I'm interested in getting Swift cross-compiling to arm(v7)-linux. (For my specific use case, I actually need to be able to cross-compile for arm-linux from a *Darwin* host. A little strange, I know.)
In digging through the build scripts and CMake listfiles, I discovered that cross-compilation is not supported in a way that is sufficiently generic to support my use case; it's all pretty special-cased around Darwin => iOS (or derivative) cross-compilation.
I can't imagine more than, like, three people want to do Darwin => arm-linux cross-compilation, so adding support for that specific combination upstream seems pretty useless—but if the build scripts supported cross-compilation in a fairly generic fashion, I imagine that's something that more people would be happy to see.
Given that it seems like a non-trivial amount of build script/CMake work is needed to support cross-compilation in a generic way, I'm curious if there is even a remote desire to see that land in the tree. If so, I'd be more than happy to spearhead or otherwise assist with that effort.