Function rustdoc::clean::utils::get_real_types

pub(crate) fn get_real_types(
    generics: &Generics, 
    arg: &Type, 
    cx: &DocContext<'_>, 
    recurse: i32
) -> FxHashSet<(Type, TypeKind)>

The point of this function is to replace bounds with types.

i.e. [T, U] when you have the following bounds: T: Display, U: Option<T> will return [Display, Option] (we just returns the list of the types, we don't care about the wrapped types in here).