Comment by Brian T. Kelley (JIRA)

Also filed FB8621431.

Thank you for investigating this and filing the issue!

The problem is that we're not re-writing assign_by_wrapper to re-assignment of the backing property wrapper in the case where it has already been initialized. Regardless of property observers, we can't call the getter or setter of the wrapped value before all of self is initialized because of enclosing self property wrappers, and it would be really unfortunate to not allow this kind of code for such property wrappers:

class C {
  @Published var value = 10
  var str: String

  init(value: Int, str: String) {
    self.value = value
    self.str = str
  } 
}

#33923

Just realized I forgot to resolve this. Could you please verify in the latest Xcode or Swift 5.3.2? Thank you!