[PATCH] diff --quiet: disable optimization when --diff-filter=X is used

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 16, 2011, 23:09 UTC
Message-ID: <7vmxku64sh.fsf_-_@alter.siamese.dyndns.org>
In-Reply-To: <7vwrjy670r.fsf_-_@alter.siamese.dyndns.org>

The code notices that the caller does not want any detail of the changes and only wants to know if there is a change or not by specifying --quiet. And it breaks out of the loop when it knows it already found any change.

When you have a post-process filter (e.g. --diff-filter), however, the path we found to be different in the previous round and set HAS_CHANGES bit may end up being uninteresting, and there may be no output at the end. The optimization needs to be disabled for such case.

Note that the f245194 (diff: change semantics of "ignore whitespace" options, 2009-05-22) already disables this optimization by refraining from setting HAS_CHANGES when post-process filters that need to inspect the contents of the files (e.g. -S, -w) in diff_change() function.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

 * This time with tests, on top of 90b1994 (diff: Rename QUIET internal
   option to QUICK, 2009-05-23), which was the last commit in the series
   that introduced the incorrect optimization in the first place.

   Note that the test script was renamed to t/t4040 in today's codebase,
   but it merges cleanly.

 diff-lib.c                   |    3 ++-
 t/t4037-whitespace-status.sh |    7 +++++++
 2 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/diff-lib.c b/diff-lib.c
index b7813af..bfa6503 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -74,7 +74,8 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 		int changed;
 
 		if (DIFF_OPT_TST(&revs->diffopt, QUICK) &&
-			DIFF_OPT_TST(&revs->diffopt, HAS_CHANGES))
+		    !revs->diffopt.filter &&
+		    DIFF_OPT_TST(&revs->diffopt, HAS_CHANGES))
 			break;
 
 		if (!ce_path_match(ce, revs->prune_data))
diff --git a/t/t4037-whitespace-status.sh b/t/t4037-whitespace-status.sh
index a30b03b..abc4934 100755
--- a/t/t4037-whitespace-status.sh
+++ b/t/t4037-whitespace-status.sh
@@ -60,4 +60,11 @@ test_expect_success 'diff-files -b -p --exit-code' '
 	git diff-files -b -p --exit-code
 '
 
+test_expect_success 'diff-files --diff-filter --quiet' '
+	git reset --hard &&
+	rm a/d &&
+	echo x >>b/e &&
+	test_must_fail git diff-files --diff-filter=M --quiet
+'
+
 test_done

-- 
1.7.4.1.430.g5aa4d