Rust's compiler is very good at removing most unused code. You are however going to pay a lot for the compilation. In case of some of those common dependencies you are not infrequently ending up with them multiple times in your dependency tree since not all libraries move up to the latest version. For instance today I have three different versions of windows-sys in my dependency tree and three zerocopy versions.
Do you happen to also know if there is any ongoing work in rustc to make compilation faster for this situation?
I’m imagining that one could typecheck and then see if ASTs are used / unused and eliminate them before generating code. Maybe that would speed up compilation? Perhaps this is already being done.
Rust's compilation unit is an entire crate. There is not much that can be done here as far as I can tell without changing the compilation model. It's not like C++ where you can just compile individual object files. You really are hoping that the linker cleans it up.
