From: Jeff King <peff@peff.net>
To: "René Scharfe" <l.s.r@web.de>
Cc: Junio C Hamano <gitster@pobox.com>, Git List <git@vger.kernel.org>
Subject: Re: [PATCH] describe: fix --no-exact-match
Date: Fri, 11 Aug 2023 11:11:02 -0400 [thread overview]
Message-ID: <20230811151102.GE2303200@coredump.intra.peff.net> (raw)
In-Reply-To: <09f499ad-28a5-0d8b-8af6-97475bdc614b@web.de>
On Thu, Aug 10, 2023 at 09:10:33PM +0200, René Scharfe wrote:
> > I'm not sure there's a portable and non-insane way of doing what we want
> > here. At least at compile-time.
>
> We need a wrapper with the correct signature. The wrapper is plugged
> into struct option. The typed callback is called by the wrapper and
> can be used for a type check in the struct macro. Demo patch below.
OK, clever. So we have two functions, one with a real body, and the
other which is used with the void pointer. How do we make sure that the
real-body one matches the type passed to OPT_CALLBACK(), if it is only
seeing the void wrapper? I guess that is this bit in short_name:
> +#define OPT_CALLBACK_F_T(s, l, v, a, h, f, cb) { \
> + .type = OPTION_CALLBACK, \
> + .short_name = (s) + (0 ? cb(NULL, NULL, 0, (v)) : 0), \
which would cause the compiler to barf, and presumably eliminate the
dead code (or at the very least never call it at runtime).
So I think that works. Though...
> +#define DEFINE_PARSE_OPT_CB(name) \
> +static inline int name ## __void(const struct option *opt, \
> + const char *arg, int unset) \
> +{ \
> + return name(opt, arg, unset, opt->value); \
> +} \
we are defining an inline function with the explicit goal of passing it
as a function pointer. I don't remember all of the standard's rules
here. Are we guaranteed that it will create a linkable version if
necessary?
We could probably drop the "inline" (and perhaps would need to add
MAYBE_UNUSED in such a case).
> diff --git a/builtin/describe.c b/builtin/describe.c
> index b28a4a1f82..ce16c36de2 100644
> --- a/builtin/describe.c
> +++ b/builtin/describe.c
> @@ -558,15 +558,17 @@ static void describe(const char *arg, int last_one)
> strbuf_release(&sb);
> }
>
> -static int option_parse_exact_match(const struct option *opt, const char *arg,
> - int unset)
> +static int option_parse_exact_match(const struct option *opt UNUSED,
> + const char *arg, int unset, int *value)
> {
> BUG_ON_OPT_ARG(arg);
>
> - max_candidates = unset ? DEFAULT_CANDIDATES : 0;
> + *value = unset ? DEFAULT_CANDIDATES : 0;
> return 0;
> }
>
> +DEFINE_PARSE_OPT_CB(option_parse_exact_match);
I wondered about combining these, like:
DEFINE_PARSE_OPT_CB(option_parse_exact_match, int) {
...the real body here...
}
But I guess that may confuse non-compiler parsers, and it doesn't leave
room for annotations like the UNUSED above (which ironically is still
needed, since now we pass opt->value as its own parameter).
So I dunno. Clever, for sure, and I think it would work. I'm not sure if
the extra code merits the return or not.
