http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48406
Summary: <algorithm> #undefs isfinite() from math.h in C++0x
mode
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: jyass...@gcc.gnu.org
$ cat test.cc
#include <math.h>
#include <algorithm>
bool foo(double d) {
return isfinite(d);
}
$ ~/opensource/gcc/git/install/bin/g++ -c test.cc
$ ~/opensource/gcc/git/install/bin/g++ -c test.cc -std=gnu++0x
test.cc: In function ‘bool foo(double)’:
test.cc:5:20: error: ‘isfinite’ was not declared in this scope
test.cc:5:20: note: suggested alternative:
.../include/c++/4.7.0/cmath:528:21: note: ‘std::isfinite’
$
This is a regression since gcc-4.4:
$ g++-4.4 -c test.cc -std=gnu++0x
$
It happens because <stl_algo.h> includes <random> in C++0x mode only, and
<random> includes <cmath>, which #undefs all the C99 math functions that
<math.h> defined, without 'using' the std functions back into the global
namespace.
As far as I can tell, [depr.c.headers] says that <math.h> puts the <cmath>
names into the global namespace, and it doesn't allow a later include of
<cmath> to take them back out. [depr.c.headers] also allows <cmath> to
unconditionally put its declarations and definitions into the global namespace,
which is what I'd propose as a fix.
