Earlier quoted context omitted.
rustc already requires passing an --extern flag for each 'extern crate' in the source, so in some sense, yes. You'd be passing that stuff along. You already have to know where those deps are on disk; the difference is that you wouldn't have a list of which deps in the source code. But if you did, it would work.
> rustc already requires passing an --extern flag for each 'extern crate' in the source Only if it can't find the crate otherwise. Generally it just searches your library path and any directories you specify with -L, e.g. most cargo executables can be recompiled (the first compilation via cargo used to compile the dependencies) via `rustc src/main.rs -L target/debug/deps`
(And that doesn't change the main point, which is that you could still be explicit about what deps you're including)