-Peff
next prev parent reply other threads:[~2023-08-11 15:11 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-18 15:44 [PATCH] ls-tree: fix --no-full-name René Scharfe
2023-07-18 16:37 ` Junio C Hamano
2023-07-18 20:49 ` Junio C Hamano
2023-07-21 12:41 ` René Scharfe
2023-07-21 12:41 ` René Scharfe
2023-07-21 14:37 ` Junio C Hamano
2023-07-21 19:29 ` René Scharfe
2023-07-21 20:09 ` Junio C Hamano
2023-07-21 20:14 ` Junio C Hamano
2023-07-24 12:29 ` René Scharfe
2023-07-24 18:51 ` Junio C Hamano
2023-07-24 20:09 ` René Scharfe
2023-07-24 20:50 ` Junio C Hamano
2023-07-28 6:12 ` René Scharfe
2023-07-28 9:45 ` Phillip Wood
2023-07-29 20:40 ` René Scharfe
2023-07-31 15:31 ` Junio C Hamano
2023-08-04 16:40 ` Junio C Hamano
2023-08-04 19:48 ` Phillip Wood
2023-08-05 10:40 ` René Scharfe
2023-07-24 12:29 ` [PATCH v2 0/5] show negatability of options in short help René Scharfe
2023-07-24 12:34 ` [PATCH v2 1/5] subtree: disallow --no-{help,quiet,debug,branch,message} René Scharfe
2023-07-24 12:36 ` [PATCH v2 2/5] t1502, docs: disallow --no-help René Scharfe
2023-07-24 12:38 ` [PATCH v2 3/5] t1502: move optionspec help output to a file René Scharfe
2023-07-24 12:39 ` [PATCH v2 4/5] t1502: test option negation René Scharfe
2023-07-24 12:40 ` [PATCH v2 5/5] parse-options: show negatability of options in short help René Scharfe
2023-08-05 14:33 ` [PATCH v3 0/8] " René Scharfe
2023-08-05 14:37 ` [PATCH v3 1/8] subtree: disallow --no-{help,quiet,debug,branch,message} René Scharfe
2023-08-05 14:37 ` [PATCH v3 2/8] t1502, docs: disallow --no-help René Scharfe
2023-08-05 14:38 ` [PATCH v3 3/8] t1502: move optionspec help output to a file René Scharfe
2023-08-05 14:39 ` [PATCH v3 4/8] t1502: test option negation René Scharfe
2023-08-05 14:40 ` [PATCH v3 5/8] parse-options: show negatability of options in short help René Scharfe
2023-08-05 14:43 ` [PATCH v3 6/8] parse-options: factor out usage_indent() and usage_padding() René Scharfe
2023-08-05 14:44 ` [PATCH v3 7/8] parse-options: no --[no-]no- René Scharfe
2023-08-05 14:52 ` [PATCH v3 8/8] parse-options: simplify usage_padding() René Scharfe
2023-08-05 23:04 ` Junio C Hamano
2023-07-21 12:41 ` [PATCH] show-branch: fix --no-sparse René Scharfe
2023-07-21 14:42 ` Junio C Hamano
2023-07-21 16:30 ` René Scharfe
2023-07-21 12:41 ` [PATCH] show-branch: disallow --no-{date,topo}-order René Scharfe
2023-07-21 12:41 ` [PATCH] reset: disallow --no-{mixed,soft,hard,merge,keep} René Scharfe
2023-07-21 12:41 ` [PATCH] pack-objects: fix --no-quiet René Scharfe
2023-07-21 12:41 ` [PATCH] pack-objects: fix --no-keep-true-parents René Scharfe
2023-07-21 17:03 ` Junio C Hamano
2023-07-21 12:42 ` [PATCH] branch: disallow --no-{all,remotes} René Scharfe
2023-07-21 12:42 ` [PATCH] am: unify definition of --keep-cr and --no-keep-cr René Scharfe
2023-07-21 13:41 ` [PATCH] describe: fix --no-exact-match René Scharfe
2023-07-21 14:10 ` Junio C Hamano
2023-07-21 17:00 ` Junio C Hamano
2023-08-08 21:27 ` Jeff King
2023-08-08 21:28 ` Jeff King
2023-08-09 1:43 ` Junio C Hamano
2023-08-09 14:09 ` Jeff King
2023-08-09 16:41 ` René Scharfe
2023-08-09 19:07 ` Junio C Hamano
2023-08-10 0:26 ` Jeff King
2023-08-10 1:00 ` Junio C Hamano
2023-08-10 19:45 ` René Scharfe
2023-08-10 0:41 ` Jeff King
2023-08-10 19:10 ` René Scharfe
2023-08-11 15:11 ` Jeff King [this message]
2023-08-11 17:59 ` René Scharfe
2023-08-11 18:24 ` Jeff King
2023-08-12 5:11 ` René Scharfe
2023-08-11 15:13 ` Jeff King
2023-08-11 17:59 ` René Scharfe
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