fix(core): asset hash is different between linux and windows

packages/@aws-cdk/core/lib/fs/fingerprint.ts

@@ -53,24 +53,26 @@ export function fingerprint(fileOrDirectory: string, options: FingerprintOptions
   return hash.digest('hex');
 
   function _processFileOrDirectory(symbolicPath: string, isRootDir: boolean = false, realPath = symbolicPath) {
-    const relativePath = path.relative(fileOrDirectory, symbolicPath);
-
     if (!isRootDir && ignoreStrategy.ignores(symbolicPath)) {
       return;
     }
 
     const stat = fs.lstatSync(realPath);
 
+    // Use relative path as hash component. Normalize it with forward slashes to ensure
+    // same hash on Windows and Linux.
+    const hashComponent = path.relative(fileOrDirectory, symbolicPath).replace(/\\/g, '/');
+
     if (stat.isSymbolicLink()) {
       const linkTarget = fs.readlinkSync(realPath);
       const resolvedLinkTarget = path.resolve(path.dirname(realPath), linkTarget);
       if (shouldFollow(follow, rootDirectory, resolvedLinkTarget)) {
         _processFileOrDirectory(symbolicPath, false, resolvedLinkTarget);
       } else {
-        _hashField(hash, `link:${relativePath}`, linkTarget);
+        _hashField(hash, `link:${hashComponent}`, linkTarget);
       }
     } else if (stat.isFile()) {
-      _hashField(hash, `file:${relativePath}`, contentFingerprint(realPath));
+      _hashField(hash, `file:${hashComponent}`, contentFingerprint(realPath));
     } else if (stat.isDirectory()) {
       for (const item of fs.readdirSync(realPath).sort()) {
         _processFileOrDirectory(path.join(symbolicPath, item), false, path.join(realPath, item));

packages/@aws-cdk/core/test/fs/fs-fingerprint.test.ts

@@ -178,4 +178,22 @@ describe('fs fingerprint', () => {
 
     });
   });
+
+  test('normalizes relative path', () => {
+    // Simulate a Windows path.relative()
+    const originalPathRelative = path.relative;
+    const pathRelativeSpy = jest.spyOn(path, 'relative').mockImplementation((from: string, to: string): string => {
+      return originalPathRelative(from, to).replace(/\//g, '\\');
+    });
+
+    const hash1 = FileSystem.fingerprint(path.join(__dirname, 'fixtures', 'test1'));
+
+    // Restore Linux behavior
+    pathRelativeSpy.mockRestore();
+
+    const hash2 = FileSystem.fingerprint(path.join(__dirname, 'fixtures', 'test1'));
+
+    // Relative paths are normalized
+    expect(hash1).toEqual(hash2);
+  });
 });