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Fix isinf/isnan declaration conflict with C++11

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GLIBC declares isinf and isnan as expected by Unix98 and for C99 programs
these functions are hidden by the generics inf and isnan macros.
However C++11 defines isinf and isnan with the same semantics as C99
but requires that they are functions not macros (C++11 26.8 [c.math]
paragraph 10).

This then results in a conflict for perfectly valid C++11 programs:

--
using std::isinf;
using std::isnan;

double d1 = isinf(1.0);
double d2 = isnan(1.0);

d.cc:3:12: error: ‘constexpr bool std::isinf(double)’ conflicts with a previous declaration
 using std::isinf;
[...]
/usr/include/bits/mathcalls.h:201:1: note: previous declaration ‘int isinf(double)’
 __MATHDECL_1 (int,isinf,, (_Mdouble_ __value)) __attribute__ ((__const__));
[...]
--

This patch fixes the prototypes by leaving the obsolete functions
defined for C++98 code (since they do not conflict with any standard
function in C++98), however preventing them on C++11.

No issues found in libstdc++ tests and check on x86_64 and i686 with
glibc testsuite.

Patch from Jonathan Wakely  <jwakely.gcc@gmail.com>.

	[BZ #19439]
	* math/bits/mathcalls.h
	[!__cplusplus || __cplusplus < 201103L] (isinf): Do not declare
	prototype.
	[!__cplusplus || __cplusplus < 201103L] (isnan): Likewise.
This commit is contained in:
Adhemerval Zanella 2016-01-11 13:34:52 -02:00
parent c83196b0df
commit d9b965fa56
2 changed files with 13 additions and 0 deletions
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9
ChangeLog
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@ -1,3 +1,12 @@
2016-01-11 Jonathan Wakely <jwakely.gcc@gmail.com>
Adhemerval Zanella <adhemerval.zanella@linaro.org>
[BZ #19439]
* math/bits/mathcalls.h
[!__cplusplus || __cplusplus < 201103L] (isinf): Do not declare
prototype.
[!__cplusplus || __cplusplus < 201103L] (isnan): Likewise.
2016-01-11 Andreas Schwab <schwab@suse.de>
[BZ #19253]

4
math/bits/mathcalls.h
View File

@ -196,9 +196,11 @@ __MATHDECL_1 (int,__finite,, (_Mdouble_ __value)) __attribute__ ((__const__));
_Mdouble_END_NAMESPACE
#ifdef __USE_MISC
# if !defined __cplusplus || __cplusplus < 201103L /* Conflicts with C++11. */
/* Return 0 if VALUE is finite or NaN, +1 if it
is +Infinity, -1 if it is -Infinity. */
__MATHDECL_1 (int,isinf,, (_Mdouble_ __value)) __attribute__ ((__const__));
# endif
/* Return nonzero if VALUE is finite and not NaN. */
__MATHDECL_1 (int,finite,, (_Mdouble_ __value)) __attribute__ ((__const__));
@ -230,8 +232,10 @@ __END_NAMESPACE_C99
__MATHDECL_1 (int,__isnan,, (_Mdouble_ __value)) __attribute__ ((__const__));
#if defined __USE_MISC || (defined __USE_XOPEN && !defined __USE_XOPEN2K)
# if !defined __cplusplus || __cplusplus < 201103L /* Conflicts with C++11. */
/* Return nonzero if VALUE is not a number. */
__MATHDECL_1 (int,isnan,, (_Mdouble_ __value)) __attribute__ ((__const__));
# endif
#endif
#if defined __USE_MISC || (defined __USE_XOPEN && __MATH_DECLARING_DOUBLE)