We've experimented with MIR-only rlibs - https://github.com/rust-lang/rust/issues/38913#issuecomment-369584928 https://github.com/rust-lang/rust/issues/38913#is

We've experimented with MIR-only rlibs - https://github.com/rust-lang/rust/issues/38913#issuecomment-369584928 https://github.com/rust-lang/rust/issues/38913#issuecomment-... has some recent data on it - which seem to me like the best approach for solving this, but it needs more work. Eventually, we might compile everything at once, making the whole "crate" separation a tad bit obsolete (or even silly), other than for code organization (it has other complications, like trait coherence).