parallel routes: fix catch all route support (vercel#58215)

This PR fixes a bug where parallel routes would not apply appropriately on navigation when used within slots.

The following scenarios:
```
/foo
   /bar
   /@slot
     /[...catchAll]
```

or 

```
/foo
  /[...catchAll]
  /@slot
     /bar
```

will now function correctly when accessing /foo/bar, and Next.js will render both /bar and the catchall slots.

The issue was that the tree constructed by `next-app-loader` for a given path, /foo/bar in the example, would not include the paths for the catch-all files at build time. The routing was done 1-1 when compiling files, where a path would only match one file, with parallel routes, a path could hit a defined path but also a catch all route at the same time in a different slot.

The fix consists of adding another normalisation layer that will look for all catch-all in `appPaths` and iterate over the other paths and add the relevant information when needed.

The tricky part was making sure that we only included the relevant paths to the loader: we don't want to overwrite a slot with a catch all if there's already a more specific subpath in that slot, i.e. if there's /foo/@slot/bar/page.js, no need to inject /foo/@slot/bar/[...catchAll]. 

One thing that is not supported right now is optional catch all routes, will add later.

fixes vercel#48719
fixes vercel#49662

packages/next/src/build/entries.ts

@@ -60,6 +60,7 @@ import {
 import { isStaticMetadataRouteFile } from '../lib/metadata/is-metadata-route'
 import { RouteKind } from '../server/future/route-kind'
 import { encodeToBase64 } from './webpack/loaders/utils'
+import { normalizeCatchAllRoutes } from './normalize-catchall-routes'
 
 export function sortByPageExts(pageExtensions: string[]) {
   return (a: string, b: string) => {
@@ -545,6 +546,9 @@ export async function createEntrypoints(
       )
     }
 
+    // TODO: find a better place to do this
+    normalizeCatchAllRoutes(appPathsPerRoute)
+
     // Make sure to sort parallel routes to make the result deterministic.
     appPathsPerRoute = Object.fromEntries(
       Object.entries(appPathsPerRoute).map(([k, v]) => [k, v.sort()])

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

@@ -0,0 +1,53 @@
+import { AppPathnameNormalizer } from '../server/future/normalizers/built/app/app-pathname-normalizer'
+
+/**
+ * This function will transform the appPaths in order to support catch-all routes and parallel routes.
+ * It will traverse the appPaths, looking for catch-all routes and try to find parallel routes that could match
+ * the catch-all. If it finds a match, it will add the catch-all to the parallel route's list of possible routes.
+ *
+ * @param appPaths  The appPaths to transform
+ */
+export function normalizeCatchAllRoutes(
+  appPaths: Record<string, string[]>,
+  normalizer = new AppPathnameNormalizer()
+) {
+  const catchAllRoutes = [
+    ...new Set(Object.values(appPaths).flat().filter(isCatchAllRoute)),
+  ]
+
+  for (const appPath of Object.keys(appPaths)) {
+    for (const catchAllRoute of catchAllRoutes) {
+      const normalizedCatchAllRoute = normalizer.normalize(catchAllRoute)
+      const normalizedCatchAllRouteBasePath = normalizedCatchAllRoute.slice(
+        0,
+        normalizedCatchAllRoute.indexOf('[')
+      )
+
+      if (
+        // first check if the appPath could match the catch-all
+        appPath.startsWith(normalizedCatchAllRouteBasePath) &&
+        // then check if there's not already a slot value that could match the catch-all
+        !appPaths[appPath].some((path) => hasMatchedSlots(path, catchAllRoute))
+      ) {
+        appPaths[appPath].push(catchAllRoute)
+      }
+    }
+  }
+}
+
+function hasMatchedSlots(path1: string, path2: string): boolean {
+  const slots1 = path1.split('/').filter((segment) => segment.startsWith('@'))
+  const slots2 = path2.split('/').filter((segment) => segment.startsWith('@'))
+
+  if (slots1.length !== slots2.length) return false
+
+  for (let i = 0; i < slots1.length; i++) {
+    if (slots1[i] !== slots2[i]) return false
+  }
+
+  return true
+}
+
+function isCatchAllRoute(pathname: string): boolean {
+  return pathname.includes('[...') || pathname.includes('[[...')
+}

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

@@ -4,6 +4,7 @@ import { RouteKind } from '../../route-kind'
 import { FileCacheRouteMatcherProvider } from './file-cache-route-matcher-provider'
 
 import { DevAppNormalizers } from '../../normalizers/built/app'
+import { normalizeCatchAllRoutes } from '../../../../build/normalize-catchall-routes'
 
 export class DevAppPageRouteMatcherProvider extends FileCacheRouteMatcherProvider<AppPageRouteMatcher> {
   private readonly expression: RegExp
@@ -56,6 +57,8 @@ export class DevAppPageRouteMatcherProvider extends FileCacheRouteMatcherProvide
       else appPaths[pathname] = [page]
     }
 
+    normalizeCatchAllRoutes(appPaths)
+
     const matchers: Array<AppPageRouteMatcher> = []
     for (const filename of routeFilenames) {
       // Grab the cached values (and the appPaths).

test/e2e/app-dir/parallel-routes-and-interception/app/parallel-catchall/@slot/baz/page.tsx

@@ -0,0 +1,3 @@
+export default function Baz() {
+  return 'baz slot'
+}

test/e2e/app-dir/parallel-routes-and-interception/app/parallel-catchall/bar/page.tsx

@@ -0,0 +1,3 @@
+export default function Foo() {
+  return 'bar slot'
+}

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

@@ -16,6 +16,9 @@ export default function Layout({ children, slot }) {
       <div>
         <Link href="/parallel-catchall/bar">catchall bar</Link>
       </div>
+      <div>
+        <Link href="/parallel-catchall/baz">catchall baz</Link>
+      </div>
     </div>
   )
 }

test/e2e/app-dir/parallel-routes-and-interception/parallel-routes-and-interception.test.ts

@@ -314,7 +314,7 @@ createNextDescribe(
         await browser.elementByCss('[href="/parallel-catchall/bar"]').click()
         await check(
           () => browser.waitForElementByCss('#main').text(),
-          'main catchall'
+          'bar slot'
         )
         await check(
           () => browser.waitForElementByCss('#slot-content').text(),
@@ -328,14 +328,14 @@ createNextDescribe(
           'foo slot'
         )
 
-        await browser.elementByCss('[href="/parallel-catchall/bar"]').click()
+        await browser.elementByCss('[href="/parallel-catchall/baz"]').click()
         await check(
           () => browser.waitForElementByCss('#main').text(),
           'main catchall'
         )
         await check(
           () => browser.waitForElementByCss('#slot-content').text(),
-          'slot catchall'
+          'baz slot'
         )
       })