Inconsistent annotation for 'WinMain'

Question

I'm trying to get my code as perfect as possible, and I've cleaned up all errors and (other) warnings. I'm left with these two:

Warning C28253  Inconsistent annotation for 'WinMain': _Param_(2) has 'SAL_null(__no)' on this instance.
Warning C28252  Inconsistent annotation for 'WinMain': _Param_(2) has 'SAL_null(__maybe)' on the prior instance.

Here is my WinMain function

int CALLBACK WinMain( _In_ HINSTANCE hInstance, _In_ HINSTANCE hPrevInstance, _In_ LPSTR lpCmdLine, _In_ int nCmdShow );

Why is my second paramater HINSTANCE hPrevInstance not annotated correctly despite it being ripped straight from MSDN with the _In_ info?

Answer 1

It is because the hPrevInstance argument actually has the _In_opt_ annotation rather than just _In_.