From: Paul Eggert <eggert@cs.ucla.edu>
To: Collin Funk <collin.funk1@gmail.com>
Cc: "bug-gnulib@gnu.org" <bug-gnulib@gnu.org>
Subject: Re: byteswap.h behavior
Date: Sun, 12 May 2024 13:30:50 -0700 [thread overview]
Message-ID: <46573ff0-0cd7-4d96-9f41-ec6c8a94ed89@cs.ucla.edu> (raw)
In-Reply-To: <bf40370e-abe5-4eb3-a6e6-dbfeaca7ad34@gmail.com>
On 2024-05-12 12:47, Collin Funk wrote:
> Yeah, I read the POSIX draft and it says that they may be macros. I
> doubt the byteswap.h and endian.h functions are used with non-constant
> expression arguments that often.
I sense a bit of confusion here. Although POSIX allows <endian.h>
symbols like be16toh to be macros, I don't see where it allows
be16toh(X) to evaluate X more than once, so an expression like
be16toh(i++) has well-defined behavior even though it has a side effect.
A few function-like macros, like getc, are explicitly allowed to
evaluate their arguments more than once, but ordinarily function-like
macros are supposed to act like their corresponding functions.
next prev parent reply other threads:[~2024-05-12 20:31 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-12 19:23 byteswap.h behavior Collin Funk
2024-05-12 19:38 ` Paul Eggert
2024-05-12 19:47 ` Collin Funk
2024-05-12 20:02 ` Bruno Haible
2024-05-12 20:11 ` Collin Funk
2024-05-12 20:30 ` Paul Eggert [this message]
2024-05-12 22:43 ` Collin Funk
2024-05-12 23:10 ` endian.h Bruno Haible
2024-05-12 19:50 ` byteswap.h behavior Jeffrey Walton
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