[ori_b]

The same difficulty,more or less. Mangle in your front-end. The problem comes from the fact that half of C++ lives in headers in the form of templates, so there isn't any code to call, from the perspective of a compiler back end.

To link against code using things like the STL, your compiler would basically need to understand how to compile C++.

Same problem as macros in C, but macros are usually less pervasive in C code, meaning that often you get a good enough binding by ignoring them or filling in wrapper functions by hand.