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.
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