(edited)

rintaro

struct A { } struct B { } protocol P { associatedtype Assoc = A } struct S<T>: P { } extension S where T == Int { typealias Assoc = B } print(S<String>.Assoc())

Version:

swift-4.2-DEVELOPMENT-SNAPSHOT-2018-05-29-a

Output:

B()

Error:

Version:

swift-4.1.1-RELEASE

Output:

B()

Error: