print backtrace at runtime

backtrace.cpp

// #include <execinfo.h>
void * trace[128];
int const num_trace = backtrace(trace, 128);
char ** trace_symbols = backtrace_symbols(trace, num_trace);
for (int i = 0; i < num_trace; ++i) {
    std::cout << trace_symbols[i] << std::endl;
}
free(trace_symbols);