Fix: fix pages in Route Groups returning 500 with output: "standalone" (#43746)

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Fixes [#43367
(comment)](https://github.com/vercel/next.js/issues/43367#issuecomment-1338617317)

This fixes the issue in which pages that are in Route Groups return
status code 500 when built with `output: "standalone"` because of the
lack of required chunks in `.next/standalone/.next/server/chunks` by
handling their `.nft.json` files properly through using their
denormalized page paths, rather than their normalized ones to resolve
those files in `copyTracedFiles`.

## Bug

- [x] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [ ]
[e2e](https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs)
tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm build && pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)

packages/next/build/index.ts

@@ -536,6 +536,7 @@ export default async function build(
         )
 
       let mappedAppPages: { [page: string]: string } | undefined
+      let denormalizedAppPages: string[] | undefined
 
       if (appPaths && appDir) {
         mappedAppPages = nextBuildSpan
@@ -586,7 +587,8 @@ export default async function build(
       const conflictingAppPagePaths: [pagePath: string, appPath: string][] = []
       const appPageKeys: string[] = []
       if (mappedAppPages) {
-        for (const appKey in mappedAppPages) {
+        denormalizedAppPages = Object.keys(mappedAppPages)
+        for (const appKey of denormalizedAppPages) {
           const normalizedAppPageKey = normalizeAppPath(appKey) || '/'
           const pagePath = mappedPages[normalizedAppPageKey]
           if (pagePath) {
@@ -596,7 +598,6 @@ export default async function build(
               appPath.replace(/^private-next-app-dir/, 'app'),
             ])
           }
-
           appPageKeys.push(normalizedAppPageKey)
         }
       }
@@ -2068,7 +2069,7 @@ export default async function build(
               dir,
               distDir,
               pageKeys.pages,
-              pageKeys.app,
+              denormalizedAppPages,
               outputFileTracingRoot,
               requiredServerFiles.config,
               middlewareManifest

packages/next/build/utils.ts

@@ -1597,7 +1597,7 @@ export function detectConflictingPaths(
 export async function copyTracedFiles(
   dir: string,
   distDir: string,
-  pageKeys: ReadonlyArray<string>,
+  pageKeys: readonly string[],
   appPageKeys: readonly string[] | undefined,
   tracingRoot: string,
   serverConfig: { [key: string]: any },
@@ -1712,7 +1712,7 @@ export async function copyTracedFiles(
       if (middlewareManifest.functions.hasOwnProperty(page)) {
         continue
       }
-      const pageFile = path.join(distDir, 'server', 'app', `${page}`, 'page.js')
+      const pageFile = path.join(distDir, 'server', 'app', `${page}.js`)
       const pageTraceFile = `${pageFile}.nft.json`
       await handleTraceFiles(pageTraceFile).catch((err) => {
         Log.warn(`Failed to copy traced files for ${pageFile}`, err)

test/e2e/app-dir/standalone.test.ts

@@ -40,10 +40,39 @@ describe('output: standalone with app dir', () => {
     await next.destroy()
   })
 
+  if ((global as any).isNextStart) {
+    it('should handle trace files correctly for route groups (nodejs only)', async () => {
+      expect(next.cliOutput).not.toContain('Failed to copy traced files')
+      const serverDirPath = path.join(
+        next.testDir,
+        '.next/standalone/.next/server'
+      )
+      for (const page of [
+        '(newroot)/dashboard/another',
+        '(newroot)/dashboard/project/[projectId]',
+        '(rootonly)/dashboard/changelog',
+      ]) {
+        const pagePath = path.join(serverDirPath, 'app', page)
+
+        expect(
+          await fs.pathExists(path.join(pagePath, 'page.js.nft.json'))
+        ).toBe(true)
+
+        const files = (
+          await fs.readJSON(path.join(pagePath, 'page.js.nft.json'))
+        ).files as string[]
+
+        for (const file of files) {
+          expect(await fs.pathExists(path.join(pagePath, file))).toBe(true)
+        }
+      }
+    })
+  }
+
   it('should work correctly with output standalone', async () => {
     const tmpFolder = path.join(os.tmpdir(), 'next-standalone-' + Date.now())
     await fs.move(path.join(next.testDir, '.next/standalone'), tmpFolder)
-    let server
+    let server: any
 
     try {
       const testServer = path.join(tmpFolder, 'server.js')
@@ -66,7 +95,12 @@ describe('output: standalone with app dir', () => {
         '/api/hello',
         '/blog/first',
         '/dashboard',
+        '/dashboard/another',
+        '/dashboard/changelog',
+        '/dashboard/deployments/breakdown',
         '/dashboard/deployments/123',
+        '/dashboard/hello',
+        '/dashboard/project/123',
         '/catch-all/first',
       ]) {
         const res = await fetchViaHTTP(appPort, testPath)