[CMake] Triggers for isysroot

[P. Martin]

On Mar 11, 2012, Michael Wild <themiwi at gmail.com> wrote: 
> 
> I think it depends on what you set it to. If it's the default SDK, it
> doesn't get included. It could also be that the
> CMAKE_OSX_DEPLOYMENT_TARGET variable plays into this.
> 
> Sadly, my Mac died quiet some time ago, so I can't check right now...
> 
> Michael


Thank you for the reply.  I'm off to wipe and reinstall because there
have been three xcodes and three os versions in as many months.
I have to get a baseline.

But on this topic, I'm hypothesizing that there are well defined cases,
when compiling for one architecture, that the sysroot path will get added.

I think the sysroot path is attached somehow to -arch x86_64, but I'm
just not up to reading the source today.  I was hoping this would be an
easy answer.  The failure I'm trying to simplify to a reproducible case
has only two CXX_FLAGS out of twenty that I can't locate their origin.

  -arch x86_64 -isysroot /some/path/to/an/sdk

In the failing software, there is no CMAKE_OSX_DEPLOYMENT_TARGET
specified to be used or set in the command, but I will look harder in case
I missed it.  Thanks for your suggestion.