How to detect if 64 bit MSVC with cmake?

Question

I have a project which uses cmake, one target is set to only build with MSVC:

 if (MSVC)
     add_library(test SHARED source.cpp) 
 endif()

Answer 1

The usual way to check if you're generating for a 64 bits architecture is to test CMAKE_SIZEOF_VOID_P:

if(CMAKE_SIZEOF_VOID_P EQUAL 8)
    # 64 bits
elseif(CMAKE_SIZEOF_VOID_P EQUAL 4)
    # 32 bits
endif()