Merge pull request swiftlang#14918 from DougGregor/class-in-constrained-ext-rdar37840927

Author: swift-ci

test/Interpreter/class_in_constrained_extension.swift

@@ -0,0 +1,16 @@
+// RUN: %target-run-simple-swift | %FileCheck %s
+// REQUIRES: executable_test
+
+class Foo {}
+
+extension Array where Element == Foo {
+  class Bar { var foo = Foo() }
+  
+  init(withAThing: String) {
+    self = [Bar(), Bar(), Bar()].map { $0.foo }
+  }
+}
+
+// CHECK: [main.Foo, main.Foo, main.Foo]
+let foos = [Foo](withAThing: "Hi")
+print(foos)