ensure more specific default segments match parallel routes before …

…greedier catch-all segments

packages/next/src/build/index.ts

@@ -902,7 +902,9 @@ export default async function build(
                 validFileMatcher.isAppRouterPage(absolutePath) ||
                 // For now we only collect the root /not-found page in the app
                 // directory as the 404 fallback
-                validFileMatcher.isRootNotFound(absolutePath),
+                validFileMatcher.isRootNotFound(absolutePath) ||
+                // Default slots are also valid pages, and need to be considered during path normalization
+                validFileMatcher.isDefaultSlot(absolutePath),
               ignorePartFilter: (part) => part.startsWith('_'),
             })
           )

packages/next/src/build/normalize-catchall-routes.ts

@@ -1,3 +1,4 @@
+import { isDefaultRoute } from '../lib/is-default-route'
 import { isInterceptionRouteAppPath } from '../server/future/helpers/interception-routes'
 import { AppPathnameNormalizer } from '../server/future/normalizers/built/app/app-pathname-normalizer'
 
@@ -28,6 +29,7 @@ export function normalizeCatchAllRoutes(
   const filteredAppPaths = Object.keys(appPaths).filter(
     (route) => !isInterceptionRouteAppPath(route)
   )
+  const defaultPaths = new Set(filteredAppPaths.filter(isDefaultRoute))
 
   for (const appPath of filteredAppPaths) {
     for (const catchAllRoute of catchAllRoutes) {
@@ -41,7 +43,11 @@ export function normalizeCatchAllRoutes(
         // check if the appPath could match the catch-all
         appPath.startsWith(normalizedCatchAllRouteBasePath) &&
         // check if there's not already a slot value that could match the catch-all
-        !appPaths[appPath].some((path) => hasMatchedSlots(path, catchAllRoute))
+        !appPaths[appPath].some((path) =>
+          hasMatchedSlots(path, catchAllRoute)
+        ) &&
+        // check if there's not already a default route that would match in place of the catch-all
+        !hasMatchedDefault(appPath, defaultPaths)
       ) {
         appPaths[appPath].push(catchAllRoute)
       }
@@ -62,6 +68,26 @@ function hasMatchedSlots(path1: string, path2: string): boolean {
   return true
 }
 
+/**
+ * Checks if the given path would be matched by a default route.
+ * This is to avoid adding a catch-all route to a path that should be matched by a default route.
+ */
+function hasMatchedDefault(
+  pathToCheck: string,
+  defaultPaths: Set<string>
+): boolean {
+  const pathSegments = pathToCheck.split('/')
+
+  for (let i = 1; i <= pathSegments.length; i++) {
+    const partialRoute = pathSegments.slice(0, i).join('/')
+    if (defaultPaths.has(partialRoute + '/default')) {
+      return true
+    }
+  }
+
+  return false
+}
+
 const catchAllRouteRegex = /\[?\[\.\.\./
 
 function isCatchAllRoute(pathname: string): boolean {

packages/next/src/export/index.ts

@@ -55,6 +55,7 @@ import isError from '../lib/is-error'
 import { needsExperimentalReact } from '../lib/needs-experimental-react'
 import { formatManifest } from '../build/manifests/formatter/format-manifest'
 import { validateRevalidate } from '../server/lib/patch-fetch'
+import { isDefaultRoute } from '../lib/is-default-route'
 
 function divideSegments(number: number, segments: number): number[] {
   const result = []
@@ -302,7 +303,7 @@ export async function exportAppImpl(
 
   let hasApiRoutes = false
   for (const page of pages) {
-    // _document and _app are not real pages
+    // _document, _app, and default are not real pages
     // _error is exported as 404.html later on
     // API Routes are Node.js functions
 
@@ -311,7 +312,12 @@ export async function exportAppImpl(
       continue
     }
 
-    if (page === '/_document' || page === '/_app' || page === '/_error') {
+    if (
+      page === '/_document' ||
+      page === '/_app' ||
+      page === '/_error' ||
+      isDefaultRoute(page)
+    ) {
       continue
     }
 

packages/next/src/lib/is-default-route.ts

@@ -0,0 +1,3 @@
+export function isDefaultRoute(value?: string) {
+  return value?.endsWith('/default')
+}

packages/next/src/server/future/route-matcher-providers/dev/dev-app-page-route-matcher-provider.ts

@@ -19,9 +19,11 @@ export class DevAppPageRouteMatcherProvider extends FileCacheRouteMatcherProvide
 
     this.normalizers = new DevAppNormalizers(appDir, extensions)
 
-    // Match any page file that ends with `/page.${extension}` under the app
+    // Match any page file that ends with `/page.${extension}` or `/default.${extension}` under the app
     // directory.
-    this.expression = new RegExp(`[/\\\\]page\\.(?:${extensions.join('|')})$`)
+    this.expression = new RegExp(
+      `[/\\\\](page|default)\\.(?:${extensions.join('|')})$`
+    )
   }
 
   protected async transform(

packages/next/src/server/lib/find-page-file.ts

@@ -127,6 +127,10 @@ export function createValidFileMatcher(
     return validExtensionFileRegex.test(filePath) || isMetadataFile(filePath)
   }
 
