The following program

#include <Python.h>
#include <cmath>

results in the following error when compiled with g++ and -std=gnu++0x:

$ g++ -std=gnu++0x -c t.cc -I /c/Python27/Include
In file included from c:\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.5.1/include/c++/cmath:629:0,
                 from t.cc:2:
c:\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.5.1/include/c++/tr1_impl/cmath:203:11: error: '::hypot' has not been declared

The problem is, that pyconfig.h has the following define:

#define hypot _hypot

It should probably just be removed when using gcc.