/Wp64
/Wp64 detects 64-bit portability problems on either Win32 or Win64 platforms. Any difference in the number of portability warnings generated between Win32 and Win64 can be corrected by using the __w64 qualifier on Win32. The __w64 qualifier tells the compiler what types are defined as 64-bit on Win64.
Variables of the following types are tested on a 32-bit operating system as if they were 64 bits:
Compiler Options | Setting Compiler Options