[CMake] linking a C application with a C++ library

[René J.V. Bertin]

Hello,

I'm trying to write a cmake file for an older project of mine, which consists of a library (mostly C++) and a few test cases one of which is a C programme to test the library's functionality exported to C. I'd like to use a single cmake file, but am getting link error on the C app, most likely because it should be linked by the C++ linker (or at least with -X c++).

How do I instruct cmake to do this?

Thanks,
R.