Bug 1542629 - clang-format git hook: Ignore unsupported extensions directly in the hook r=sheehan

Differential Revision: https://phabricator.services.mozilla.com/D26445

--HG--
extra : moz-landing-system : lando

tools/lint/hooks_clang_format.py

@@ -27,7 +27,23 @@ def run_clang_format(hooktype, changedFiles):
         # No files have been touched
         return
 
-    arguments = ["clang-format", "-p"] + changedFiles
+    # We have also a copy of this list in:
+    # python/mozbuild/mozbuild/mach_commands.py
+    # version-control-tools/hgext/clang-format/__init__.py
+    # release-services/src/staticanalysis/bot/static_analysis_bot/config.py
+    # Too heavy to import the full class just for this variable
+    extensions = (".cpp", ".c", ".cc", ".h", ".m", ".mm")
+    path_list = []
+    for filename in sorted(changedFiles):
+        # Ignore files unsupported in clang-format
+        if filename.endswith(extensions):
+            path_list.append(filename)
+
+    if not path_list:
+        # No files have been touched
+        return
+
+    arguments = ["clang-format", "-p"] + path_list
     # On windows we need this to call the command in a shell, see Bug 1511594
     if os.name == "nt":
         clang_format_cmd = ["sh", "mach"] + arguments
@@ -39,7 +55,7 @@ def run_clang_format(hooktype, changedFiles):
 
         # Add the modified files back to the repo (expect a string)
         # one by one (fails otherwise, see bug #1541409)
-        for f in changedFiles:
+        for f in path_list:
             vcs.add_remove_files(f)
 
         return False