Hello fellow developers,
Thanks to help from @Michael_Gottesman and @millenomi, Foundation (and CoreFoundation) are now ported to CMake and the build bots are officially using the CMake based build system for the builds! This now brings nearly the entire suite of support libraries into the CMake fold, giving a roughly consistent build throughout the project (llvm, clang, cmark, swift, libdispatch, foundation, xctest are all using CMake now). It also enables cross-compilation and makes it easier to port to other targets.
This should be mostly transparent to most people, but is still a definitely improvement in the work to maintain the project.
One of the interesting bits from this work was the fallout where during the conversion it became apparent that we were building XCTest in a particular configuration but testing it completely differently due to the complexity in build-script-impl. Hopefully it will be possible to remove some of the complexity there now that we can build everything in a similar fashion.