bfe6e5c418
Fix return type notation associated type suggestion when -Zlower-impl-trait-in-trait-to-assoc-ty This avoid suggesting the associated types generated for RPITITs when the one the code refers to doesn't exist and rustc looks for a suggestion. r? `@compiler-errors`
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.