Re: diff: --quiet does not imply --exit-code if --diff-filter is present

On Tue, May 31, 2011 at 08:46:29AM -0700, Junio C Hamano wrote:

Jeff King [off-list ref] writes:

quoted

Commit 2cfe8a6 (diff --quiet: disable optimization when
--diff-filter=X is used, 2011-03-16) fixes this in some
cases by disabling the optimization when a filter is
present. However, it only tweaked run_diff_files, missing
the similar case in diff_tree. Thus the fix worked only for
diffing the working tree and index, but not between trees.

Thanks; a natural question is if we need the same for diff-index, then.

No, it calls straight into unpack_trees. So I think the question is
"should unpack_trees respect the QUICK optimization". I suspect it
didn't happen simply because unpack_trees is so complex, and there are
probably corner cases with merging.

We probably want to have a helper in diff.c that does

	int diff_can_quit_early(struct diff_options *opt)
        {
        	return (DIFF_OPT_TST(opt, QUICK) &&
                	!opt->filter &&
                        DIFF_OPT_TST(opt, HAS_CHANGES));
	}

It is possible for us to later add new diffcore transformations that need
a similar "do not stop feeding early, as results may be filtered".

Yeah, that is a good refactoring. It's more readable, and it would have
prevented this bug. :)

-Peff