[clang-format] add support for cppm files

C++20 Modules current style is to assign a new file suffix .cppm.

#52658

Ensure git-clang-format can handle that as a default extension

Reviewed By: ChuanqiXu, HazardyKnusperkeks, curdeius

Differential Revision: https://reviews.llvm.org/D115625

Fixes: #52658

Author: mydeveloperday

clang/tools/clang-format/clang-format-diff.py

@@ -47,8 +47,8 @@ def main():
                       help='custom pattern selecting file paths to reformat '
                       '(case sensitive, overrides -iregex)')
   parser.add_argument('-iregex', metavar='PATTERN', default=
-                      r'.*\.(cpp|cc|c\+\+|cxx|c|cl|h|hh|hpp|hxx|m|mm|inc|js|ts'
-                      r'|proto|protodevel|java|cs|json)',
+                      r'.*\.(cpp|cc|c\+\+|cxx|cppm|ccm|cxxm|c\+\+m|c|cl|h|hh|hpp|hxx'
+                      r'|m|mm|inc|js|ts|proto|protodevel|java|cs|json)',
                       help='custom pattern selecting file paths to reformat '
                       '(case insensitive, overridden by -regex)')
   parser.add_argument('-sort-includes', action='store_true', default=False,

clang/tools/clang-format/git-clang-format

@@ -79,6 +79,7 @@ def main():
       'm',  # ObjC
       'mm',  # ObjC++
       'cc', 'cp', 'cpp', 'c++', 'cxx', 'hh', 'hpp', 'hxx',  # C++
+      'ccm', 'cppm', 'cxxm', 'c++m',  # C++ Modules
       'cu', 'cuh',  # CUDA
       # Other languages that clang-format supports
       'proto', 'protodevel',  # Protocol Buffers