Deep secret of CMake: it's a line by line interpreter, so you could have worked around the toolchain issue by setting the relevant variable as one of the first

Deep secret of CMake: it's a line by line interpreter, so you could have worked around the toolchain issue by setting the relevant variable as one of the first line in the project. However, you're supposed to set the toolchain on the command line and toolchain files are only intended to specify what's necessary for the toolchain. Setting defaults is considered a bad thing.