I did a checkout of master branch of swift repo the proceeded to check dependencies:
and compilation would break with following error:
and then :
Okay. Can one of you file a bug? And then the workaround I'd suggest would be deleting the CMakeCache.txt files out of your build directory, and then running build-script again with the DEVELOPER_DIR environment variable set to /Applications/Xcode.app (or wherever your Xcode 10.1 lives).
before re-running build script would as well fix the issue.