Re: [PATCH v3 3/5] diff: teach "--stat -w --exit-code" to notice differences

[Jeff King <peff@peff.net>]

On Fri, Aug 18, 2023 at 04:59:30PM -0700, Junio C Hamano wrote:

> Set the bit by inspecting the list of paths the diffstat output is
> given for (a mode-only change will still appear as a "0-line added
> 0-line deleted" change) to fix it.
> [...]
> diff --git a/diff.c b/diff.c
> index 998d7ae20c..da965ff688 100644
> --- a/diff.c
> +++ b/diff.c
> @@ -6901,6 +6901,7 @@ void compute_diffstat(struct diff_options *options,
>  		if (check_pair_status(p))
>  			diff_flush_stat(p, options, diffstat);
>  	}
> +	options->found_changes = !!diffstat->nr;
>  }

Makes sense, and this is delightfully simple. I wondered if we needed to
remove any code setting found_changes via builtin_diffstat(), but it
does not seem to exist in the first place. ;)

> diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
> index 02731dccb9..230a89b951 100755
> --- a/t/t4015-diff-whitespace.sh
> +++ b/t/t4015-diff-whitespace.sh
> @@ -11,7 +11,7 @@ TEST_PASSES_SANITIZE_LEAK=true
>  . ./test-lib.sh
>  . "$TEST_DIRECTORY"/lib-diff.sh
>  
> -for opts in --patch --quiet -s
> +for opts in --patch --quiet -s --stat --shortstat --dirstat=lines
>  do

I guess this would fix --numstat, too, though there may be diminishing
returns in checking every format if we know it is just hitting the same
code paths (though perhaps one could argue that --shortstat is already
uninteresting for the same reason).

-Peff