Bug 1514770 - hooks_clang_format for git: Run clang-format on the changed files r=sheehan

Depends on D23789

Differential Revision: https://phabricator.services.mozilla.com/D23798

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

tools/lint/hooks_clang_format.py

@@ -5,6 +5,7 @@
 
 import os
 import subprocess
+from subprocess import check_output, CalledProcessError
 import sys
 
 here = os.path.dirname(os.path.realpath(__file__))
@@ -16,18 +17,17 @@ sys.path[:0] = [os.path.join(topsrcdir, p) for p in EXTRA_PATHS]
 from mozversioncontrol import get_repository_object, InvalidRepoPath
 
 
-def run_clang_format(hooktype, args):
+def run_clang_format(hooktype, changedFiles):
     try:
         vcs = get_repository_object(topsrcdir)
     except InvalidRepoPath:
         return
 
-    changedFiles = vcs.get_outgoing_files("AM")
     if not changedFiles:
         # No files have been touched
         return
 
-    arguments = ["clang-format", "-s", "-p"] + changedFiles
+    arguments = ["clang-format", "-p"] + changedFiles
     # 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
@@ -35,9 +35,10 @@ def run_clang_format(hooktype, args):
         clang_format_cmd = [os.path.join(topsrcdir, "mach")] + arguments
     if "commit" in hooktype:
         # don't prevent commits, just display the clang-format results
-        subprocess.Popen(clang_format_cmd)
+        subprocess.call(clang_format_cmd)
+        # Add the modified files back to the repo (expect a string)
+        vcs.add_remove_files(" ".join(changedFiles))
         return False
-
     print("warning: '{}' is not a valid clang-format hooktype".format(hooktype))
     return False
 
@@ -56,7 +57,17 @@ def git():
     hooktype = os.path.basename(__file__)
     if hooktype == "hooks_clang_format.py":
         hooktype = "pre-push"
-    return run_clang_format(hooktype, [])
+
+    try:
+        changedFiles = check_output(
+            ["git", "diff", "--staged", "--name-only", "HEAD"]
+        ).split()
+        # TODO we should detect if we are in a "add -p" mode and show a warning
+        return run_clang_format(hooktype, changedFiles)
+
+    except CalledProcessError:
+        print("Command to retrieve local files failed")
+        return 1
 
 
 if __name__ == "__main__":