in 91bbc55 - the mechanism for detecting a derive macro has changed, in such a way that only works on rust 1.52+ (probably because of rust-lang/rust#79078)

Here we can see that it cannot find the implementation for Default (either in the code lens, "0 implementations", and in the unresolvedReference scope in Foo::default()

unfortunately at work we are currently on a nightly on 1.51.0... so this causing a lot of broken analysis. :( took this opportunity to update us to a more recent nightly.