From: "René Scharfe" <l.s.r@web.de>
To: Jeff King <peff@peff.net>
Cc: Junio C Hamano <gitster@pobox.com>, Git List <git@vger.kernel.org>
Subject: Re: [PATCH] describe: fix --no-exact-match
Date: Sat, 12 Aug 2023 07:11:03 +0200 [thread overview]
Message-ID: <6e05309d-c2be-c949-ae83-c4dd3247e790@web.de> (raw)
In-Reply-To: <20230811182415.GC2816191@coredump.intra.peff.net>
Am 11.08.23 um 20:24 schrieb Jeff King:
> On Fri, Aug 11, 2023 at 07:59:12PM +0200, René Scharfe wrote:
>
>>> 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?
>>
>> I don't see on which basis the compiler could refuse. We can't expect
>> the function address to be the same across compilation units, but we
>> don't need that. If there's a compiler that won't do it or a standards
>> verse that makes this dubious then I'd like to know very much.
>
> I seem to recall some quirks where an inline function that is not called
> directly is not required to be compiled at all, and the compiler can
> assume that there is a definition available in another translation unit.
C99 says in 6.7.4 Function specifiers: "It is unspecified whether a call
to the function uses the inline definition or the external definition.",
referring to functions with both types of definition. So a compiler
could ignore the inline version for those.
> But I think that only applies when no storage-class specifier is
> provided. In this case, you said "static", so I think it's OK?
That's how I understand it as well -- there is no external version to
choose and the compiler is not free to ignore the inline one.
> It's possible I'm mis-remembering the issues, too. One problem is that
> pre-C99, you might end up with the opposite problem (a compiled function
> with visible linkage that conflicts with other translation units at link
> time). E.g. here:
>
> https://stackoverflow.com/questions/51533082/clarification-over-internal-linkage-of-inline-functions-in-c/51533367#51533367
>
> But I think with "static" we should always be OK.
*nod*
> Don't get me wrong, I like type checking. It's just that doing weird
> things with the language and pre-processor also carries a cost,
> especially in an open source project where new folks may show up and say
> "what the hell is this macro doing?". That's a friction for new
> developers, even if they're comfortable with idiomatic C.
Sure, but that ship has sailed in this specific case. Standard option
parsing would use getopt or getopt_long, neither of which has void
pointers. We already carry the cost of our OPT_ macros. Let's ease it.
> That said...
>
>> A good example in parseopt: The patch below adds type checking to the
>> int options and yields 79 warning about incompatible pointers, because
>> enum pointers were used in integer option definitions. The storage size
>> of enums depends on the member values and the compiler; an enum could be
>> char-sized. When we access such a thing with an int pointer we write up
>> to seven bytes of garbage ... somewhere. We better fix that.
>
> ...I do find this evidence compelling.
It's 3 instead of 7 bytes of garbage, but the point still stands..
René
next prev parent reply other threads:[~2023-08-12 5:11 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
2023-08-11 17:59 ` René Scharfe
2023-08-11 18:24 ` Jeff King
2023-08-12 5:11 ` René Scharfe [this message]
2023-08-11 15:13 ` Jeff King
2023-08-11 17:59 ` René Scharfe
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