[CMake] Cmake 2.8 and cross compilation

[Alexander Neundorf]

On Monday 16 November 2009, Emmanuel Blot wrote:
> > Can you create a bug entry for this?
>
> Sure,  I'll do it
>
> > As a quick fix I think if you set CMAKE_OSX_DEPLOYMENT_TARGET to empty it
> > will stop CMake form doing this.  You should be able to do that either in
> > the cache or in your project.
>
> Ok, it seems to work, thanks for the workaround.
>
> Now the actual issue, as I'm able to reproduce the original Linux host
> error: Assembly support seems broken, or at least not compatible with ATT
> mode from 2.5/2.6:
>
> Here is a CMake snippet of what we've been using up to now to build
> assembly source files:
> ENABLE_LANGUAGE (ASM-ATT OPTIONAL)
> SET (CMAKE_ASM-ATT_COMPILER ${xcc})
> SET (CMAKE_ASM-ATT_COMPILE_OBJECT
>      "<CMAKE_ASM-ATT_COMPILER> <FLAGS> -c -o <OBJECT> <SOURCE>")
> SET (CMAKE_ASM-ATT_FLAGS "${ARCH} -Wall")
> SET (CMAKE_ASM-ATT_FLAGS_DEBUG "-DDEBUG")
> SET (CMAKE_ASM-ATT_FLAGS_RELEASE "-DNDEBUG")
>
> then, to create an executable from mixed sources (.S and .c), we use
> the following syntax:
> ADD_EXECUTABLE(myapp myc.c myasm.S)

*.S (uppercase S) files are supposed to be run through the preprocessor. The 
ASM-ATT support does not involve the preprocessor, that's why *.S is not 
anymore considered to be an ASM-ATT file.
So, you can rename it to foo.s (lowercase s), then it will be processed by 
ASM-ATT, but without preprocessing.
Or you can set the LANGUAGE source file property to ASM-ATT, then it should 
also work.
If the file needs to be preprocessed, set the LANGUAGE source file property to 
C, this should work in most cases for now.

Alex