GH-109408: Move the C file whitespace check from patchcheck to pre-commit (#109890)

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>

3 files changed, 23 insertions, 90 deletions

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index aabf1c5..9a27d30 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -32,6 +32,21 @@ repos:
         types: [python]
         exclude: '^(Lib/test/tokenizedata/|Tools/c-analyzer/cpython/_parser).*$'
 
+  - repo: local
+    hooks:
+      - id: c-file-whitespace
+        name: "Check C file whitespace"
+        entry: "python Tools/patchcheck/untabify.py"
+        language: "system"
+        types_or: ['c', 'c++']
+        # Don't check the style of vendored libraries
+        exclude: |
+          (?x)^(
+            Modules/_decimal/.*
+            | Modules/libmpdec/.*
+            | Modules/expat/.*
+          )$
+
   - repo: https://github.com/sphinx-contrib/sphinx-lint
     rev: v0.6.8
     hooks:
diff --git a/Tools/patchcheck/patchcheck.py b/Tools/patchcheck/patchcheck.py
index 5f55e1b..66328c8 100755
--- a/Tools/patchcheck/patchcheck.py
+++ b/Tools/patchcheck/patchcheck.py
@@ -1,29 +1,15 @@
 #!/usr/bin/env python3
 """Check proposed changes for common issues."""
-import re
 import sys
-import shutil
 import os.path
 import subprocess
 import sysconfig
 
-import untabify
-
-
 def get_python_source_dir():
     src_dir = sysconfig.get_config_var('abs_srcdir')
     if not src_dir:
         src_dir = sysconfig.get_config_var('srcdir')
     return os.path.abspath(src_dir)
-
-
-# Excluded directories which are copies of external libraries:
-# don't check their coding style
-EXCLUDE_DIRS = [
-    os.path.join('Modules', '_decimal', 'libmpdec'),
-    os.path.join('Modules', 'expat'),
-    os.path.join('Modules', 'zlib'),
-    ]
 SRCDIR = get_python_source_dir()
 
 
@@ -154,47 +140,8 @@ def changed_files(base_branch=None):
     else:
         sys.exit('need a git checkout to get modified files')
 
-    filenames2 = []
-    for filename in filenames:
-        # Normalize the path to be able to match using .startswith()
-        filename = os.path.normpath(filename)
-        if any(filename.startswith(path) for path in EXCLUDE_DIRS):
-            # Exclude the file
-            continue
-        filenames2.append(filename)
-
-    return filenames2
-
-
-def report_modified_files(file_paths):
-    count = len(file_paths)
-    if count == 0:
-        return n_files_str(count)
-    else:
-        lines = [f"{n_files_str(count)}:"]
-        for path in file_paths:
-            lines.append(f"  {path}")
-        return "\n".join(lines)
-
-
-#: Python files that have tabs by design:
-_PYTHON_FILES_WITH_TABS = frozenset({
-    'Tools/c-analyzer/cpython/_parser.py',
-})
-
-
-@status("Fixing C file whitespace", info=report_modified_files)
-def normalize_c_whitespace(file_paths):
-    """Report if any C files """
-    fixed = []
-    for path in file_paths:
-        abspath = os.path.join(SRCDIR, path)
-        with open(abspath, 'r') as f:
-            if '\t' not in f.read():
-                continue
-        untabify.process(abspath, 8, verbose=False)
-        fixed.append(path)
-    return fixed
+    # Normalize the path to be able to match using str.startswith()
+    return list(map(os.path.normpath, filenames))
 
 
 @status("Docs modified", modal=True)
@@ -234,33 +181,12 @@ def regenerated_pyconfig_h_in(file_paths):
         return "not needed"
 
 
-def ci(pull_request):
-    if pull_request == 'false':
-        print('Not a pull request; skipping')
-        return
-    base_branch = get_base_branch()
-    file_paths = changed_files(base_branch)
-    c_files = [fn for fn in file_paths if fn.endswith(('.c', '.h'))]
-    fixed = []
-    fixed.extend(normalize_c_whitespace(c_files))
-    if not fixed:
-        print('No whitespace issues found')
-    else:
-        count = len(fixed)
-        print(f'Please fix the {n_files_str(count)} with whitespace issues')
-        print('(on Unix you can run `make patchcheck` to make the fixes)')
-        sys.exit(1)
-
-
 def main():
     base_branch = get_base_branch()
     file_paths = changed_files(base_branch)
-    c_files = [fn for fn in file_paths if fn.endswith(('.c', '.h'))]
     doc_files = [fn for fn in file_paths if fn.startswith('Doc') and
                  fn.endswith(('.rst', '.inc'))]
     misc_files = {p for p in file_paths if p.startswith('Misc')}
-    # C rules enforcement.
-    normalize_c_whitespace(c_files)
     # Docs updated.
     docs_modified(doc_files)
     # Misc/ACKS changed.
@@ -283,12 +209,4 @@ def main():
 
 
 if __name__ == '__main__':
-    import argparse
-    parser = argparse.ArgumentParser(description=__doc__)
-    parser.add_argument('--ci',
-                        help='Perform pass/fail checks')
-    args = parser.parse_args()
-    if args.ci:
-        ci(args.ci)
-    else:
-        main()
+    main()
diff --git a/Tools/patchcheck/untabify.py b/Tools/patchcheck/untabify.py
index 861c83c..5c9d120 100755
--- a/Tools/patchcheck/untabify.py
+++ b/Tools/patchcheck/untabify.py
@@ -21,8 +21,7 @@ def main():
         if optname == '-t':
             tabsize = int(optvalue)
 
-    for filename in args:
-        process(filename, tabsize)
+    return max(process(filename, tabsize) for filename in args)
 
 
 def process(filename, tabsize, verbose=True):
@@ -32,10 +31,10 @@ def process(filename, tabsize, verbose=True):
             encoding = f.encoding
     except IOError as msg:
         print("%r: I/O error: %s" % (filename, msg))
-        return
+        return 2
     newtext = text.expandtabs(tabsize)
     if newtext == text:
-        return
+        return 0
     backup = filename + "~"
     try:
         os.unlink(backup)
@@ -49,7 +48,8 @@ def process(filename, tabsize, verbose=True):
         f.write(newtext)
     if verbose:
         print(filename)
+    return 1
 
 
 if __name__ == '__main__':
-    main()
+    raise SystemExit(main())