Mach clippy & test-tidy github inline annotation (#37294)

When the --report-ci flag is passed to ./mach clippy or ./mach
test-tidy, the commands emit CI-friendly output to files in the tempy
directory. These files can later be used by [GitHub Workflow
Commands](https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/workflow-commands-for-github-actions#setting-an-error-message)
for annotations. If the flag is not provided, the default behavior
remains unchanged. Both clippy and test-tidy will limit have 10 limit
annotation

⚠️ Note: For ./mach clippy --report-ci to work correctly, the Clippy
command must use --message-format=json. If it's not specified, CI output
will not be generated, and no warning or error will be shown.

Example PR: https://github.com/jerensl/servo/pull/1/files

Fixes: #37231

---------

Signed-off-by: Jerens Lensun <jerensslensun@gmail.com>

.github/workflows/lint.yml

@@ -43,9 +43,8 @@ jobs:
         run: |
           sudo apt update
           ./mach bootstrap
-      # TODO: Do GitHub anotaions
       - name: Clippy
         run: |
-          ./mach clippy --use-crown --locked -- -- --deny warnings
+          ./mach clippy --use-crown --locked --github-annotations -- -- --deny warnings
       - name: Tidy
-        run: ./mach test-tidy --no-progress --all
+        run: ./mach test-tidy --no-progress --all --github-annotations

python/servo/command_base.py

@@ -10,8 +10,6 @@
 from __future__ import annotations
 
 import contextlib
-from enum import Enum
-from typing import Any, Dict, List, Optional
 import functools
 import gzip
 import itertools
@@ -24,24 +22,23 @@ import sys
 import tarfile
 import urllib
 import zipfile
-
 from dataclasses import dataclass
+from enum import Enum
 from errno import ENOENT as NO_SUCH_FILE_OR_DIRECTORY
 from glob import glob
 from os import path
 from subprocess import PIPE
+from typing import Any, Dict, List, Optional
 from xml.etree.ElementTree import XML
 
 import toml
-
 from mach.decorators import CommandArgument, CommandArgumentGroup
 from mach.registrar import Registrar
 
-from servo.platform.build_target import BuildTarget, AndroidTarget, OpenHarmonyTarget
-from servo.util import download_file, get_default_cache_dir
-
 import servo.platform
 import servo.util as util
+from servo.platform.build_target import AndroidTarget, BuildTarget, OpenHarmonyTarget
+from servo.util import download_file, get_default_cache_dir
 
 from python.servo.platform.build_target import SanitizerKind
 
@@ -804,6 +801,7 @@ class CommandBase(object):
         with_debug_assertions=False,
         with_frame_pointer=False,
         use_crown=False,
+        capture_output=False,
         target_override: Optional[str] = None,
         **_kwargs,
     ):
@@ -876,6 +874,9 @@ class CommandBase(object):
         # but uv venv on Windows only provides a `python`, not `python3`.
         env["PYTHON3"] = "python"
 
+        if capture_output:
+            return subprocess.run(["cargo", command] + args + cargo_args, env=env, capture_output=capture_output)
+
         return call(["cargo", command] + args + cargo_args, env=env, verbose=verbose)
 
     def android_adb_path(self, env):

python/servo/devenv_commands.py

@@ -7,20 +7,21 @@
 # option. This file may not be copied, modified, or distributed
 # except according to those terms.
 
-from os import path, listdir, getcwd
+import json
-
 import signal
 import subprocess
 import sys
 import tempfile
+from os import getcwd, listdir, path
 
 from mach.decorators import (
+    Command,
     CommandArgument,
     CommandProvider,
-    Command,
 )
+from tidy.linting_report import GitHubAnnotationManager
 
-from servo.command_base import CommandBase, cd, call
+from servo.command_base import CommandBase, call, cd
 
 
 @CommandProvider
@@ -108,8 +109,14 @@ class MachCommands(CommandBase):
 
