It seems Rust and D have very very similar C FFIs, see http://doc.rust-lang.org/book/ffi.html .

https://github.com/crabtw/rust-bindgen is a tool in the vein of dstep.

(Rust has the advantage of having no runtime beyond what C needs unlike D with its current garbage collector, so FFI, especially exposing a C interface, is likely somewhat simpler.)