Teach diff to imply --find-copies-harder upon -C -C

Earlier, a second "-C" on the command line had no effect.
But "--find-copies-harder" is so long to type, let's make doubled -C
enable that option.  It is in line with how "git blame" handles such
doubled options to mean "work harder".

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/diff.c b/diff.c
index 1d234d361..4aa9bbc01 100644
--- a/diff.c
+++ b/diff.c
@@ -2201,6 +2201,8 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		options->detect_rename = DIFF_DETECT_RENAME;
 	}
 	else if (!prefixcmp(arg, "-C")) {
+		if (options->detect_rename == DIFF_DETECT_COPY)
+			options->find_copies_harder = 1;
 		if ((options->rename_score =
 		     diff_scoreopt_parse(arg)) == -1)
 			return -1;