Splitting implementation and interface in C++

The default for cargo install is to ignore the lock file:
https://doc.rust-lang.org/cargo/commands/cargo-install.ht...

There's no need to use a lock file or to use an online crates forge.
You can just use what is --offline available in your distribution.

I don't really get it why this would be a nontrivial task.

>I dislike just ignoring the

Well, you can either use it or ignore it.
If you don't want to use it, because you want to use your own packaged dependencies there's only the option to ignore it, right?