Re: [PATCH v2] ref-filter.c: pass empty-string as NULL to atom parsers
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Oct 5, 2017, 01:49 UTC
- Message-ID
- <xmqq376y9xf7.fsf@gitster.mtv.corp.google.com>
- In-Reply-To
- <20171003033726.GA84817@D-10-157-251-166.dhcp4.washington.edu>
Taylor Blau <me@ttaylorr.com> writes:
Show 11 quoted lines
> On Tue, Oct 03, 2017 at 08:55:01AM +0900, Junio C Hamano wrote: >> Jonathan Nieder <jrnieder@gmail.com> writes: >> >> > The above does a nice job of explaining >> > >> > - what this change is going to do >> > - how it's good for the internal code structure / maintainability >> > >> > What it doesn't tell me about is why the user-facing effect won't >> > cause problems. Is there no atom where %(atom:) was previously >> > accepted and did something meaningful that this may break?
This loose end needs to be tied.
I replaced "let's assume that doing this change is OK" from the original log message with something a bit stronger, as with this change, we are saying that it is forbidden to treat %(atom) and %(atom:) differently. I also recorded the result of due-diligence survey of the current code to suggest that the change would be OK for current users.
-- >8 -- 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(-)
diff --git a/ref-filter.c b/ref-filter.c index bc591f4f3d..f3e53d4448 100644 --- a/ref-filter.c +++ b/ref-filter.c @@ -415,8 +415,16 @@ static int parse_ref_filter_atom(const struct ref_format *format, REALLOC_ARRAY(used_atom, used_atom_cnt); used_atom[at].name = xmemdupz(atom, ep - atom); used_atom[at].type = valid_atom[i].cmp_type; - if (arg) + if (arg) { arg = used_atom[at].name + (arg - atom) + 1; + if (!*arg) { + /* + * Treat empty sub-arguments list as NULL (i.e., + * "%(atom:)" is equivalent to "%(atom)"). + */ + arg = NULL; + } + } memset(&used_atom[at].u, 0, sizeof(used_atom[at].u)); if (valid_atom[i].parser) valid_atom[i].parser(format, &used_atom[at], arg); diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh index 2274a4b733..edc1bd8eab 100755 --- a/t/t6300-for-each-ref.sh +++ b/t/t6300-for-each-ref.sh @@ -51,6 +51,7 @@ test_atom() { } test_atom head refname refs/heads/master +test_atom head refname: refs/heads/master test_atom head refname:short master test_atom head refname:lstrip=1 heads/master test_atom head refname:lstrip=2 master
-- 2.14.2-921-g20a440a8ba