+  function isDefaultSlot(filePath: string) {
+    return filePath.endsWith(`default.${pageExtensions[0]}`)
+  }
+
   function isRootNotFound(filePath: string) {
     if (!appDirPath) {
       return false
@@ -143,5 +147,6 @@ export function createValidFileMatcher(
     isAppRouterPage,
     isMetadataFile,
     isRootNotFound,
+    isDefaultSlot,
   }
 }

test/e2e/app-dir/parallel-routes-catchall-default/app/[locale]/[[...catchAll]]/page.tsx

@@ -0,0 +1,3 @@
+export default function Page() {
+  return <div>/[locale]/[[...catchAll]]/page.tsx</div>
+}

test/e2e/app-dir/parallel-routes-catchall-default/app/[locale]/nested/[foo]/[bar]/@slot/[baz]/page.tsx

@@ -0,0 +1,3 @@
+export default function Page({ params }) {
+  return <div>/[locale]/nested/[foo]/[bar]/@slot/[baz]/page.tsx</div>
+}

test/e2e/app-dir/parallel-routes-catchall-default/app/[locale]/nested/[foo]/[bar]/@slot/default.tsx

@@ -0,0 +1,3 @@
+export default function Page() {
+  return <div>/[locale]/nested/[foo]/[bar]/@slot/default.tsx</div>
+}

test/e2e/app-dir/parallel-routes-catchall-default/app/[locale]/nested/[foo]/[bar]/@slot/page.tsx

@@ -0,0 +1,3 @@
+export default function Foo() {
+  return <div>/[locale]/nested/[foo]/[bar]/@slot/page.tsx</div>
+}

test/e2e/app-dir/parallel-routes-catchall-default/app/[locale]/nested/[foo]/[bar]/default.tsx

@@ -0,0 +1,3 @@
+export default function Page() {
+  return <div>/[locale]/nested/[foo]/[bar]/default.tsx</div>
+}

test/e2e/app-dir/parallel-routes-catchall-default/app/[locale]/nested/[foo]/[bar]/layout.tsx

@@ -0,0 +1,8 @@
+export default function Layout({ children, slot }) {
+  return (
+    <>
+      Children: <div id="nested-children">{children}</div>
+      Slot: <div id="slot">{slot}</div>
+    </>
+  )
+}

test/e2e/app-dir/parallel-routes-catchall-default/app/layout.tsx

@@ -0,0 +1,11 @@
+import React from 'react'
+
+export default function Root({ children }: { children: React.ReactNode }) {
+  return (
+    <html>
+      <body>
+        Children: <div id="children">{children}</div>
+      </body>
+    </html>
+  )
+}

test/e2e/app-dir/parallel-routes-catchall-default/app/page.tsx

@@ -0,0 +1,5 @@
+import Link from 'next/link'
+
+export default async function Home() {
+  return <div>Root Page</div>
+}

test/e2e/app-dir/parallel-routes-catchall-default/next.config.js

@@ -0,0 +1,6 @@
+/**
+ * @type {import('next').NextConfig}
+ */
+const nextConfig = {}
+
+module.exports = nextConfig

test/e2e/app-dir/parallel-routes-catchall-default/parallel-routes-catchall-default.test.ts

@@ -0,0 +1,44 @@
+import { createNextDescribe } from 'e2e-utils'
+
+createNextDescribe(
+  'parallel-routes-catchall-default',
+  {
+    files: __dirname,
+  },
+  ({ next }) => {
+    it('should match default paths before catch-all', async () => {
+      let browser = await next.browser('/en/nested')
+
+      // we have a top-level catch-all but the /nested dir doesn't have a default/page until the /[foo]/[bar] segment
+      // so we expect the top-level catch-all to render
+      expect(await browser.elementById('children').text()).toBe(
+        '/[locale]/[[...catchAll]]/page.tsx'
+      )
+
+      browser = await next.browser('/en/nested/foo/bar')
+
+      // we're now at the /[foo]/[bar] segment, so we expect the matched page to be the default (since there's no page defined)
+      expect(await browser.elementById('nested-children').text()).toBe(
+        '/[locale]/nested/[foo]/[bar]/default.tsx'
+      )
+
+      // we expect the slot to match since there's a page defined at this segment
+      expect(await browser.elementById('slot').text()).toBe(
+        '/[locale]/nested/[foo]/[bar]/@slot/page.tsx'
+      )
+
+      browser = await next.browser('/en/nested/foo/bar/baz')
+
+      // the page slot should still be the one matched at the /[foo]/[bar] segment because it's the default and we
+      // didn't define a page at the /[foo]/[bar]/[baz] segment
+      expect(await browser.elementById('nested-children').text()).toBe(
+        '/[locale]/nested/[foo]/[bar]/default.tsx'
+      )
+
+      // however we do have a slot for the `[baz]` segment and so we expect that to no match
+      expect(await browser.elementById('slot').text()).toBe(
+        '/[locale]/nested/[foo]/[bar]/@slot/[baz]/page.tsx'
+      )
+    })
+  }
+)