[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.