From: Joseph Myers <joseph@codesourcery.com>
To: Alejandro Colomar <colomar.6.4.3@gmail.com>
Cc: Jonathan Wakely <jwakely.gcc@gmail.com>,
"gcc@gcc.gnu.org" <gcc@gcc.gnu.org>,
linux-man <linux-man@vger.kernel.org>,
"Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Subject: Re: [RFC] man7/system_data_types.7: Document [unsigned] __int128
Date: Thu, 1 Oct 2020 17:31:26 +0000 [thread overview]
Message-ID: <alpine.DEB.2.21.2010011724580.4323@digraph.polyomino.org.uk> (raw)
In-Reply-To: <5ed7272e-1c81-d1f5-6a54-0fee4270199e@gmail.com>
On Thu, 1 Oct 2020, Alejandro Colomar via Gcc wrote:
> Because 'intmax_t' has a bug
> (actually I know GCC rejected the bug report,
> but the problem is still there and users should be informed about this)
> which is related to __int128.
__int128 is not an integer type as defined by any existing version of ISO
C, precisely because it's wider than intmax_t, and changing intmax_t would
be a big ABI problem (involving new symbol versions for about 100
printf/scanf-related functions in glibc, 200 on platforms with multiple
long double variants).
See the proposed removal of intmax_t in C2x (accepted in principle at the
first virtual Freiburg meeting, but so far without any wording accepted
for any specific approach to removal regarding e.g. preprocessor
arithmetic and other places depending on intmax_t). That removal would
allow __int128 to be considered an extended integer type as defined by C2x
and later (with int128_t typedef in <stdint.h>, etc.), if desired.
--
Joseph S. Myers
joseph@codesourcery.com
next prev parent reply other threads:[~2020-10-01 17:31 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 9:24 [RFC] man7/system_data_types.7: Document [unsigned] __int128 Alejandro Colomar
2020-10-01 9:57 ` Jonathan Wakely
2020-10-01 10:14 ` Alejandro Colomar
2020-10-01 10:50 ` Jonathan Wakely
2020-10-01 11:24 ` Alejandro Colomar
2020-10-01 11:46 ` Jonathan Wakely
2020-10-01 12:54 ` Szabolcs Nagy
2020-10-01 13:22 ` Alejandro Colomar
2020-10-01 13:46 ` Jonathan Wakely
2020-10-01 17:31 ` Joseph Myers [this message]
2020-10-02 8:10 ` Alejandro Colomar
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