[clang-format] Add return code to git-clang-format

#53220

Differential Revision: https://reviews.llvm.org/D117414

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

@@ -161,10 +161,12 @@ def main():
       print('Running clang-format on the following files:')
       for filename in changed_lines:
         print('    %s' % filename)
+
   if not changed_lines:
     if opts.verbose >= 0:
       print('no modified files to format')
-    return
+    return 0
+
   if len(commits) > 1:
     old_tree = commits[1]
     new_tree = run_clang_format_and_save_to_tree(changed_lines,
@@ -179,10 +181,13 @@ def main():
   if opts.verbose >= 1:
     print('old tree: %s' % old_tree)
     print('new tree: %s' % new_tree)
+
   if old_tree == new_tree:
     if opts.verbose >= 0:
       print('clang-format did not modify any files')
-  elif opts.diff:
+    return 0
+
+  if opts.diff:
     print_diff(old_tree, new_tree)
   elif opts.diffstat:
     print_diffstat(old_tree, new_tree)
@@ -194,6 +199,8 @@ def main():
       for filename in changed_files:
         print('    %s' % filename)
 
+  return 1
+
 
 def load_git_config(non_string_options=None):
   """Return the git configuration as a dictionary.