     @Command("clippy", description='Run "cargo clippy"', category="devenv")
     @CommandArgument("params", default=None, nargs="...", help="Command-line arguments to be passed through to clippy")
+    @CommandArgument(
+        "--github-annotations",
+        default=False,
+        action="store_true",
+        help="Emit the clippy warnings in the Github Actions annotations format",
+    )
     @CommandBase.common_command_arguments(build_configuration=True, build_type=False)
-    def cargo_clippy(self, params, **kwargs):
+    def cargo_clippy(self, params, github_annotations=False, **kwargs):
         if not params:
             params = []
 
@@ -117,6 +124,23 @@ class MachCommands(CommandBase):
         self.ensure_clobbered()
         env = self.build_env()
         env["RUSTC"] = "rustc"
+
+        if github_annotations:
+            if "--message-format=json" not in params:
+                params.insert(0, "--message-format=json")
+
+            github_annotation_manager = GitHubAnnotationManager("clippy")
+
+            results = self.run_cargo_build_like_command("clippy", params, env=env, capture_output=True, **kwargs)
+            if results.returncode == 0:
+                return 0
+            try:
+                github_annotation_manager.emit_annotations_for_clippy(
+                    [json.loads(line) for line in results.stdout.splitlines() if line.strip()]
+                )
+            except json.JSONDecodeError:
+                pass
+            return results.returncode
         return self.run_cargo_build_like_command("clippy", params, env=env, **kwargs)
 
     @Command("grep", description="`git grep` for selected directories.", category="devenv")

python/servo/testing_commands.py

@@ -8,34 +8,32 @@
 # except according to those terms.
 
 import argparse
+import json
 import logging
-import re
-import sys
 import os
 import os.path as path
 import platform
+import re
 import shutil
 import subprocess
+import sys
 import textwrap
-import json
 
-import servo.devtools_tests
+import tidy
-from servo.post_build_commands import PostBuildCommands
 import wpt
 import wpt.manifestupdate
 import wpt.run
 import wpt.update
-
 from mach.decorators import (
+    Command,
     CommandArgument,
     CommandProvider,
-    Command,
 )
 
+import servo.devtools_tests
 import servo.try_parser
-import tidy
-
 from servo.command_base import BuildType, CommandBase, call, check_call
+from servo.post_build_commands import PostBuildCommands
 from servo.util import delete
 
 SCRIPT_PATH = os.path.split(__file__)[0]
@@ -254,8 +252,14 @@ class MachCommands(CommandBase):
         help="Check all files, and run the WPT lint in tidy, even if unchanged",
     )
     @CommandArgument("--no-progress", default=False, action="store_true", help="Don't show progress for tidy")
-    def test_tidy(self, all_files, no_progress):
+    @CommandArgument(
-        tidy_failed = tidy.scan(not all_files, not no_progress)
+        "--github-annotations",
+        default=False,
+        action="store_true",
+        help="Emit tidy warnings in the Github Actions annotations format",
+    )
+    def test_tidy(self, all_files, no_progress, github_annotations):
+        tidy_failed = tidy.scan(not all_files, not no_progress, github_annotations)
 
         print("\r ➤  Checking formatting of Rust files...")
         rustfmt_failed = format_with_rustfmt(check_only=True)

