Function dyn_cast_raw 

pub unsafe fn dyn_cast_raw<T: SupportsInterfaces + ?Sized, DynInterface, X: Deref<Target = T>, Y, A>(
    x: X,
    into_raw_parts: fn(X) -> (*const T, A),
    from_raw_parts: unsafe fn(*const DynInterface, A) -> Y,
) -> Option<Y>
where
    DynInterface: Pointee<Metadata = DynMetadata<DynInterface>> + ?Sized + 'static,

Generic runtime-checking safe cast for immutable smart pointers.

Intended for creating specific casting functions for custom smart pointers.

Safety

The function converts original smart pointer to a (possibly thick) immutable raw pointer using the into_raw_parts callback, then forms new thick immutable raw pointer replacing metadata with DynMetadata<DynInterface>, then calls the from_raw_parts unsafe callback to construct smart pointer from the last pointer. Calling the dyn_cast_raw_mut function is safe iff this last from_raw_parts call is safe.