clang-format: ignore not staged hunks

09:28 <@sberg> vmiklos, I think I ran into a scenario last night where I had
both `git add`-ed and non-added changes in a non-blacklisted file, and the
non-added changes violated clang-format (and the added ones did not), and the
commit hook complained

So make sure we validate the index version, not the filesystem one.

(And modify a formatted file to trigger CI validation of the hook change
itself.)

Change-Id: I6431b35ac50dd03741104b5709c5195d6ff28632
Reviewed-on: https://gerrit.libreoffice.org/46368
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>

1 files changed, 10 insertions, 2 deletions

diff --git a/solenv/clang-format/ClangFormat.pm b/solenv/clang-format/ClangFormat.pm
index 1ec19ada2466..024fe7c1f87f 100644
--- a/solenv/clang-format/ClangFormat.pm
+++ b/solenv/clang-format/ClangFormat.pm
@@ -91,11 +91,19 @@ sub find()
     return $clang_format;
 }
 
-# Diffs the original and the formatted version of a single file.
+# Diffs the original and the formatted version of a single file from the index.
 sub check_style($$)
 {
+    # Make sure that not staged changes are not considered when diffing.
     my ($clang_format, $filename) = @_;
-    return system("'$clang_format' $filename | git --no-pager diff --no-index --exit-code $filename -") == 0;
+    my $index = $filename . ".index";
+    system("git show :$filename > $index");
+    my $format = $index . ".format";
+    system("'$clang_format' -assume-filename=$filename $index > $format");
+    my $ret = system("git --no-pager diff --no-index --exit-code $index $format") == 0;
+    unlink($index);
+    unlink($format);
+    return $ret;
 }
 
 # Private functions.