Add --validate-rules, --dry-run, --comment-on-failure to land command

src/ghstack/cli.py

@@ -164,8 +164,29 @@ def cherry_pick(stack: bool, pull_request: str) -> None:
 
 @main.command("land")
 @click.option("--force", is_flag=True, help="force land even if the PR is closed")
+@click.option(
+    "--validate-rules",
+    is_flag=True,
+    help="validate against merge rules defined in .github/merge_rules.yaml",
+)
+@click.option(
+    "--dry-run",
+    is_flag=True,
+    help="validate merge rules but don't actually merge",
+)
+@click.option(
+    "--comment-on-failure",
+    is_flag=True,
+    help="post validation errors as a PR comment",
+)
 @click.argument("pull_request", metavar="PR")
-def land(force: bool, pull_request: str) -> None:
+def land(
+    force: bool,
+    validate_rules: bool,
+    dry_run: bool,
+    comment_on_failure: bool,
+    pull_request: str,
+) -> None:
     """
     Land a PR stack
     """
@@ -177,6 +198,9 @@ def land(force: bool, pull_request: str) -> None:
             github_url=config.github_url,
             remote_name=config.remote_name,
             force=force,
+            validate_rules=validate_rules,
+            dry_run=dry_run,
+            comment_on_failure=comment_on_failure,
         )
 
 

src/ghstack/land.py

@@ -2,11 +2,12 @@
 
 import logging
 import re
-from typing import List, Tuple
+from typing import List, Optional, Tuple
 
 import ghstack.git
 import ghstack.github
 import ghstack.github_utils
+import ghstack.merge_rules
 import ghstack.shell
 from ghstack.diff import PullRequestResolved
 from ghstack.types import GitCommitHash
@@ -50,6 +51,10 @@ def main(
     github_url: str,
     *,
     force: bool = False,
+    validate_rules: bool = False,
+    dry_run: bool = False,
+    comment_on_failure: bool = False,
+    rules_file: Optional[str] = None,
 ) -> None:
 
     # We land the entire stack pointed to by a URL.
@@ -60,19 +65,22 @@ def main(
     params = ghstack.github_utils.parse_pull_request(
         pull_request, sh=sh, remote_name=remote_name
     )
+    owner = params["owner"]
+    name = params["name"]
+
     default_branch = ghstack.github_utils.get_github_repo_info(
         github=github,
         sh=sh,
-        repo_owner=params["owner"],
-        repo_name=params["name"],
+        repo_owner=owner,
+        repo_name=name,
         github_url=github_url,
         remote_name=remote_name,
     )["default_branch"]
 
     needs_force = False
     try:
         protection = github.get(
-            f"repos/{params['owner']}/{params['name']}/branches/{default_branch}/protection"
+            f"repos/{owner}/{name}/branches/{default_branch}/protection"
         )
         if not protection["allow_force_pushes"]["enabled"]:
             raise RuntimeError(
@@ -91,12 +99,12 @@ def main(
 
     orig_ref, closed = lookup_pr_to_orig_ref_and_closed(
         github,
-        owner=params["owner"],
-        name=params["name"],
+        owner=owner,
+        name=name,
         number=params["number"],
     )
 
-    if closed:
+    if closed and not force:
         raise RuntimeError("PR is already closed, cannot land it!")
 
     if sh is None:
@@ -117,6 +125,64 @@ def main(
         github_url=github_url,
     )
 
+    # Compute the metadata for each commit
+    stack_orig_refs: List[Tuple[str, PullRequestResolved]] = []
+    for s in stack:
+        pr_resolved = s.pull_request_resolved
+        # We got this from GitHub, this better not be corrupted
+        assert pr_resolved is not None
+
+        ref, stack_closed = lookup_pr_to_orig_ref_and_closed(
+            github,
+            owner=pr_resolved.owner,
+            name=pr_resolved.repo,
+            number=pr_resolved.number,
+        )
+        if stack_closed and not force:
+            continue
+        stack_orig_refs.append((ref, pr_resolved))
+
+    # Validate merge rules if requested
+    if validate_rules:
+        logging.info("Validating merge rules for PR stack...")
+
+        # Load merge rules
+        loader = ghstack.merge_rules.MergeRulesLoader(github, owner, name)
+        if rules_file:
+            rules = loader.load_from_file(rules_file)
+        else:
+            rules = loader.load_from_repo()
+
+        if not rules:
+            logging.warning("No merge rules found, skipping validation")
+        else:
+            # Validate each PR in the stack
+            validator = ghstack.merge_rules.MergeValidator(github, owner, name)
+            for _, pr_resolved in stack_orig_refs:
+                result = validator.validate_pr(pr_resolved.number, rules)
+                if not result.valid:
+                    logging.error(
+                        f"Validation failed for PR #{pr_resolved.number}: "
+                        f"{', '.join(result.errors)}"
+                    )
+                    if comment_on_failure:
+                        comment_body = (
+                            ghstack.merge_rules.format_validation_error_comment(result)
+                        )
+                        github.post_issue_comment(
+                            owner, name, pr_resolved.number, comment_body
+                        )
+                    raise ghstack.merge_rules.MergeValidationError(result)
+                logging.info(
+                    f"PR #{pr_resolved.number} passed validation (rule: {result.rule_name})"
+                )
+
+            logging.info("All PRs in stack passed merge rules validation")
+
+        if dry_run:
+            logging.info("Dry run complete - no changes made")
+            return
+
     # Switch working copy
     try:
         prev_ref = sh.git("symbolic-ref", "--short", "HEAD")
@@ -127,23 +193,6 @@ def main(
     sh.git("checkout", f"{remote_name}/{default_branch}")
 
     try:
-        # Compute the metadata for each commit
-        stack_orig_refs: List[Tuple[str, PullRequestResolved]] = []
-        for s in stack:
-            pr_resolved = s.pull_request_resolved
-            # We got this from GitHub, this better not be corrupted
-            assert pr_resolved is not None
-
-            ref, closed = lookup_pr_to_orig_ref_and_closed(
-                github,
-                owner=pr_resolved.owner,
-                name=pr_resolved.repo,
-                number=pr_resolved.number,
-            )
-            if closed and not force:
-                continue
-            stack_orig_refs.append((ref, pr_resolved))
-
         # OK, actually do the land now
         for orig_ref, pr_resolved in stack_orig_refs:
             try: