[CMake] CMAKE_OSX_ARCHITECTURES and 4-way universal binaries

[Michael Jackson]

On Dec 8, 2008, at 8:28 PM, Sean McBride wrote:

> Hi all,
>
> With 2.6.2, when I do 'C'onfigure, CMake gives me:
>
> CMake Error at /Applications/CMake 2.6-2.app/Contents/share/cmake-2.6/
> Modules/CheckTypeSize.cmake:89 (MESSAGE):
>   CHECK_TYPE_SIZE found different results, consider setting
>   CMAKE_OSX_ARCHITECTURES or CMAKE_TRY_COMPILE_OSX_ARCHITECTURES to  
> one or no
>   architecture !
> Call Stack (most recent call first):
>   Utilities/kwsys/CMakeLists.txt:456 (CHECK_TYPE_SIZE)
>
> If I ignore it, things seem to be OK, but this has been bugging me  
> for a
> while now.
>
> After conferring with Mike Jackson, it turns out that if I change  
> what I had:
>
> SET (CMAKE_OSX_ARCHITECTURES "ppc;ppc64;i386;x86_64" CACHE STRING  
> "Rogue")
>
> to
>
> SET (CMAKE_OSX_ARCHITECTURES "ppc;i386;x86_64;ppc64;" CACHE STRING  
> "Rogue")
>
> the error goes away.  It surprises me that the order should be  
> important.
>
> I know what CMAKE_OSX_ARCHITECTURES is, but what is
> CMAKE_TRY_COMPILE_OSX_ARCHITECTURES?
>
> What's going on?
>
> Thanks,
>
> -- 
> ____________________________________________________________
> Sean McBride, B. Eng                 sean at rogue-research.com
> Rogue Research                        www.rogue-research.com
> Mac Software Developer              Montréal, Québec, Canada


Just to add some more background I traced the error down to the  
Modules/CheckTypeSize.cmake file. At line 77 in that file there is a  
check for a certain string within the binary file that gets compiled.

FILE(STRINGS "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/ 
CheckTypeSize.bin"
         CMAKE_CHECKTYPESIZE_STRINGS LIMIT_COUNT 2 REGEX "INFO:sizeof")

I did a quick test on some of my own cmake code where I also do a  
bunch of checks. One of those checks is the sizeof(ssize_t). When that  
test is executed I get the following for the  
CMAKE_CHECKTYPESIZE_STRINGS variable:

INFO:sizeof[00004]; INFO:sizeof[00008]

when I invoke cmake with the following:  
DCMAKE_OSX_ARCHITECTURES:string='ppc;ppc64;i386;x86_64'

If I switch it around like Sean now has it I get:
-- Check size of size_t
-- CMAKE_CHECKTYPESIZE_STRINGS:  INFO:sizeof[00004];INFO:sizeof[00004]

Which all kinda makes sense once I understood what the  
FILE(STRINGS .. ) command was using for variables. But what is the  
point of the code? I am not sure what sense it makes to run a  
CheckTypeSize(ssize_t) on a binary that has 2 different address  
models. I tried to work through some code to figure out the  
ramifications but it is kinda late..


_________________________________________________________
Mike Jackson                  mike.jackson at bluequartz.net
BlueQuartz Software                    www.bluequartz.net
Principal Software Engineer                  Dayton, Ohio