Veracrypt for build under GCC6 required using compatibility flag `-std=c++98` against change default C++ frontend in GCC6. The C++ frontend now defaults to C++14 standard instead of C++98 it has been defaulting to previously, for compiling older C++ code that might require either explicitly compiling with selected older C++ standards, or might require some code adjustment, see http://gcc.gnu.org/gcc-6/porting_to.html for details. The experimental C++17 support has been enhanced in this release. from: https://gcc.gnu.org/ml/gcc-announce/2016/msg00000.html