U++

c:\u\upp16\uppsrc\Core\Callback.h: In instantiation of 'Res Upp::Function<Res(ArgTypes ...)>::Wrapper<F>::Execute(ArgTypes ...) [with F = bool; Res = bool; ArgTypes = {long long int, long long int}]':
c:\u\upp16\uppsrc\Core\Win32Util.cpp:235:1: required from here
c:\u\upp16\uppsrc\Core\Callback.h:21:60: error: expression cannot be used as a function
virtual Res Execute(ArgTypes... args) { return fn(args...); }