[SAHChandler]

Author of the post here.

The compiler version thing is definitely an issue. That said, if you're worried about having to litter `if/endif` calls all over the place, I recommend you look into CMake's generator expressions.

relative rpath support was added very recently and will be in the CMake 3.14 release. It's a shame it took this long to make it in.

third party libraries can be imported via add_library, and then setting the imported location. This allows, I should note, the ability to link against both static and dynamic libraries.

IXM is being developed to make it easier to do the layout system as well as make the 80% you've mentioned here basically a non-issue, and comes with a fairly decent (in my opinion) default layout. Because it's not even in an alpha state I've not had time to document it.

(Also, I am working on a build system replacement for CMake, which includes a compiler frontend translator so you can solve the cross platform compiler flag issue. CMake is simply being used to "brute"strap the project until it is self hosting)