Warning C6387 Visual Studio

Question

What is Visual Studio trying to tell me with this warning?

According to the docs, this warning is when you're passing a potentially null value to a parameter.

But I'm checking for null with if (hwnd) before calling these functions.

if (hwnd) {
    GetClientRect(hwnd, (LPRECT)&rMyRect);
    ClientToScreen(hwnd, (LPPOINT)&rMyRect.left);
    ClientToScreen(hwnd, (LPPOINT)&rMyRect.right);
}

Answer 1

The fact that you test for it is not relevant, the compiler isn't detecting that test. You can, however, use:

#pragma warning(suppress : 6387)

on the prior line and that will prevent the message (or use __Pragma(warning(suppress : 6387)) but I prefer the #pragma form.