feat(cli): commit hash validation

Fixes conventional-changelog#3376

Author: Mersho

@commitlint/cli/src/cli.ts

@@ -213,11 +213,26 @@ async function main(args: MainArgs): Promise<void> {
 		throw err;
 	}
 
+	if (
+		typeof flags.from !== 'undefined' &&
+		typeof flags.to !== 'undefined' &&
+		flags.from === flags.to
+	) {
+		const err = new CliError(
+			'Please use a different commit hash for --from and --to, not the same. (Or use the --last flag for analyzing just the last commit.)',
+			pkg.name
+		);
+		yargs.showHelp('log');
+		console.log(err.message);
+		throw err;
+	}
+
 	const input = await (fromStdin
 		? stdin()
 		: read({
 				to: flags.to,
 				from: flags.from,
+				last: flags.last,
 				edit: flags.edit,
 				cwd: flags.cwd,
 				gitLogArgs: flags['git-log-args'],

@commitlint/read/src/read.ts

@@ -7,6 +7,7 @@ interface GetCommitMessageOptions {
 	cwd?: string;
 	from?: string;
 	to?: string;
+	last?: boolean;
 	edit?: boolean | string;
 	gitLogArgs?: string;
 }
@@ -15,13 +16,16 @@ interface GetCommitMessageOptions {
 export default async function getCommitMessages(
 	settings: GetCommitMessageOptions
 ): Promise<string[]> {
-	const {cwd, from, to, edit, gitLogArgs} = settings;
+	const {cwd, from, to, last, edit, gitLogArgs} = settings;
 
 	if (edit) {
 		return getEditCommit(cwd, edit);
 	}
 
 	let gitOptions: GitOptions = {from, to};
+	if (last) {
+		gitOptions = {from: 'HEAD~1', to: 'HEAD'};
+	}
 	if (gitLogArgs) {
 		gitOptions = {
 			...minimist(gitLogArgs.split(' ')),