Fix #44776 - Error on "Undo Last Commit" if executed against the initial commit

extensions/git/src/commands.ts

@@ -1123,7 +1123,12 @@ export class CommandCenter {
 		}
 
 		const commit = await repository.getCommit('HEAD');
-		await repository.reset('HEAD~');
+		if (commit.previousHashes.length > 0) {
+			await repository.reset('HEAD~');
+		} else {
+			await repository.deleteRef('HEAD');
+			await this.unstageAll(repository);
+		}
 		repository.inputBox.value = commit.message;
 	}
 

extensions/git/src/git.ts

@@ -481,6 +481,7 @@ export class Git {
 export interface Commit {
 	hash: string;
 	message: string;
+	previousHashes: string[];
 }
 
 export class GitStatusParser {
@@ -611,6 +612,16 @@ export function parseGitmodules(raw: string): Submodule[] {
 	return result;
 }
 
+export function parseGitCommit(raw: string): Commit | null {
+	const match = /^([0-9a-f]{40})\n(.*)\n([^]*)$/m.exec(raw.trim());
+	if (!match) {
+		return null;
+	}
+
+	const previousHashes = match[2] ? match[2].split(' ') : [];
+	return { hash: match[1], message: match[3], previousHashes };
+}
+
 export interface DiffOptions {
 	cached?: boolean;
 }
@@ -894,6 +905,11 @@ export class Repository {
 		await this.run(args);
 	}
 
+	async deleteRef(ref: string): Promise<void> {
+		const args = ['update-ref', '-d', ref];
+		await this.run(args);
+	}
+
 	async merge(ref: string): Promise<void> {
 		const args = ['merge', ref];
 
@@ -1287,14 +1303,8 @@ export class Repository {
 	}
 
 	async getCommit(ref: string): Promise<Commit> {
-		const result = await this.run(['show', '-s', '--format=%H\n%B', ref]);
-		const match = /^([0-9a-f]{40})\n([^]*)$/m.exec(result.stdout.trim());
-
-		if (!match) {
-			return Promise.reject<Commit>('bad commit format');
-		}
-
-		return { hash: match[1], message: match[2] };
+		const result = await this.run(['show', '-s', '--format=%H\n%P\n%B', ref]);
+		return parseGitCommit(result.stdout) || Promise.reject<Commit>('bad commit format');
 	}
 
 	async updateSubmodules(paths: string[]): Promise<void> {

extensions/git/src/repository.ts

@@ -292,6 +292,7 @@ export enum Operation {
 	GetCommitTemplate = 'GetCommitTemplate',
 	DeleteBranch = 'DeleteBranch',
 	RenameBranch = 'RenameBranch',
+	DeleteRef = 'DeleteRef',
 	Merge = 'Merge',
 	Ignore = 'Ignore',
 	Tag = 'Tag',
@@ -722,6 +723,10 @@ export class Repository implements Disposable {
 		await this.run(Operation.Reset, () => this.repository.reset(treeish, hard));
 	}
 
+	async deleteRef(ref: string): Promise<void> {
+		await this.run(Operation.DeleteRef, () => this.repository.deleteRef(ref));
+	}
+
 	@throttle
 	async fetch(): Promise<void> {
 		await this.run(Operation.Fetch, () => this.repository.fetch());

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

@@ -6,7 +6,7 @@
 'use strict';
 
 import 'mocha';
-import { GitStatusParser, parseGitmodules } from '../git';
+import { GitStatusParser, parseGitCommit, parseGitmodules } from '../git';
 import * as assert from 'assert';
 
 suite('git', () => {
@@ -175,4 +175,42 @@ suite('git', () => {
 			]);
 		});
 	});
+
+	suite('parseGitCommit', () => {
+		test('single previous commit', () => {
+			const GIT_OUTPUT_SINGLE_PARENT = `52c293a05038d865604c2284aa8698bd087915a1
+8e5a374372b8393906c7e380dbb09349c5385554
+This is a commit message.`;
+
+			assert.deepEqual(parseGitCommit(GIT_OUTPUT_SINGLE_PARENT), {
+				hash: '52c293a05038d865604c2284aa8698bd087915a1',
+				message: 'This is a commit message.',
+				previousHashes: ['8e5a374372b8393906c7e380dbb09349c5385554']
+			});
+		});
+
+		test('multiple previous commits', () => {
+			const GIT_OUTPUT_MULTIPLE_PARENTS = `52c293a05038d865604c2284aa8698bd087915a1
+8e5a374372b8393906c7e380dbb09349c5385554 df27d8c75b129ab9b178b386077da2822101b217
+This is a commit message.`;
+
+			assert.deepEqual(parseGitCommit(GIT_OUTPUT_MULTIPLE_PARENTS), {
+				hash: '52c293a05038d865604c2284aa8698bd087915a1',
+				message: 'This is a commit message.',
+				previousHashes: ['8e5a374372b8393906c7e380dbb09349c5385554', 'df27d8c75b129ab9b178b386077da2822101b217']
+			});
+		});
+
+		test('no previous commits', async () => {
+			const GIT_OUTPUT_NO_PARENTS = `52c293a05038d865604c2284aa8698bd087915a1
+
+This is a commit message.`;
+
+			assert.deepEqual(parseGitCommit(GIT_OUTPUT_NO_PARENTS), {
+				hash: '52c293a05038d865604c2284aa8698bd087915a1',
+				message: 'This is a commit message.',
+				previousHashes: []
+			});
+		});
+	});
 });