c and c++ linkage with libraries

Question

Suppose I have a C++ library lib.h that uses classes and templates. Suppose also that I have a custom C++ header myLink.h with the following:

#include "lib.h"

  //call methods from lib.h that use templates and classes
  //  and return an integer based off of the information gained from calling functions lib.h  
  extern "C" int foo(int param1, const int param2);

Now suppose I am in a C file called test.c. Is it legal to call function foo() as follows?

//in test.c
int first = foo(5, 6);

Also, what is going on at the object code / linker phase of compilation?

Thanks!

Answer 1

Is it legal to call function foo() as follows?

 int first = foo(5, 6);

Yes, it's legal. Although you should read below to make sure this legal call will link.

what is going on at the object code / linker phase of compilation?

The use of classes won't interfere. C++ classes will be compiled to object code that the linker will understand.

Edit from Chris Dodd's comment:

Your templates will also be created by virtue of foo calling them.