Re* [PATCH] diff-lib.c: Fix diff-files --diff-filter --quiet exit code

Junio C Hamano [off-list ref] writes:

The code notices that the caller, by specifying --quiet, does not want any
details of the changes and instead wants to know if there is a change or
not.  And it breaks out of the loop because it already found what it
wanted to know, namely, there is a change.

When you have a post-process filter (like -w or -S), the path we found to
be different here may be uninteresting and there may be no output (hence
we should exit with status 0).  So it is true that the optimization you
are removing needs to be disabled in _some_ situations, and the current
code doesn't, and it needs fixing.

What I was hinting at was perhaps to do it something like the attached; it
is totally untested, and merely for illustration purposes.

I didn't even try to cover -w/-S which may or may not involve inspecting
DIFF_FROM_CONTENTS bit in the options.

 diff-lib.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/diff-lib.c b/diff-lib.c
index 1e22992..2870de4 100644
--- a/diff-lib.c
+++ b/diff-lib.c

@@ -103,7 +103,8 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 		unsigned dirty_submodule = 0;
 
 		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))