LLVM += new architecture

> "All your libc headers" are not all architecture-specific, are they? Can you elaborate?

For a given OS, not all headers are arch-specific, but a large part of them is. Think about dirent structure, poll structure, fenv details, pthread structures, signal structures, stat structures, time structures, etc. ad nauseam.

And for a different OS, it's basically all the headers that need to be ported. Making basic free software libraries depend on rust basically means excluding from the free software game any non-Linux OS unless somebody takes up the daunting task of explaining the libc headers to Rust, while Rust could simply act like all other such languages (perl, python, haskell) do: just interpret the libc headers at configure time.