Add github job for checking code formatting

.github/workflows/lint.yml

@@ -0,0 +1,32 @@
+# Copyright 2022 The IREE Authors
+#
+# Licensed 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
+
+name: Lint
+
+on: [pull_request]
+
+jobs:
+  yapf:
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Checking out repository
+        uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # v3.3.0
+      - name: Setting up python
+        uses: actions/setup-python@d27e3f3d7c64b4bbf8e4abfb9b63b83e846e0435 # v4.5.0
+      - name: Fetching Base Branch
+        # We have to explicitly fetch the base branch as well
+        run: git fetch --no-tags --prune --depth=1 origin "${GITHUB_BASE_REF?}:${GITHUB_BASE_REF?}"
+      - name: Install yapf
+        run: |
+          python3 -m pip install yapf==0.32.0
+      - name: Run format_diff.py with yapf
+        run: |
+          git diff -U0 "${GITHUB_BASE_REF?}" | python3 third_party/format_diff/format_diff.py yapf -i
+          git diff --exit-code
+      - name: Instructions for fixing the above linting errors
+        if: ${{ failure() }}
+        run: |
+          printf "You can fix the lint errors above by running\n"

third_party/format_diff/README.md

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+Forked from https://github.com/llvm/llvm-project/blob/master/clang/tools/clang-format/clang-format-diff.py

third_party/format_diff/format_diff.py

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+#!/usr/bin/env python3
+#
+#===- format_diff.py - Diff Reformatter ----*- python3 -*--===#
+#
+# This file is licensed 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
+#
+#===------------------------------------------------------------------------===#
+"""
+This script reads input from a unified diff and reformats all the changed
+lines. This is useful to reformat all the lines touched by a specific patch.
+Example usage:
+
+  git diff -U0 HEAD^ | python3 format_diff.py yapf -i
+  git diff -U0 HEAD^ | python3 format_diff.py clang-format -i
+  svn diff --diff-cmd=diff -x-U0 | python3 format_diff.py -p0 clang-format -i
+
+General usage:
+  <some diff> | python3 format_diff.py [--regex] [--lines-style] [-p] binary [args for binary]
+
+It should be noted that the filename contained in the diff is used unmodified
+to determine the source file to update. Users calling this script directly
+should be careful to ensure that the path in the diff is correct relative to the
+current working directory.
+"""
+
+import argparse
+import difflib
+import io
+import re
+import subprocess
+import sys
+
+BINARY_TO_DEFAULT_REGEX = {
+    "yapf": r".*\.py",
+    "clang-format":
+        r".*\.(cpp|cc|c\+\+|cxx|c|cl|h|hh|hpp|hxx|m|mm|inc|js|ts|proto|"
+        r"protodevel|java|cs)",
+}
+
+
+def parse_arguments():
+  parser = argparse.ArgumentParser(
+      description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
+  parser.add_argument(
+      "binary",
+      help="Location of binary to use for formatting. This controls the "
+      "default values of --regex and --lines-style. If binary isn't 'yapf' "
+      "or 'clang-format' then --regex and --lines-style are required.")
+  parser.add_argument(
+      "--regex",
+      metavar="PATTERN",
+      default=None,
+      help="Regex pattern for selecting file paths to reformat from the piped "
+      "diff. This flag is required if 'binary' is not set to 'yapf' or "
+      "'clang-format'. Otherwise, this flag overrides the default pattern that "
+      "--binary sets.")
+  parser.add_argument(
+      "--lines-style",
+      default=None,
+      help="How to style the 'lines' argument for the given binary. Can be set "
+      "to 'yapf' or 'clang-format'. This flag is required if 'binary' is not "
+      "set to 'yapf' or 'clang-format'.")
+  parser.add_argument(
+      "-p",
+      metavar="NUM",
+      default=1,
+      help="Strip the smallest prefix containing P slashes. Set to 0 if "
+      "passing `--no-prefix` to `git diff` or using `svn`")
+
+  # Parse and error-check arguments
+  args, binary_args = parser.parse_known_args()
+  if args.binary not in BINARY_TO_DEFAULT_REGEX:
+    if not args.regex:
+      raise parser.error("If 'binary' is not 'yapf' or 'clang-format' then "
+                         "--regex must be set.")
+    if not args.lines_style:
+      raise parser.error("If 'binary' is not 'yapf' or 'clang-format' then "
+                         "--lines-style must be set.")
+  else:
+    # Set defaults based off of 'binary'.
+    if not args.regex:
+      args.regex = BINARY_TO_DEFAULT_REGEX[args.binary]
+    if not args.lines_style:
+      args.lines_style = args.binary
+
+  if args.lines_style not in ["yapf", "clang-format"]:
+    raise parser.error(f"Unexpected value for --line-style {args.lines_style}")
+
+  return args, binary_args
+
+
+def main():
+  args, binary_args = parse_arguments()
+
+  # Extract changed lines for each file.
+  filename = None
+  lines_by_file = {}
+  for line in sys.stdin:
+    # Match all filenames.
+    match = re.search(fr"^\+\+\+\ (.*?/){{{args.p}}}(\S*)", line)
+    if match:
+      filename = match.group(2)
+    if filename is None:
+      continue
+
+    # Match all filenames specified by --regex.
+    if not re.match(f"^{args.regex}$", filename):
+      continue
+
+    # Match unified diff line numbers.
+    match = re.search(r"^@@.*\+(\d+)(,(\d+))?", line)
+    if match:
+      start_line = int(match.group(1))
+      line_count = 1
+      if match.group(3):
+        line_count = int(match.group(3))
+      if line_count == 0:
+        continue
+      end_line = start_line + line_count - 1
+
+      if args.lines_style == "yapf":
+        lines = ["--lines", f"{start_line}-{end_line}"]
+      elif args.lines_style == "clang-format":
+        lines = ["-lines", f"{start_line}:{end_line}"]
+      lines_by_file.setdefault(filename, []).extend(lines)
+
+  # Pass the changed lines to 'binary' alongside any unparsed args (e.g. -i).
+  for filename, lines in lines_by_file.items():
+    command = [args.binary, filename]
+    command.extend(lines)
+    command.extend(binary_args)
+
+    print(f"Running `{' '.join(command)}`")
+    p = subprocess.Popen(command,
+                         stdout=subprocess.PIPE,
+                         stderr=None,
+                         stdin=subprocess.PIPE,
+                         universal_newlines=True)
+    stdout, stderr = p.communicate()
+    if p.returncode != 0:
+      sys.exit(p.returncode)
+
+    # If the formatter printed the formatted code to stdout then print out
+    # a unified diff between the formatted and unformatted code.
+    # If flags like --verbose are passed to the binary then the diffs this
+    # produces won't be particularly helpful.
+    formatted_code = io.StringIO(stdout).readlines()
+    if len(formatted_code):
+      with open(filename) as f:
+        unformatted_code = f.readlines()
+      diff = difflib.unified_diff(unformatted_code,
+                                  formatted_code,
+                                  fromfile=filename,
+                                  tofile=filename,
+                                  fromfiledate="(before formatting)",
+                                  tofiledate="(after formatting)")
+      diff_string = "".join(diff)
+      if len(diff_string) > 0:
+        sys.stdout.write(diff_string)
+
+
+if __name__ == "__main__":
+  main()