Comment by pornel

Meaning of this code has not changed since Rust 1.0. It wasn't a language change, nor even anything in the standard library. It's just a hack that the poster wanted to work, and realized it won't work (it never worked).

This is equivalent of a C user saying "I'm disappointed that replacing a function with a macro is a breaking change".

Rust had actual changes that broke people's code. For example, any ambiguity in type inference is deliberately an error, because Rust doesn't want to silently change meaning of users' code. At the same time, Rust doesn't promise it won't ever create a type inference ambiguity, because it would make any changes to traits in the standard library almost impossible. It's a problem that happens rarely in practice, can be reliably detected, and is easy to fix when it happens, so Rust chose to exclude it from the stability promise. They've usually handled it well, except recently miscalculated "only one package needed to change code, and they've already released a fix", but forgot to give users enough time to update the package first.