1

Before I go about filing a bug. Could anyone explain what might be going on in this example.

// Having Phase above causes an error in GameRules
#if PHASE_ABOVE
public protocol Phase {
  associatedtype RulesType: GameRules where RulesType.PhaseType == Self
}
#endif

public protocol GameRules {
  associatedtype ContextType: GameContext where ContextType.RulesType == Self
  associatedtype PhaseType: Phase where PhaseType.RulesType == Self
  associatedtype PlayerType: Player where PlayerType.RulesType == Self

  // Error here when `Phase` is above this protocol. Error: Instance method requirement cannot add constraint ... on Self
  mutating func executeTurn(forPlayer player: PlayerType)
}

// But having it below is fine
#if !PHASE_ABOVE
public protocol Phase {
  associatedtype RulesType: GameRules where RulesType.PhaseType == Self
}
#endif

public protocol GameContext : AnyObject {
  associatedtype RulesType: GameRules where RulesType.ContextType == Self
}

public protocol Player : AnyObject, Hashable {
  associatedtype RulesType: GameRules where RulesType.PlayerType == Self
}

tl;dr: Moving a protocol above another causes an error.

3

This seems to be an "improvement" over 4.0.3. There this just crashes the compiler.

4

Probably related to this:
https://bugs.swift.org/browse/SR-7353

5

Yeah possibly. Should I go ahead and attach my example to that ticket? And if they turn out to be different I’ll just make a new ticket.

6

I think you should file your example as a separate report, mentioning SR-7353 as possibly related.