return-ref on functions doesn't compile

[nikomatsakis]

#[salsa::tracked(return_ref)]
fn test(db: &dyn salsa::Database) -> Vec<u32> {
    vec![]
}

doesn't compile (or something like it).

[MichaReiser]

Interesting. We use this very intensively but only with custom DBs.

[ShoyuVanilla]

#[salsa::tracked(return_ref)]
fn test(db: &dyn salsa::Database) -> Vec<u32> {
    vec![]
}

doesn't compile (or something like it).

I haven't bisected yet but his function compiles well on latest master. Maybe it was somewhat other one like it or fixed somehow?