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

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

> 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.

> diff --git a/tree-diff.c b/tree-diff.c
> index 7a79660..3d08f78 100644
> --- a/tree-diff.c
> +++ b/tree-diff.c
> @@ -143,6 +143,7 @@ int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
>  
>  	for (;;) {
>  		if (DIFF_OPT_TST(opt, QUICK) &&
> +		    !opt->filter &&
>  		    DIFF_OPT_TST(opt, HAS_CHANGES))
>  			break;
>  		if (opt->pathspec.nr) {

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".