[steveklabnik]

There's significant difference between the edition system and the C and C++ standards, and that is that the standards are done when they're done, but the editions are not, exactly. That is, new features arrive in the largest set of editions possible, whereas C99 is frozen in time. This is not to say that you or the parent are wrong exactly, but it doesn't really work in exactly the same way.

[pjmlp]

I still look forward to how editions will actually work in practice, when Rust gets a couple of years behind it.

Lib A compiled with edition 2018, talking callbacks to functions implemented in Lib B with edition 2020, Lib C edition 2030 importing Lib D edition 2025.

Naturally, I am also assuming that for pleasing the commercial users of binary libraries, typical in C and C++ universe, all those crates are only available as binary libraries being pulled into a multi-edition final executable.

[dralley]

Rust does not yet have a stable ABI, and there is not any such thing as a "binary crate" at the moment. So it's kind of hard to run into that problem as the entire exercise is impossible.

[pjmlp]

That exercise is possible to some extent with C and C++, so the whole point is to prove that epochs aren't the gold solution over language selection switches, as they are currently sold.