[CMake] Linking against OS X Frameworks

[Mike Jackson]

On Sun, Aug 9, 2009 at 3:07 PM, Michael Wild<themiwi at gmail.com> wrote:
>
> On 9. Aug, 2009, at 18:59, ML wrote:
>
>> Michael,
>>
>> Thank you for this example! It was really informative. Definitely a
>> missing piece in my knowledge thus far.
>>
>> One question:
>>
>> I get an error stating:
>>
>> CMake Error at CMakeLists.txt:70 (message):
>>  MoreFilesX requires the SDK version to be not newer than 10.4u (10.6
>>  detected)
>>
>> this comes from here:
>>
>>> # figure out Mac OSX SDK version (do not care for the u-suffix in 10.4u)
>>> get_filename_component( SDK_VER ${CMAKE_OSX_SYSROOT} NAME )
>>> string( REPLACE ".sdk" "" SDK_VER ${SDK_VER} )
>>> string( REPLACE "MacOSX" "" SDK_VER ${SDK_VER} )
>>> string( REGEX REPLACE "[a-zA-Z]" "" SDK_VER ${SDK_VER} )
>>> # this REALLY needs the 10.4 SDK.
>>> if( ${SDK_VER} VERSION_GREATER 10.4 )
>>> message( SEND_ERROR "MoreFilesX requires the SDK version to be not newer
>>> than 10.4u (${SDK_VER} detected)" )
>>> endif( ${SDK_VER} VERSION_GREATER 10.4 )
>>
>> So how do I turn around and set 10.4u if it is not automatically detected?
>>
>> It is like this:
>>
>> CMAKE_OSX_SYSROOT=/Developer/SDKs/MacOSX10.4u.sdk
>>
>> Best,
>>
>> -Jason
>>
>
> CMake by default detects the most current SDK. If you want to use a
> different one, you have to set it in the cache, by e.g. executing
>
> cmake -DCMAKE_OSX_SYSROOT=/Developer/SDKs/MacOSX10.4u.sdk
> -DCMAKE_OSX_DEPLOYMENT_TARGET=10.4 .
>
> in the build tree. Above command also sets CMAKE_OSX_DEPLOYMENT_TARGET=10.4
> for consistency.
>
> Please note that it is supported (and meaningful) to have different versions
> of the SDK and the deployment target (both of them may be newer than the
> other, so "all combinations allowed"). However, this has implications on
> compiling, linking and loading, which I can't remember just off the top of
> my head.
>
> Michael

the CMAKE_OSX_DEPLOYMENT_TARGET setting controls the "Weak Linking"
that OS  X does. It basically says what the minimum version of OS X
your program can run on.


the CMAKE_OSX_SYSROOT setting controls the "maximum" version of OS X
that your program can run on. By setting BOTH to 10.4 you are
basically saying that your program can run ONLY on OS X 10.4. Is that
what you want?

If you link against a library that has a function in 10.5 that is not
in 10.4 then your program will likely crash. It is up to you to take
the necessary steps in your code to ensure this does not happen, maybe
by using an alternate function?

If you read bug number 6195 you will get all the detailed explanations
you need plus all the history that will allow you to make an informed
decision about how to set those values:

http://public.kitware.com/Bug/view.php?id=6195

Mike