[llvm] [Workflow] Add new code format helper. (PR #66684)

[Tobias Hieta via llvm-commits]

================
@@ -0,0 +1,236 @@
+#!/usr/bin/env python3
+#
+# ====- code-format-helper, runs code formatters from the ci --*- python -*--==#
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+# ==-------------------------------------------------------------------------==#
+
+import argparse
+import os
+import subprocess
+import sys
+from functools import cached_property
+
+import github
+from github import IssueComment, PullRequest
+
+
+class FormatHelper:
+    COMMENT_TAG = "<!--LLVM CODE FORMAT COMMENT: {fmt}-->"
+    name = "unknown"
+
+    @property
+    def comment_tag(self) -> str:
+        return self.COMMENT_TAG.replace("fmt", self.name)
+
+    def format_run(self, changed_files: [str], args: argparse.Namespace) -> str | None:
+        pass
+
+    def pr_comment_text(self, diff: str) -> str:
+        return f"""
+{self.comment_tag}
+
+:warning: {self.friendly_name}, {self.name} found issues in your code. :warning:
+
+<details>
+<summary>
+You can test this locally with the following command:
+</summary>
+
+``````````bash
+{self.instructions}
+``````````
+
+</details>
+
+<details>
+<summary>
+View the diff from {self.name} here.
+</summary>
+
+``````````diff
+{diff}
+``````````
+
+</details>
+"""
+
+    def find_comment(
+        self, pr: PullRequest.PullRequest
+    ) -> IssueComment.IssueComment | None:
+        for comment in pr.as_issue().get_comments():
+            if self.comment_tag in comment.body:
+                return comment
+        return None
+
+    def update_pr(self, diff: str, args: argparse.Namespace):
+        repo = github.Github(args.token).get_repo(args.repo)
+        pr = repo.get_issue(args.issue_number).as_pull_request()
+
+        existing_comment = self.find_comment(pr)
+        pr_text = self.pr_comment_text(diff)
+
+        if existing_comment:
+            existing_comment.edit(pr_text)
+        else:
+            pr.as_issue().create_comment(pr_text)
+
+    def update_pr_success(self, args: argparse.Namespace):
+        repo = github.Github(args.token).get_repo(args.repo)
+        pr = repo.get_issue(args.issue_number).as_pull_request()
+
+        existing_comment = self.find_comment(pr)
+        if existing_comment:
+            existing_comment.edit(
+                f"""
+{self.comment_tag}
+:white_check_mark: With the latest revision this PR passed the {self.friendly_name}.
+"""
+            )
+
+    def run(self, changed_files: [str], args: argparse.Namespace):
+        diff = self.format_run(changed_files, args)
+        if diff:
+            self.update_pr(diff, args)
+            return False
+        else:
+            self.update_pr_success(args)
+            return True
+
+
+class ClangFormatHelper(FormatHelper):
+    name = "clang-format"
+    friendly_name = "C/C++ code formatter"
+
+    @property
+    def instructions(self):
+        return " ".join(self.cf_cmd)
+
----------------
tru wrote:

Actually - I tried this - and it becomes a bit complicated, if you want to pass two SHA's as we do you also have to pass `--diff`

So, if we want to reformat the local files we need more instructions to ensure that you are in the right branch on the right commit.

Are you ok with landing this as it is right now and we can iterate on the instructions later or make sure we link to external documentation?

https://github.com/llvm/llvm-project/pull/66684