Re: 'log2' is not a member of 'std'

[Joshua Root]

This is MacOSX 10.6.8 running various compilers provided by MacPorts.
Compiling the following C++ source
        #include <cmath>

        int main(void)
        {
                double d = std::log2(2.3456789f);
                return 0;
        }

results in

        'log2' is not a member of 'std'.

This happens with the system g++, which is i686-apple-darwin10-g++-4.2.1,
each of g++-4.0 g++-4.2 g++-mp-5 g++-mp-6, and with clang++-mp-3.4;
in each case, I am compiling as $CXX -std=c++11 prog.c

Apparently, there is some relatively recent turmoil about the C++ libs;
I don't know much c++ but find myself compiling some third party C++ code.
Am I missing something obvious?

Well the Xcode-supplied g++s and clang would be using the system 
libstdc++, which doesn't support C++11, and std::log2 is a C++11 feature.

The g++-mp variants should support it, but seemingly don't because of 
the bug that Ken mentioned, which should be fixed in GCC 7.

Clang can support C++11 if you use -stdlib=libc++.

- Josh