Re: [PATCH v2] ref-filter.c: pass empty-string as NULL to atom parsers

> From: Taylor Blau <me@ttaylorr.com>
> Date: Mon, 2 Oct 2017 09:10:34 -0700
> Subject: [PATCH] ref-filter.c: pass empty-string as NULL to atom parsers
>
> Peff points out that different atom parsers handle the empty
> "sub-argument" list differently. An example of this is the format
> "%(refname:)".
>
> Since callers often use `string_list_split` (which splits the empty
> string with any delimiter as a 1-ary string_list containing the empty
> string), this makes handling empty sub-argument strings non-ergonomic.
>
> Let's fix this by declaring that atom parser implementations must
> not care about distinguishing between the empty string "%(refname:)"
> and no sub-arguments "%(refname)".  Current code aborts, either with
> "unrecognised arg" (e.g. "refname:") or "does not take args"
> (e.g. "body:") as an error message.
>
> Signed-off-by: Taylor Blau <me@ttaylorr.com>
> Reviewed-by: Jeff King <peff@peff.net>
> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  ref-filter.c            | 10 +++++++++-
>  t/t6300-for-each-ref.sh |  1 +
>  2 files changed, 10 insertions(+), 1 deletion(-)