From: Stephan Bergmann <sbergman@redhat.com>
To: libc-help@sourceware.org
Subject: math_errhandling getting undef'ed for -std=gnu11?
Date: Wed, 30 Jan 2019 09:18:00 -0000 [thread overview]
Message-ID: <fae92d8e-db57-5990-8a7d-b2149c8efc5e@redhat.com> (raw)
My understanding is that C11 requires <math.h> to define
math_errhandling (as macro or identifier with external linkage), and my
assumption is that GCC's -std=gnu11 (vs. -std=c11), while it might
enable language extensions, would not remove from that.
However, at least with glibc-headers-2.28-26.fc29.x86_64,
> $ cat test.c
> #include <math.h>
> int main() { return math_errhandling; }
fails for
> $ gcc -m32 -O -std=gnu11 test.c
> test.c: In function âmainâ:
> test.c:2:21: error: âmath_errhandlingâ undeclared (first use in this function)
> int main() { return math_errhandling; }
> ^~~~~~~~~~~~~~~~
> test.c:2:21: note: each undeclared identifier is reported only once for each function it appears in
while it succeeds for
> $ gcc -m32 -O -std=c11 test.c
What causes the difference is apparently the block
> /* Disable x87 inlines when -fpmath=sse is passed and also when we're building
> on x86_64. Older gcc (gcc-3.2 for example) does not define __SSE2_MATH__
> for x86_64. */
> #if !defined __SSE2_MATH__ && !defined __x86_64__
> # if ((!defined __NO_MATH_INLINES || defined __LIBC_INTERNAL_MATH_INLINES) \
> && defined __OPTIMIZE__)
>
> /* The inline functions do not set errno or raise necessarily the
> correct exceptions. */
> # undef math_errhandling
[...]
in /usr/include/bits/mathinline.h.
Now, my question is whether that is by design (implying that -std=gnu11
is deliberately non-conforming here) or by accident.
(But seeing
<https://sourceware.org/git/?p=glibc.git;a=commit;h=da75c1b180f9355a8b2b2584ecf1fcfe03f7107e>
"Remove x86 mathinline.h" completely dropping
sysdeps/x86/fpu/bits/mathinline.h from later glibc probably makes the
question somewhat moot.)
next reply other threads:[~2019-01-30 9:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-30 9:18 Stephan Bergmann [this message]
2019-01-30 16:30 ` Carlos O'Donell
2019-01-30 16:41 ` Joseph Myers
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=fae92d8e-db57-5990-8a7d-b2149c8efc5e@redhat.com \
--to=sbergman@redhat.com \
--cc=libc-help@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).