[CMake] CMake and OS X compiler tools without SDK

[Brad King]

On 09/20/2012 06:28 PM, Sean McBride wrote:
> On Thu, 20 Sep 2012 16:16:19 -0600, David Gobbi said:
> 
>>> You sure?  I'm pretty sure the 4.4 command line tools didn't need
>> Xcode.app either.
>>
>> Could be.  I'm still using XCode 3.2 on my own box.  It's the people
>> working under me who are using newer versions.
> 
> Ahhhh! :)  I think it's been this way since even before 4.4 actually.
> 
>> This is with cmake 2.8.9, so the latest version.  What do you mean by ToT?
> 
> Top of Tree.  As in: newest from source control.
> 
>> It could very well be that the person that I was helping with
>> this problem set some variables when I was elsewhere...
> 
> Could be, but there was some Xcode related issue I had just recently
> that's still in 2.8.9 but fixed in ToT/2.8.10.

I just made a few more commits to address this before 2.8.10.
The main changes are:

 http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=a0a0877a
 http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=230ea218

Now CMake will always verify that the SDKs directory exists
before using it.  If not it will fall back to an empty value
for CMAKE_OSX_SYSROOT.  This allows me to build with just the
command line tools for Xcode 4.5 but not the IDE.

Furthermore when CMAKE_OSX_SYSROOT is not empty then CMake
will always use the -isysroot flag if the compiler supports it.
I can now build with Xcode 4.4 without the command-line tools,
even using the Makefile generator, by setting my env with just:

 export PATH="$(dirname $(xcrun --find make)):$PATH"
 export CC="$(xcrun --find cc)"
 export CXX="$(xcrun --find c++)"

-Brad