// RUN: %target-typecheck-verify-swift

struct Foo<T> {}

protocol P1 {
    associatedtype A // expected-note {{protocol requires nested type 'A'; do you want to add it?}}
}
extension Foo: P1 where A : P1 {} // expected-error {{circular reference}}
// expected-note@-1 {{while resolving type 'A'}}
// expected-note@-2 {{through reference here}}
// expected-error@-3 {{type 'Foo<T>' does not conform to protocol 'P1'}}