When an inline function is marked __declspec(dllimport), the function definition in this compilation unit might be inlined, but is never generated out-of-line. An out-of-line call or address reference uses the imported symbol.
You can only use __declspec(dllimport) on extern functions and variables, and on classes.
When a class is marked __declspec(dllimport), its static data members and member functions are all imported. When individual static data members and member functions are marked with __declspec(dllimport), only those members are imported.