g++4.9.2 fails to compile standard C++11 code

[Vlad Gheorghiu]

The following code fails to compile under latest cygwin, Windows 7,
g++4.9.2. Compiled with g++ -std=c++11 test.cpp. The compiler
complains that std::log2 is not a member of std.

    #include <cmath>
    #include <iostream>

    int main()
    {
            auto x = std::log2(10);
            std::cout << x << std::endl;
    }


Verbatim error:

    g++ -std=c++11 test.cpp
    test.cpp: In function ‘int main()’:
    test.cpp:5:11: error: ‘log2’ is not a member of ‘std’
      auto x = std::log2(10);
               ^
    test.cpp:5:11: note: suggested alternative:
    In file included from
/usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/cmath:44:0,
                     from test.cpp:1:
    /usr/include/math.h:305:15: note:   ‘log2’
     extern double log2 _PARAMS((double));

-- 
Dr. Vlad Gheorghiu
Institute for Quantum Computing
Waterloo, Ontario
Canada
http://community.iqc.uwaterloo.ca/vgheorgh/

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