[SOLVED] Platform detection in CMake

Issue

I've added some functionality from boost::asio, which has precipitated some compiler "warnings":

Please define _WIN32_WINNT or _WIN32_WINDOWS appropriately.

That problem was dealt with here. I'd like to have CMake detect when I am building on Windows and make the appropriate definitions or command line arguments.

Solution

Here is a simple solution.

macro(get_WIN32_WINNT version)
    if (WIN32 AND CMAKE_SYSTEM_VERSION)
        set(ver ${CMAKE_SYSTEM_VERSION})
        string(REPLACE "." "" ver ${ver})
        string(REGEX REPLACE "([0-9])" "0\\1" ver ${ver})

        set(${version} "0x${ver}")
    endif()
endmacro()

get_WIN32_WINNT(ver)
add_definitions(-D_WIN32_WINNT=${ver})

Answered By - KneLL