Is there an ABI compatibility issue if part of the code of a C project is rewritten in C++, but with the same API left out?

Question

For a shared library project written in C, if I rewrite part of the code in C++, but exactly the same APIs is kept, will I have any ABI compatibility issues?

This depends on the compiler, but at the least, you will probably need to use an [extern "C"](http://en.cppreference.com/w/cpp/language/language_linkage) specifier. — Mankarse, Jun 27 '14 at 05:16

score 4 · Accepted Answer · edited May 23 '17 at 12:11

If you keep the same API (function names and parameter types) you should be good to go.

What you will need to do is wrap your header files with this _{(copy & pasted from here)}:

#ifdef __cplusplus
extern "C" {
#endif

// all of your legacy C code here

#ifdef __cplusplus
}
#endif

This makes sure that the C++ compiler doesn't mangle those names, so the C compiler's extern symbols can still be linked against the exports.

Is there an ABI compatibility issue if part of the code of a C project is rewritten in C++, but with the same API left out?

1 Answers1