You haven't said what development environment/compiler you're using, but it's pretty obvious that either it's only a C and not a C++ compiler, or it does both but doesn't know that you're giving it C++ source. I use the GNU compilers, standalone without an integrated development environment, and for that you'd need to invoke arm-none-eabi-g++ instead of arm-none-eabi-gcc (assuming because you're here that you're compiling for ARM chips) but I'm guessing that information isn't going to help you much.