python/tidy/linting_report.py

@@ -0,0 +1,114 @@
+# Copyright 2025 The Servo Project Developers. See the COPYRIGHT
+# file at the top-level directory of this distribution.
+#
+# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+# option. This file may not be copied, modified, or distributed
+# except according to those terms.
+
+from dataclasses import dataclass
+from typing import Any, Literal, NotRequired
+
+
+@dataclass
+class GithubAnnotation:
+    file_name: str
+    line_start: int
+    line_end: int
+    level: Literal["notice", "warning", "error"]
+    title: str
+    message: str
+    column_start: NotRequired[int]
+    column_end: NotRequired[int]
+
+
+class GitHubAnnotationManager:
+    def __init__(self, annotation_prefix: str, limit: int = 10):
+        self.annotation_prefix: str = annotation_prefix
+        self.limit: int = limit
+        self.total_count: int = 0
+
+    def clean_path(self, path: str):
+        return path.removeprefix("./")
+
+    def escape(self, s: str):
+        return s.replace("\r", "%0D").replace("\n", "%0A")
+
+    def emit_annotation(
+        self,
+        title: str,
+        message: str,
+        file_name: str,
+        line_start: int,
+        line_end: int | None = None,
+        annotation_level: str = "error",
+        column_start: int | None = None,
+        column_end: int | None = None,
+    ):
+        if self.total_count >= self.limit:
+            return
+
+        if line_end is None:
+            line_end = line_start
+
+        annotation: GithubAnnotation = {
+            "title": f"{self.annotation_prefix}: {self.escape(title)}",
+            "message": self.escape(message),
+            "file_name": self.clean_path(file_name),
+            "line_start": line_start,
+            "line_end": line_end,
+            "level": annotation_level,
+        }
+
+        if line_start == line_end and column_start is not None and column_end is not None:
+            annotation["column_start"] = column_start
+            annotation["column_end"] = column_end
+
+        line_info = f"line={annotation['line_start']},endLine={annotation['line_end']},title={annotation['title']}"
+
+        column_info = ""
+        if "column_end" in annotation and "column_start" in annotation:
+            column_info = f"col={annotation['column_start']},endColumn={annotation['column_end']},"
+
+        print(
+            f"::{annotation['level']} file={annotation['file_name']},{column_info}{line_info}::{annotation['message']}"
+        )
+
+        self.total_count += 1
+
+    def emit_annotations_for_clippy(self, data: list[dict[str, Any]]):
+        severenty_map: dict[str, Literal["notice", "warning", "error"]] = {
+            "help": "notice",
+            "note": "notice",
+            "warning": "warning",
+            "error": "error",
+        }
+
+        for item in data:
+            if self.total_count >= self.limit:
+                break
+
+            message = item.get("message")
+            if not message:
+                continue
+
+            spans = message.get("spans") or []
+            primary_span = next((span for span in spans if span.get("is_primary")), None)
+            if not primary_span:
+                continue
+
+            annotation_level = severenty_map.get(message.get("level"), "error")
+            title = message.get("message", "")
+            rendered_message = message.get("rendered", "")
+
+            self.emit_annotation(
+                title,
+                rendered_message,
+                primary_span["file_name"],
+                primary_span["line_start"],
+                primary_span["line_end"],
+                annotation_level,
+                primary_span["column_start"],
+                primary_span["column_end"],
+            )

python/tidy/tidy.py

@@ -21,10 +21,10 @@ from typing import Any, Dict, List
 
 import colorama
 import toml
-
 import wpt.manifestupdate
 
-from .licenseck import OLD_MPL, MPL, APACHE, COPYRIGHT, licenses_toml
+from .licenseck import APACHE, COPYRIGHT, MPL, OLD_MPL, licenses_toml
+from .linting_report import GitHubAnnotationManager
 
 TOPDIR = os.path.abspath(os.path.dirname(sys.argv[0]))
 WPT_PATH = os.path.join(".", "tests", "wpt")
@@ -982,7 +982,8 @@ def collect_errors_for_files(files_to_check, checking_functions, line_checking_f
                     yield (filename,) + error
 
 
-def scan(only_changed_files=False, progress=False):
+def scan(only_changed_files=False, progress=False, github_annotations=False):
+    github_annotation_manager = GitHubAnnotationManager("test-tidy")
     # check config file for errors
     config_errors = check_config_file(CONFIG_FILE_PATH)
     # check directories contain expected files
@@ -1018,6 +1019,9 @@ def scan(only_changed_files=False, progress=False):
             + f"{colorama.Fore.RED}{error[2]}{colorama.Style.RESET_ALL}"
         )
 
+        if github_annotations:
+            github_annotation_manager.emit_annotation(error[2], error[2], error[0], error[1])
+
     return int(error is not None)