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

[Csaba Raduly]

Hi

On Thu, Mar 12, 2015 at 10:55 AM, Duncan Roe  wrote:
> On Wed, Mar 11, 2015 at 06:55:16PM -0400, Vlad Gheorghiu wrote:
>> 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));
>>
> FWIW, this program works fine under Linux / gcc4.8.2:

ISTR a discussion about some C++11 features being configured away due
to Cygwin's lack of some C library functions ("to_string not a member
of std"): https://sourceware.org/ml/cygwin/2015-01/msg00245.html

Your issue may be related (I'm guessing here because I don't have
Cygwin at hand right now).

Csaba
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