Type Alias Erased 

pub type Erased<T: Erasable> = ErasedData<impl Copy>;

A value of T that has been “erased” into some opaque storage type.

This is helpful for reducing the number of concrete instantiations needed during codegen when building the compiler.

Using an opaque type alias allows the type checker to enforce that Erased<T> and Erased<U> are still distinct types, while allowing monomorphization to see that they might actually use the same storage type.

Aliased Type

pub struct Erased<T: Erasable> {
    data: MaybeUninit<impl Copy>,
}

Fields

data: MaybeUninit<impl Copy>

We use MaybeUninit here to make sure it’s legal to store a transmuted value that isn’t actually of type Storage.

Layout

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.