page]/params-client.js b/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/docs/[section]/[page]/params-client.js
@@ -0,0 +1,8 @@
+'use client'
+
+import { useParams } from 'next/navigation'
+
+export default function DocsSectionPageClient() {
+  const { section, page } = useParams()
+  return <h1>{`${section}:${page}`}</h1>
+}
diff --git a/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/docs/page.js b/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/docs/page.js
@@ -0,0 +1,3 @@
+export default function DocsPage() {
+  return <p>docs</p>
+}
diff --git a/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/layout.js b/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/layout.js
@@ -0,0 +1,7 @@
+export default function RootLayout({ children }) {
+  return (
+    <html>
+      <body>{children}</body>
+    </html>
+  )
+}
diff --git a/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/page.js b/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/app/page.js
@@ -0,0 +1,3 @@
+export default function Page() {
+  return <p>home</p>
+}
diff --git a/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/next.config.js b/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/next.config.js
@@ -0,0 +1,9 @@
+/**
+ * @type {import('next').NextConfig}
+ */
+const nextConfig = {
+  output: 'export',
+  cacheComponents: true,
+}
+
+module.exports = nextConfig
diff --git a/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/public/docs/__fallback/__route_0.html b/test/e2e/app-dir-export/fixtures/dynamic-fallback-internal-path-conflict/public/docs/__fallback/__route_0.html
@@ -0,0 +1 @@
+reserved fallback variant path
diff --git a/test/e2e/app-dir-export/test/dynamic-fallback-conflict.test.ts b/test/e2e/app-dir-export/test/dynamic-fallback-conflict.test.ts
@@ -116,3 +116,31 @@ describe('app dir - output export fallback conflicts', () => {
     }
   })
 })
+
+describe('app dir - output export fallback internal path collisions', () => {
+  const { next, skipped } = nextTestSetup({
+    files: join(
+      __dirname,
+      '..',
+      'fixtures',
+      'dynamic-fallback-internal-path-conflict'
+    ),
+    skipStart: true,
+    skipDeployment: true,
+    disableAutoSkewProtection: true,
+  })
+
+  if (skipped) {
+    return
+  }
+
+  it('errors when a multi-route fallback artifact path is already occupied', async () => {
+    const { exitCode, cliOutput } = await next.build()
+
+    expect(exitCode).toBe(1)
+    expect(cliOutput).toContain(
+      'conflicts with the internal "__fallback" path used by dynamic route fallbacks in static export mode'
+    )
+    expect(cliOutput).toContain('/docs/__fallback/__route_0')
+  })
+})

Original file line number	Diff line number	Diff line change
`@@ -1186,7 +1186,7 @@ async function exportAppImpl(`
`1186`	`1186`
`1187`	`1187`	`await Promise.all(`
`1188`	`1188`	`manifestEntries.map(({ fallbackPath, orig }) =>`
`1189`		`- emitFallbackArtifacts(fallbackPath, orig, false)`
	`1189`	`+ emitFallbackArtifacts(fallbackPath, orig, true)`
`1190`	`1190`	`)`
`1191`	`1191`	`)`
`1192`	`1192`	`}`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+export default function DocsPage() {`
	`2`	`+ return <p>docs</p>`
	`3`	`+}`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+export default function Page() {`
	`2`	`+ return <p>home</p>`
	`3`	`+}`