Starting with Xcode 8 the SDK folder also contains an unversioned
entry:
$ ls -l /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs
drwxr-xr-x 5 root wheel 170 Mar 4 2018 MacOSX.sdk
lrwxr-xr-x 1 root wheel 10 Sep 16 20:49 MacOSX10.12.sdk -> MacOSX.sdk
If this unversioned path is used CMake cannot detect the SDK
version. To work around the problem we always invoke the code path
that translates short SDK names like "macosx10.12" into a path.
That way we always end up with a versioned SDK path in
_CMAKE_OSX_SYSROOT_PATH which is later used to determine the version.
Closes: #16323
OS X supports using the SDK for any version equal to or newer than
the deployment target. There is no reason to warn if the versions
do not match exactly.
Suggested-by: James Burgess <jamesrburgess@mac.com>
Suggested-by: Clinton Stimpson <clinton@elemtech.com>
If the automatically selected SDK is newer than the host OS version
and no deployment version has been set then adjust the deployment
version to the host OS version. Otherwise the user won't be able to
launch the executables on the build host.
This is for example a problem on a MacOSX 10.10 host with Xcode 7
which only provides a MacOSX10.11 SDK.
For example if one installs Xcode 4.6 on OS X 10.9, it doesn't contain
a 10.9 SDK, so fallback to the next newest version which, in this case,
happens to be a 10.8 SDK.
This fixes bug #14572.
Initialize variables CMAKE_OSX_SYSROOT, CMAKE_OSX_DEPLOYMENT_TARGET, and
CMAKE_OSX_ARCHITECTURES prior to enabling any languages. This will
allow compiler identification to consider these values.
Gregor Jasny
Brad King
Clinton Stimpson