clangformat: Only format files tracked by git by default

docs/markdown/Code-formatting.md

@@ -56,3 +56,8 @@ Note that `.clang-format-ignore` has the same format as used by
 
 A new target `clang-format-check` has been added. It returns an error code if
 any file needs to be reformatted. This is intended to be used by CI.
+
+*Since 0.60.0*
+
+If `.clang-format-include` file is missing and source files are in a git
+repository, only files tracked by git will be included.

mesonbuild/scripts/clangformat.py

@@ -21,6 +21,7 @@ from concurrent.futures import ThreadPoolExecutor
 
 from ..environment import detect_clangformat
 from ..compilers import lang_suffixes
+from ..mesonlib import Popen_safe
 import typing as T
 
 def parse_pattern_file(fname: Path) -> T.List[str]:
@@ -52,9 +53,15 @@ def run_clang_format(exelist: T.List[str], fname: Path, check: bool) -> subproce
 
 def clangformat(exelist: T.List[str], srcdir: Path, builddir: Path, check: bool) -> int:
     patterns = parse_pattern_file(srcdir / '.clang-format-include')
-    if not patterns:
-        patterns = ['**/*']
-    globs = [srcdir.glob(p) for p in patterns]
+    globs: T.Union[T.List[T.List[Path]], T.List[T.Generator[Path, None, None]]]
+    if patterns:
+        globs = [srcdir.glob(p) for p in patterns]
+    else:
+        p, o, _ = Popen_safe(['git', 'ls-files'], cwd=srcdir)
+        if p.returncode == 0:
+            globs = [[Path(srcdir, f) for f in o.splitlines()]]
+        else:
+            globs = [srcdir.glob('**/*')]
     patterns = parse_pattern_file(srcdir / '.clang-format-ignore')
     ignore = [str(builddir / '*')]
     ignore.extend([str(srcdir / p) for p in patterns])
@@ -70,7 +77,8 @@ def clangformat(exelist: T.List[str], srcdir: Path, builddir: Path, check: bool)
                 any(fnmatch.fnmatch(strf, i) for i in ignore):
                 continue
             futures.append(e.submit(run_clang_format, exelist, f, check))
-        returncode = max(x.result().returncode for x in futures)
+        if futures:
+            returncode = max(x.result().returncode for x in futures)
     return returncode
 
 def run(args: T.List[str]) -> int:

unittests/allplatformstests.py

@@ -2539,6 +2539,7 @@ class AllPlatformTests(BasePlatformTests):
         testheader = os.path.join(testdir, 'header.h')
         badheader = os.path.join(testdir, 'header_orig_h')
         goodheader = os.path.join(testdir, 'header_expected_h')
+        includefile = os.path.join(testdir, '.clang-format-include')
         try:
             shutil.copyfile(badfile, testfile)
             shutil.copyfile(badheader, testheader)
@@ -2547,6 +2548,17 @@ class AllPlatformTests(BasePlatformTests):
                                 Path(goodfile).read_text(encoding='utf-8'))
             self.assertNotEqual(Path(testheader).read_text(encoding='utf-8'),
                                 Path(goodheader).read_text(encoding='utf-8'))
+
+            # test files are not in git so this should do nothing
+            self.run_target('clang-format')
+            self.assertNotEqual(Path(testfile).read_text(encoding='utf-8'),
+                                Path(goodfile).read_text(encoding='utf-8'))
+            self.assertNotEqual(Path(testheader).read_text(encoding='utf-8'),
+                                Path(goodheader).read_text(encoding='utf-8'))
+
+            # Add an include file to reformat everything
+            with open(includefile, 'w', encoding='utf-8') as f:
+                f.write('*')
             self.run_target('clang-format')
             self.assertEqual(Path(testheader).read_text(encoding='utf-8'),
                              Path(goodheader).read_text(encoding='utf-8'))
@@ -2555,6 +2567,8 @@ class AllPlatformTests(BasePlatformTests):
                 os.unlink(testfile)
             if os.path.exists(testheader):
                 os.unlink(testheader)
+            if os.path.exists(includefile):
+                os.unlink(includefile)
 
     @skipIfNoExecutable('clang-tidy')
     def test_clang_tidy(self):