fix(changelog): include the root commit when --latest is used with one tag

.github/fixtures/test-latest-with-one-tag/commit.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 set -e
 
-GIT_COMMITTER_DATE="2021-01-23 01:23:45" git commit --allow-empty -m "Initial commit"
+GIT_COMMITTER_DATE="2021-01-23 01:23:45" git commit --allow-empty -m "feat: initial commit"
 
 GIT_COMMITTER_DATE="2021-01-23 01:23:46" git commit --allow-empty -m "feat: add feature 1"
 git tag v0.1.0

.github/fixtures/test-latest-with-one-tag/expected.md

@@ -6,6 +6,7 @@ All notable changes to this project will be documented in this file.
 
 ### Feat
 
+- Initial commit
 - Add feature 1
 
 <!-- generated by git-cliff -->

git-cliff-core/src/repo.rs

@@ -72,13 +72,21 @@ impl Repository {
 	pub fn commits(
 		&self,
 		range: Option<&str>,
+		include_root: bool,
 		include_path: Option<Vec<Pattern>>,
 		exclude_path: Option<Vec<Pattern>>,
 	) -> Result<Vec<Commit>> {
 		let mut revwalk = self.inner.revwalk()?;
 		revwalk.set_sorting(Sort::TOPOLOGICAL)?;
 		if let Some(range) = range {
-			revwalk.push_range(range)?;
+			// Push only the last range commit if we need to start at root.
+			if include_root {
+				if let Some(dots_index) = range.find("..") {
+					revwalk.push(Oid::from_str(&range[dots_index + 2..])?)?;
+				}
+			} else {
+				revwalk.push_range(range)?;
+			}
 		} else {
 			revwalk.push_head()?;
 		}
@@ -464,6 +472,18 @@ mod test {
 		.to_string())
 	}
 
+	fn get_root_commit_hash() -> Result<String> {
+		Ok(str::from_utf8(
+			Command::new("git")
+				.args(["rev-list", "--max-parents=0", "HEAD"])
+				.output()?
+				.stdout
+				.as_ref(),
+		)?
+		.trim_ascii_end()
+		.to_string())
+	}
+
 	fn get_last_tag() -> Result<String> {
 		Ok(str::from_utf8(
 			Command::new("git")
@@ -488,7 +508,7 @@ mod test {
 	#[test]
 	fn get_latest_commit() -> Result<()> {
 		let repository = get_repository()?;
-		let commits = repository.commits(None, None, None)?;
+		let commits = repository.commits(None, false, None, None)?;
 		let last_commit =
 			AppCommit::from(&commits.first().expect("no commits found").clone());
 		assert_eq!(get_last_commit_hash()?, last_commit.id);
@@ -586,6 +606,16 @@ mod test {
 		Ok(())
 	}
 
+	#[test]
+	fn includes_root_commit() -> Result<()> {
+		let repository = get_repository()?;
+		let commits = repository.commits(None, true, None, None)?;
+		let root_commit =
+			AppCommit::from(&commits.last().expect("no commits found").clone());
+		assert_eq!(get_root_commit_hash()?, root_commit.id);
+		Ok(())
+	}
+
 	fn create_temp_repo() -> (Repository, TempDir) {
 		let temp_dir =
 			TempDir::with_prefix("git-cliff-").expect("failed to create temp dir");

git-cliff/src/lib.rs

@@ -160,18 +160,20 @@ fn process_repository<'a>(
 
 	// Parse commits.
 	let mut commit_range = args.range.clone();
+	let mut include_root = false;
 	if args.unreleased {
 		if let Some(last_tag) = tags.last().map(|(k, _)| k) {
 			commit_range = Some(format!("{last_tag}..HEAD"));
 		}
 	} else if args.latest || args.current {
 		if tags.len() < 2 {
-			let commits = repository.commits(None, None, None)?;
+			let commits = repository.commits(None, false, None, None)?;
 			if let (Some(tag1), Some(tag2)) = (
 				commits.last().map(|c| c.id().to_string()),
 				tags.get_index(0).map(|(k, _)| k),
 			) {
 				commit_range = Some(format!("{tag1}..{tag2}"));
+				include_root = true;
 			}
 		} else {
 			let mut tag_index = tags.len() - 2;
@@ -208,6 +210,7 @@ fn process_repository<'a>(
 	}
 	let mut commits = repository.commits(
 		commit_range.as_deref(),
+		include_root,
 		args.include_path.clone(),
 		args.exclude_path.clone(),
 	)?;