jacobwgillespie · jacobwgillespie · Mar 15, 2022 · Mar 15, 2022
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -12,7 +12,7 @@ jobs:
 
       - uses: actions/setup-go@v2
         with:
-          go-version: 1.16
+          go-version: 1.17
 
       - run: go mod tidy
       - run: go build
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
@@ -18,7 +18,7 @@ jobs:
 
       - uses: actions/setup-go@v2
         with:
-          go-version: 1.16
+          go-version: 1.17
 
       - uses: goreleaser/goreleaser-action@v2
         with:

diff --git a/git/git.go b/git/git.go
@@ -209,6 +209,40 @@ func SymbolicRef(ref string) (string, error) {
 	return firstLine(output), err
 }
 
+func TreeRef(ref string) (string, error) {
+	output, err := execGitQuiet("rev-parse", ref+"^{tree}")
+	if err != nil {
+		return "", err
+	}
+	return firstLine(output), err
+}
+
+func MergeBase(a, b string) (string, error) {
+	output, err := execGitQuiet("merge-base", a, b)
+	if err != nil {
+		return "", err
+	}
+	return firstLine(output), nil
+}
+
+func CommitTree(args ...string) (string, error) {
+	args = append([]string{"commit-tree"}, args...)
+	output, err := execGitQuiet(args...)
+	if err != nil {
+		return "", err
+	}
+	return firstLine(output), nil
+}
+
+func Cherry(args ...string) (string, error) {
+	args = append([]string{"cherry"}, args...)
+	output, err := execGitQuiet(args...)
+	if err != nil {
+		return "", err
+	}
+	return firstLine(output), nil
+}
+
 func execGit(args ...string) (string, error) {
 	cmd := exec.Command("git", args...)
 	cmd.Stderr = os.Stderr

diff --git a/go.mod b/go.mod
@@ -1,3 +1,3 @@
 module github.com/jacobwgillespie/git-sync
 
-go 1.16
+go 1.17
diff --git a/main.go b/main.go
@@ -81,7 +81,23 @@ func main() {
 			diff, err := git.NewRange(fullBranch, fullDefaultBranch)
 			check(err)
 
-			if diff.IsAncestor() {
+			// Determine if branch has been merged with a merge
+			shouldDelete := diff.IsAncestor()
+
+			// Otherwise, try to determine if branch has been squash-merged
+			if !shouldDelete {
+				ancestorHash, err := git.MergeBase(fullDefaultBranch, fullBranch)
+				check(err)
+				treeHash, err := git.TreeRef(fullBranch)
+				check(err)
+				danglingCommit, err := git.CommitTree(treeHash, "-p", ancestorHash, "-m", fmt.Sprintf("Dangling branch %s", branch))
+				check(err)
+				result, err := git.Cherry(fullDefaultBranch, danglingCommit)
+				check(err)
+				shouldDelete = strings.HasPrefix(result, "-")
+			}
+
+			if shouldDelete {
 				if branch == currentBranch {
 					git.Quiet("checkout", "--quiet", defaultBranch)
 					currentBranch = defaultBranch