Previously, rust-analyzer would include impl methods from `impl Foo for NoSuchType`, which would lead to rust-analyzer reporting nonexistent type errors. This is noticeable when depending on tokio with feature="fs" and cfg(test) enabled. The following code would produce a type error, because Read::take() requires an argument and rust-analyzer was including Read on Option via an error type. use std::io::Read; fn f<T>(mut o: Option<T>) { o.take(); } Inside tokio, it uses mockall:mock! to create a MockFile, and then does `impl Read for &'_ MockFile`. However, since `mockall` is a dev dependency of tokio and we don't include dev dependencies of dependencies, rust-analyzer just sees `impl Read for &'_ NoSuchType`. Instead, exclude traits whose self type is error. AI disclosure: Partially written by Codex and GPT-5.5