Idea: Enable Cargo to cache dependencies locally

[tema2]

@Mart-Bogdan

This would create security issues as other users could tamper with files

Isn't this question to machines admin?

Also, note that any user on machine can be infected by malware, in this case we also cannot protect cache anyway - separating privileges further harms usability.

@Mart-Bogdan

Actually, we can. It just would waste disk space. Cargo already creates separate folders for different configs. If you go into target dir you'll notice that to each crate build hash is added. It consists of a compiler version and build flags. So the mechanism is in place.

Thanks for the flags detail, but this way changing compiler version would require to recompile world. We might need a stable ABI, its versioning, keep track of which versions of internal representation used in incremental cache, to recompile only if necessary. This way we could keep maximum of binary artifacts from previous compilation.