Function eager_resolve_vars 

pub fn eager_resolve_vars<Infcx, T>(infcx: &Infcx, value: T) -> T
where
    Infcx: InferCtxtLike,
    T: TypeFoldable<<Infcx as InferCtxtLike>::Interner>,

Resolves ty, region, and const vars to their inferred values or their root vars.