I know the borrow checker uses rules, but I don't know enough about the internal implementation details to use fully precise terminology. I don't mean borrow checking is just a chain of if-statements or something. I meant check in the abstract.

From the GitHub thread: "I think unification just generally doesn't check lifetime bounds of the type." [0]

There are steps, or rules or whatever, that perform soundness (or well-formedness or whatever) checks. And clearly one was missing.

My guess was just that maybe someone didn't think it was necessary for soundness.

[0]: https://github.com/rust-lang/rust/issues/164250#issuecomment...