git: Fix discarding untracked files on Windows subst drives

extensions/git/src/repository.ts

@@ -1473,14 +1473,25 @@ export class Repository implements Disposable {
 				if (toClean.length > 0) {
 					if (discardUntrackedChangesToTrash) {
 						try {
+							// Helper function to get the real path for subst drives
+							const getRealPath = (fsPath: string) => {
+								return this.rootRealPath && fsPath.startsWith(this.root)
+									? path.join(this.rootRealPath, fsPath.substring(this.root.length))
+									: fsPath;
+							};
+
 							// Attempt to move the first resource to the recycle bin/trash to check
 							// if it is supported. If it fails, we show a confirmation dialog and
 							// fall back to deletion.
-							await workspace.fs.delete(Uri.file(toClean[0]), { useTrash: true });
+							const firstFileRealPath = getRealPath(toClean[0]);
+							await workspace.fs.delete(Uri.file(firstFileRealPath), { useTrash: true });
 
 							const limiter = new Limiter<void>(5);
 							await Promise.all(toClean.slice(1).map(fsPath => limiter.queue(
-								async () => await workspace.fs.delete(Uri.file(fsPath), { useTrash: true }))));
+								async () => {
+									const realPath = getRealPath(fsPath);
+									await workspace.fs.delete(Uri.file(realPath), { useTrash: true });
+								})));
 						} catch {
 							const message = isWindows
 								? l10n.t('Failed to delete using the Recycle Bin. Do you want to permanently delete instead?')

extensions/git/src/test/repository.test.ts

@@ -0,0 +1,61 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import 'mocha';
+import assert from 'assert';
+import path from 'path';
+import { isWindows } from '../util';
+
+suite('Repository path handling', () => {
+	// Skip all tests if not on Windows, as these tests are for Windows-specific path handling
+	suiteSetup(function () {
+		if (!isWindows) {
+			this.skip();
+		}
+	});
+
+	// Test the path manipulation logic directly for subst drives
+	test('subst drive path correction', () => {
+		const root = 'X:\\repo';
+		const rootRealPath = 'C:\\real\\path\\repo';
+		const fsPath = 'X:\\repo\\file.txt';
+
+		// This is the logic from the fix we implemented
+		const realPath = fsPath.startsWith(root)
+			? path.join(rootRealPath, fsPath.substring(root.length))
+			: fsPath;
+
+		// Verify the path is correctly transformed
+		assert.strictEqual(realPath, 'C:\\real\\path\\repo\\file.txt');
+	});
+
+	test('non-subst path should remain unchanged', () => {
+		const root = 'C:\\repo';
+		const rootRealPath = 'C:\\repo';
+		const fsPath = 'C:\\repo\\file.txt';
+
+		// Same logic as implemented in the fix
+		const realPath = fsPath.startsWith(root)
+			? path.join(rootRealPath, fsPath.substring(root.length))
+			: fsPath;
+
+		// Path should remain unchanged
+		assert.strictEqual(realPath, 'C:\\repo\\file.txt');
+	});
+
+	test('path outside repository should remain unchanged', () => {
+		const root = 'X:\\repo';
+		const rootRealPath = 'C:\\real\\path\\repo';
+		const fsPath = 'D:\\other\\file.txt';
+
+		// Same logic as implemented in the fix
+		const realPath = fsPath.startsWith(root)
+			? path.join(rootRealPath, fsPath.substring(root.length))
+			: fsPath;
+
+		// Path should remain unchanged
+		assert.strictEqual(realPath, 'D:\\other\\file.txt');
+	});
+});