From 22b16e1e37f253236c8508bb68280b2ce2c5ca37 Mon Sep 17 00:00:00 2001
From: JJ Kasper <jj@jjsweb.site>
Date: Thu, 17 Nov 2022 17:30:01 -0800
Subject: [PATCH] Ensure backslash is correctly handled in find-page-file
 (#43057)

## Bug

- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Errors have a helpful link attached, see `contributing.md`

Fixes:
https://github.com/vercel/next.js/issues/43019#issuecomment-1319340037
---
 packages/next/server/lib/find-page-file.ts | 2 +-
 test/unit/find-page-file.test.ts           | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/next/server/lib/find-page-file.ts b/packages/next/server/lib/find-page-file.ts
index bba2122f002c11b..c59915de21f9529 100644
--- a/packages/next/server/lib/find-page-file.ts
+++ b/packages/next/server/lib/find-page-file.ts
@@ -67,6 +67,6 @@ export async function findPageFile(
 // The filename should start with 'page' and end with one of the allowed extensions
 export function isLayoutsLeafPage(filePath: string, pageExtensions: string[]) {
   return new RegExp(
-    `(^page|[\\/]page)\\.(?:${pageExtensions.join('|')})$`
+    `(^page|[\\\\/]page)\\.(?:${pageExtensions.join('|')})$`
   ).test(filePath)
 }
diff --git a/test/unit/find-page-file.test.ts b/test/unit/find-page-file.test.ts
index d49fb4347bd978d..e4972669e494773 100644
--- a/test/unit/find-page-file.test.ts
+++ b/test/unit/find-page-file.test.ts
@@ -53,6 +53,9 @@ describe('isLayoutsLeafPage', () => {
     expect(isLayoutsLeafPage('./page.jsx', pageExtensions)).toBe(true)
     expect(isLayoutsLeafPage('/page.ts', pageExtensions)).toBe(true)
     expect(isLayoutsLeafPage('/path/page.tsx', pageExtensions)).toBe(true)
+    expect(isLayoutsLeafPage('\\path\\page.tsx', pageExtensions)).toBe(true)
+    expect(isLayoutsLeafPage('.\\page.jsx', pageExtensions)).toBe(true)
+    expect(isLayoutsLeafPage('\\page.js', pageExtensions)).toBe(true)
   })
 
   it('should determine other files under layout routes as non leaf node', () => {