must be enabled with the -std=c++11

/usr/local/lib/gcc49/include/c++/bits/c++0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support is
currently experimental, and must be enabled with the -std=c++11 or -std=gnu++11 compiler options.

Anyone know what it wants?
Read the source code. Exactly which C++-11 features does it need? I'm going to bet that those are available in CLANG, since that also supports C++-14.