Undefined symbol error at runtime

[martincpp]

I have compiled a library A with gcc 7.5 that references in a implementation file (.cpp) a class of another library B. But the referenced library B is not added as a dependency to library A.
When I compile this library A with msvc & Windows, I get no error at application runtime. When compiled with gcc under linux, there is a undefined symbol error at application runtime. Why is that? Why is the application running fine under windows, but not under linux?

[keskiverto]

Linking in Linux differs from Windows and OS X.

There is not much "linking", when you create a library. You need all the libraries when you link an executable.