Getting CMake to give an error/warning about unreferenced symbols -

i'm wondering how go making cmake produce error, or @ least warning, when linker cannot find symbols referenced in source file?

for example, let's have foo.c:

#include "bar.h" //bar.h provides bar()  void foo(void) {   bar()   return; } 

in case building static library, if not smart how have used add_library() directive, default behavior seems to not give warning bar unreferenced symbols in foo's object archive file (.a)

there's -z now gcc linker these days, yeah, isn't cmake's problem.

the fool-proof way i've found works on shared libraries, write test each shared library , dlopen(path, rtld_now) (and similar windows) , use return value test return value. list of shared objects, have wrapper function around add_library adds shared libraries global property used generate tests dynamically. remember there being way tell if target shared or static, i'm not finding docs right now.