From: NRK <nrk@disroot.org>
To: musl@lists.openwall.com
Subject: Re: [musl] [C23 const 1/2] C23: change bsearch to a macro that respects the const contract
Date: Fri, 26 May 2023 23:20:37 +0600 [thread overview]
Message-ID: <20230526172037.o2l4y63edb3k2n3n@gen2.localdomain> (raw)
In-Reply-To: <3a4f4a8e-9179-6606-e449-6fc2812d3525@mulle-kybernetik.com>
On Fri, May 26, 2023 at 01:29:31PM +0200, Nat! wrote:
> I think it's sort of obvious, that these macros increase code brittleness
> due to now multiple execution of macro arguments vs. a single execution in a
> function call.
It would be heavily surprising if the controlling expression of _Generic
was evaluated. Similar to `sizeof`, it only needs to know the type of
the expression and thus doesn't require evaluation (only exception being
VLAs in a sizeof).
And looking at cppreference, it seems that the controlling expression
indeed isn't evaluated: https://en.cppreference.com/w/c/language/generic#Notes
| The controlling-expression and the expressions of the selections that
| are not chosen are never evaluated.
However, there is one thing that I don't quite understand about this
patch:
> + void const*: (void const*)bsearch((K), (void const*)(B), (N), (S), (C)), \
What's with the `(void const*)(B)` cast? It's already determined to be
`void const *` via _Generic.
- NRK
next prev parent reply other threads:[~2023-05-26 17:21 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-25 14:44 [musl] [C23 const 0/2] some interfaces become type-generic Jens Gustedt
2023-05-25 14:44 ` [musl] [C23 const 1/2] C23: change bsearch to a macro that respects the const contract Jens Gustedt
2023-05-26 11:29 ` Nat!
2023-05-26 17:20 ` NRK [this message]
2023-05-26 19:29 ` Jₑₙₛ Gustedt
2023-05-26 20:09 ` Rich Felker
2023-05-27 7:51 ` Jₑₙₛ Gustedt
2023-05-25 14:45 ` [musl] [C23 const 2/2] C23: change string.h and wchar.h interfaces to macros " Jens Gustedt
[not found] <cover.1685541439.git.Jens.Gustedt@inria.fr>
2023-05-31 14:00 ` [musl] [C23 const 1/2] C23: change bsearch to a macro " Jens Gustedt
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