protocol P {}

protocol Q {
  associatedtype T: P
  func foo(_: T)
}

enum A: P {}

enum B: Q {
  func foo(_: A) {}
}

enum E<T> where T: P {}

extension E {
  @_specialize(exported: true, where U == B, T == A)
  func bar<U>(as: U.Type) where U: Q, U.T == T {}
}

redundant-constraint.swift:25:50: warning: redundant same-type constraint 'T' == 'A' @_specialize(exported: true, where U == B, T == A) ^ redundant-constraint.swift:25:42: note: same-type constraint 'U.T' == 'A' implied here @_specialize(exported: true, where U == B, T == A)

redundant-constraint.swift:25:6: error: too few type parameters are specified in '_specialize' attribute (got 1, but expected 2)
    @_specialize(exported: true, where U == B)
     ^
redundant-constraint.swift:25:6: error: Missing constraint for 'T' in '_specialize' attribute
    @_specialize(exported: true, where U == B)