[CMake] Proper way to support 64bit and 32bit builds

[J Decker]

I would think the find is using something like...  so you'll need to adjust
cmake_sizeof_void_p

if( CMAKE_SIZEOF_VOID_P EQUAL 8 )
    DEFINE_DEFAULT( __64__ ON )
else( CMAKE_SIZEOF_VOID_P EQUAL 8 )
    DEFINE_DEFAULT( __64__ OFF )
endif( CMAKE_SIZEOF_VOID_P EQUAL 8 )
SET( __64__ ${__64__} CACHE BOOL "Enable 64 considerations" )


On Sat, Oct 29, 2016 at 3:22 AM, cen <imbacen at gmail.com> wrote:

> Hi
>
> Once I switch to 32bit builds, CMake fails to recognise that
> glibc-devel.i686 is not installed resulting in an error when running make.
> In the same way, my own FindGMP fails to recognize that gmp-devel.i686 is
> not installed. I need CMake to fail if these things are missing.
> At least for the compiler part, I'm pretty sure I am missing some var or
> flag to tell CMake I expect a 32 bit build.
>
> This is what I use to switch between builds in CMakeLists.txt (ARCH var is
> irrelevant here,  I use it later on for CPack):
>
> if (BUILD_32)
>         set_target_properties(${PROJECT_NAME} PROPERTIES COMPILE_FLAGS
> "-m32" LINK_FLAGS "-m32")
>         MESSAGE(STATUS "Excluding 64bit library paths from search.")
>         set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIB64_PATHS OFF)
>         set(ARCH i686)
> elseif (BUILD_64)
>         set_target_properties(${PROJECT_NAME} PROPERTIES COMPILE_FLAGS
> "-m64" LINK_FLAGS "-m64")
>         set(ARCH amd64)
> else()
>         set(ARCH amd64)
> endif()
>
>
> For the FindGMP module, I am not really sure what the best practice
> is.Does the BUILD_32 and BUILD_64 flag propagate into the FindGMP? Do I
> explicitly specify paths for 32bit libs (eg: /usr/lib64) or can  cmake be
> smarter than this?
> --
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