Add autoformatting for Bazel files

.github/workflows/lint.yml

@@ -21,6 +21,8 @@ jobs:
           chmod +x llvm.sh
           sudo ./llvm.sh 18
           sudo apt-get install -y --no-install-recommends clang-format-18
+          # buildifier won't install properly if specifying a particular version
+          go install github.com/bazelbuild/buildtools/buildifier@latest
       - name: Install pnpm
         uses: pnpm/action-setup@v4
         # The pnpm version will be determined by the `packageManager` field in `.npmrc`

tools/cross/format.py

@@ -6,11 +6,15 @@
 import subprocess
 from argparse import ArgumentParser, Namespace
 from typing import List, Optional, Tuple, Callable
+from pathlib import Path
 from dataclasses import dataclass
 
 
 CLANG_FORMAT = os.environ.get("CLANG_FORMAT", "clang-format")
 PRETTIER = os.environ.get("PRETTIER", "node_modules/.bin/prettier")
+BUILDIFIER = os.environ.get(
+    "BUILDIFIER", Path(os.environ.get("HOME", "/")) / "go/bin/buildifier"
+)
 
 
 def parse_args() -> Namespace:
@@ -58,11 +62,16 @@ def parse_args() -> Namespace:
     return options
 
 
-def check_clang_format() -> bool:
+def check_clang_format() -> None:
     try:
         # Run clang-format with --version to check its version
         output = subprocess.check_output([CLANG_FORMAT, "--version"], encoding="utf-8")
-        major, _, _ = re.search(r"version\s*(\d+)\.(\d+)\.(\d+)", output).groups()
+        match = re.search(r"version\s*(\d+)\.(\d+)\.(\d+)", output)
+        if not match:
+            logging.error("unable to read clang version")
+            exit(1)
+
+        major, _, _ = match.groups()
         if int(major) != 18:
             logging.error("clang-format version must be 18")
             exit(1)
@@ -72,17 +81,30 @@ def check_clang_format() -> bool:
         exit(1)
 
 
-def filter_files_by_exts(
-    files: List[str], dir_path: str, exts: Tuple[str, ...]
-) -> List[str]:
+def filter_files_by_globs(
+    files: List[Path], dir_path: Path, globs: Tuple[str, ...]
+) -> List[Path]:
     return [
         file
         for file in files
-        if file.startswith(dir_path + "/") and file.endswith(exts)
+        if is_relative_to(file, dir_path) and matches_any_glob(globs, file)
     ]
 
 
-def clang_format(files: List[str], check: bool = False) -> bool:
+def matches_any_glob(globs: Tuple[str, ...], file: Path) -> bool:
+    return any(file.match(glob) for glob in globs)
+
+
+def is_relative_to(path: Path, prefix: Path) -> bool:
+    # Polyfill for method introduced in Python 3.9
+    try:
+        path.relative_to(prefix)
+        return True
+    except ValueError:
+        return False
+
+
+def clang_format(files: List[Path], check: bool = False) -> bool:
     cmd = [CLANG_FORMAT, "--verbose"]
     if check:
         cmd += ["--dry-run", "--Werror"]
@@ -92,25 +114,27 @@ def clang_format(files: List[str], check: bool = False) -> bool:
     return result.returncode == 0
 
 
-def prettier(files: List[str], check: bool = False) -> bool:
-    cmd = [PRETTIER]
-    if check:
-        cmd.append("--check")
-    else:
-        cmd.append("--write")
+def prettier(files: List[Path], check: bool = False) -> bool:
+    cmd = [PRETTIER, "--check" if check else "--write"]
+    result = subprocess.run(cmd + files)
+    return result.returncode == 0
+
+
+def buildifier(files: List[Path], check: bool = False) -> bool:
+    cmd = [BUILDIFIER, "--mode=check" if check else "--mode=fix"]
     result = subprocess.run(cmd + files)
     return result.returncode == 0
 
 
 def git_get_modified_files(
     target: str, source: Optional[str], staged: bool
-) -> List[str]:
+) -> List[Path]:
     if staged:
         files_in_diff = subprocess.check_output(
             ["git", "diff", "--diff-filter=d", "--name-only", "--cached"],
             encoding="utf-8",
         ).splitlines()
-        return files_in_diff
+        return [Path(file) for file in files_in_diff]
     else:
         merge_base = subprocess.check_output(
             ["git", "merge-base", target, source or "HEAD"], encoding="utf-8"
@@ -120,53 +144,56 @@ def git_get_modified_files(
             + ([source] if source else []),
             encoding="utf-8",
         ).splitlines()
-        return files_in_diff
+        return [Path(file) for file in files_in_diff]
 
 
-def git_get_all_files() -> List[str]:
-    return subprocess.check_output(
+def git_get_all_files() -> List[Path]:
+    files = subprocess.check_output(
         ["git", "ls-files", "--cached", "--others", "--exclude-standard"],
         encoding="utf-8",
     ).splitlines()
+    return [Path(file) for file in files]
 
 
 @dataclass
 class FormatConfig:
     directory: str
-    extensions: Tuple[str, ...]
-    formatter: Callable[[List[str], bool], bool]
+    globs: Tuple[str, ...]
+    formatter: Callable[[List[Path], bool], bool]
 
 
 FORMATTERS = [
     FormatConfig(
-        directory="src/workerd", extensions=(".c++", ".h"), formatter=clang_format
+        directory="src/workerd", globs=("*.c++", "*.h"), formatter=clang_format
     ),
     FormatConfig(
         directory="src",
-        extensions=(".js", ".ts", ".cjs", ".ejs", ".mjs"),
+        globs=("*.js", "*.ts", "*.cjs", "*.ejs", "*.mjs"),
         formatter=prettier,
     ),
-    FormatConfig(directory="src", extensions=(".json",), formatter=prettier),
-    # TODO: lint bazel files
+    FormatConfig(directory="src", globs=("*.json",), formatter=prettier),
+    FormatConfig(
+        directory=".",
+        globs=("*.bzl", "*.bazel", "WORKSPACE", "BUILD", "BUILD.*"),
+        formatter=buildifier,
+    ),
 ]
 
 
-def format(config: FormatConfig, files: List[str], check: bool) -> bool:
-    matching_files = filter_files_by_exts(files, config.directory, config.extensions)
+def format(config: FormatConfig, files: List[Path], check: bool) -> bool:
+    matching_files = filter_files_by_globs(files, Path(config.directory), config.globs)
 
     if not matching_files:
         return True
 
     return config.formatter(matching_files, check)
 
 
-def main():
+def main() -> None:
     options = parse_args()
     check_clang_format()
     if options.subcommand == "git":
-        files = set(
-            git_get_modified_files(options.target, options.source, options.staged)
-        )
+        files = git_get_modified_files(options.target, options.source, options.staged)
     else:
         files = git_get_all_files()