Macro arch_union_wrapper 

macro_rules! arch_union_wrapper {
    {} => { ... };
    {
        $vis:vis $wrapper:ident( $ty:ident );
        $($token:tt)*
    } => { ... };
}

Build the wrapper type around a UABI specific union.

arch_union_wrapper is invoked like so:

arch_union_wrapper! {
    Wrapper(wrappee_name);
}

where Wrapper is the name of the wrapper type being generated, and wrappee_name is the identifier of the union type of wrap. This will allow to read and write Wrapper object using the arch specific read/write methods of the memory manager passing a WrapperPtr reference.