mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-23 23:34:48 +00:00
be4f9f5bec
Fix elaboration with associated type bounds When computing a trait's supertrait predicates, do not add any associated type *trait* bounds to that list of supertrait predicates. This is because supertrait predicates are expected to have the same `Self` type as the trait. For example, given: ```rust trait Foo: Bar<Assoc: Send> ``` Before, we would compute that the supertrait predicates of `T: Foo` are `T: Bar` and `<T as Bar>::Assoc: Send`. However, the last bound is a trait predicate for a totally different type than `T`, and existing code that uses supertrait bounds such as vtable construction, closure fn signature deduction, etc. all rely on the invariant that we have a list of predicates for self type `T`. Fixes #76593 The reason for all the extra diagnostic noise is that we're recomputing predicates with a different filter now. These diagnostics should be deduplicated for any end-user though. --- This does bring up an interesting question -- is the predicate `<T as Bar>::Assoc: Send` an implied bound of `T: Foo`? Because currently the only bounds implied by a (non-alias) trait are its supertraits. I guess I could fix this too, but it would require even more changes, and I'm inclined to punt this question along. |
||
|---|---|---|
| .. | ||
| src | ||
| Cargo.toml | ||
| messages.ftl | ||
| README.md | ||
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.