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Do not use const attribute for nan functions (bug 23277).

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As in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86113 for
__builtin_nan, bits/mathcalls.h wrongly declares the nan function with
the __const__ attribute.  Because the function reads memory pointed to
by an argument, it's only pure, not const.  This patch removes the
incorrect attribute and adds a testcase for the bug.  No __pure__
attribute is added to replace the incorrect __const__ one, since that
would introduce problems when using GCC versions that have the
incorrect built-in __const__ attribute and warn for the combination of
those two attributes.

Tested for x86_64.

	[BZ #23277]
	* math/bits/mathcalls.h [__USE_ISOC99] (nan): Do not use __const__
	attribute.
	* math/test-nan-const.c: New file.
	* math/Makefile (tests): Add test-nan-const.
	(CFLAGS-test-nan-const.c): New variable.
This commit is contained in:
Joseph Myers
2018-06-12 16:57:26 +00:00
parent cb8f6affed
commit 48b12ed54c
4 changed files with 45 additions and 2 deletions
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32
math/test-nan-const.c Normal file
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/* Test nan functions do not have const attribute. Bug 23277.
Copyright (C) 2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <math.h>
#include <string.h>
static int
do_test (void)
{
char buf[2] = { '2', 0 };
float a = nanf (buf);
buf[0] = '3';
float b = nanf (buf);
return memcmp (&a, &b, sizeof (float)) == 0;
}
#include <support/test-driver.c>