[batat]

I can't build it with fsanitize=undefined at all with clang 3.4:

    > clang -Os -std=c++11 -Wall -o boom -fsanitize=undefined boom.cpp 
    /tmp/boom-428713.o:(.rodata._ZTIFvvE[_ZTIFvvE]+0x0): undefined reference to `vtable for __cxxabiv1::__function_type_info'
    /tmp/boom-428713.o:(.rodata._ZTIFivE[_ZTIFivE]+0x0): undefined reference to `vtable for __cxxabiv1::__function_type_info'
    clang: error: linker command failed with exit code 1 (use -v to see invocation)