Add land-pr command

bin/git-landpr

@@ -0,0 +1,123 @@
+#!/usr/bin/env python3
+
+import argparse
+import collections
+import json
+import subprocess
+
+
+class _GitError(Exception):
+    pass
+
+
+def _build_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("commit", help="The commit to land")
+    return parser
+
+
+def _run_git_command(args: list[str]) -> str:
+    try:
+        output: bytes = subprocess.check_output(["git"] + args)
+        return output.strip().decode("utf-8")
+    except subprocess.CalledProcessError:
+        raise _GitError()
+    except UnicodeDecodeError:
+        print(f"error: output was {output}")
+        raise
+
+
+def _get_possible_shas() -> list[str]:
+    return _run_git_command(
+        ["log", "--no-show-signature", "--pretty=%H", "@{upstream}..HEAD"]
+    ).splitlines()
+
+
+def _get_branch_name(commit: str) -> str:
+    return _run_git_command(["pilebranchname", commit])
+
+
+def _get_pr_url(commit: str) -> str:
+    """Get the PR URL for a commit by finding the PR with a matching head branch."""
+    branch_name = _get_branch_name(commit)
+    result = subprocess.run(
+        ["gh", "pr", "list", "--head", branch_name, "--json", "url", "--limit", "1"],
+        capture_output=True,
+        text=True,
+    )
+    if result.returncode != 0:
+        raise SystemExit(
+            f"error: failed to find PR for branch {branch_name}, {result.stderr.strip()}"
+        )
+
+    prs = json.loads(result.stdout)
+    if not prs:
+        raise SystemExit(f"error: no PR found for branch {branch_name}")
+
+    return prs[0]["url"]
+
+
+def _get_prs_targeting_base(base_branch: str) -> list[str]:
+    """Get all PR head branches that target the given base branch."""
+    output = subprocess.check_output(
+        ["gh", "pr", "list", "--base", base_branch, "--json", "headRefName"],
+    )
+    prs = json.loads(output)
+    return [pr["headRefName"] for pr in prs]
+
+
+def _find_commit_for_branch(branch_name: str, possible_shas: list[str]) -> str | None:
+    """Find the local commit that corresponds to a branch name."""
+    for sha in possible_shas:
+        if _get_branch_name(sha) == branch_name:
+            return sha
+    return None
+
+
+def _main(commit: str) -> None:
+    # Normalize HEAD -> commit, etc
+    commit = _run_git_command(["rev-parse", commit])
+
+    pr_url = _get_pr_url(commit)
+    branch_being_merged = _get_branch_name(commit)
+
+    subprocess.check_call(["gh", "pr", "merge", pr_url, "--squash"])
+    try:
+        _run_git_command(["pull"])
+    except _GitError:
+        raise SystemExit("error: failed to pull, dependent PRs have not been rebased")
+
+    # Build a map of branch names to their local commits
+    possible_shas = _get_possible_shas()
+
+    queue = collections.deque([branch_being_merged])
+    processed = set()
+
+    while queue:
+        base = queue.popleft()
+        if base in processed:
+            continue
+        processed.add(base)
+
+        # Find all PRs that target this base branch
+        dependent_branches = _get_prs_targeting_base(base)
+
+        for dep_branch in dependent_branches:
+            # Find the local commit for this dependent branch
+            dep_commit = _find_commit_for_branch(dep_branch, possible_shas)
+            if not dep_commit:
+                continue
+
+            # Rebase the dependent PR
+            if base == branch_being_merged:
+                _run_git_command(["rebasepr", dep_commit])
+            else:
+                _run_git_command(["rebasepr", dep_commit, base])
+
+            # Add this branch to the queue to process its dependents
+            queue.append(dep_branch)
+
+
+if __name__ == "__main__":
+    args = _build_parser().parse_args()
+    _main(args.commit)

bin/git-rebasepr

@@ -17,10 +17,10 @@ do
       ;;
     *)
       if [[ -n "$commit" ]]; then
-        echo "error: multiple commit args passed, '$commit' and '$arg'" >&2
-        exit 1
+        rebase_args+=("$arg")
+      else
+        commit="$arg"
       fi
-      commit="$arg"
       ;;
   esac
 done