[Tests] NFC: Add a test-case for rdar://123336457

Author: xedin

test/decl/protocol/req/rdar123336457.swift

@@ -0,0 +1,34 @@
+// RUN: %target-typecheck-verify-swift -enable-experimental-associated-type-inference
+// RUN: %target-typecheck-verify-swift -disable-experimental-associated-type-inference
+
+protocol Task1: AnyObject {
+}
+
+protocol Task2: AnyObject {
+}
+
+class TaskImpl : Task2 {
+}
+
+protocol TaskResult {
+  associatedtype Task
+
+  var tasks: [Task] { get }
+
+  func removeMatchedTask(_ task: Task)
+  func match(_ task: Task) -> Bool
+}
+
+extension TaskResult where Task == Task1 {
+  func match(_ task: Task) -> Bool { false }
+}
+
+extension TaskResult where Task: Task2 {
+  func match(_ task: Task) -> Bool { false }
+}
+
+final class Results: TaskResult {
+  var tasks: [TaskImpl] = []
+
+  func removeMatchedTask(_ task: TaskImpl) {}
+}