Property wrapper initialisation issues

Using Swift
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1

tl;dr How do I ensure my a property wrapper's init() is called when wrapped by another property wrapper, and how do I get to keep those values when decoding?

struct Cow: Decodable {
    @Rules(deletion: .cascade) var field1: Field
    @Wrapper @Rules(deletion: .nullify) var field2: Field
}

When I decode this the following calls occur:

- Rules<Field>.init(deletion: .cascade)
- Wrapper<Rules<Field>>.init()
> Cow.init(from:)
	> Rules<Field>.init(from:)
		- Field.init(from:)
	< Rules<Field>.init(from:)
	- Rules<Field>.deinit
	> Wrapper<Rules<Field>>.init(from:)
		> Rules<Field>.init(from:)
			- Field.init(from:)
		< Rules<Field>.init(from:)
	< Wrapper<Rules<Field>>.init(from:)
	- Wrapper<Rules<Field>>.deinit
< Cow.init(from:)

Two problems occur:

  • Rules<Field>.init(deletion: .cascade) is overwritten but the later Rules<Field>.init(from:)
  • Rules<Field>.init(deletion: .nullify) is not called at all.

I can see why the overwrite happens, but very much wish to avoid. The non-call is just plain weird.