Merge pull request #12483 from practicalswift/swiftc-28863-t-is-archetypetype-t-isexistentialtype-expected-a-class-archetype-or-existential

[swiftc (69 vs. 5600)] Add crasher in swift::TypeBase::getSuperclassForDecl

Author: practicalswift

validation-test/compiler_crashers/28863-t-is-archetypetype-t-isexistentialtype-expected-a-class-archetype-or-existential.swift

@@ -0,0 +1,13 @@
+// This source file is part of the Swift.org open source project
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+
+// REQUIRES: asserts
+// RUN: not --crash %target-swift-frontend %s -emit-ir
+class a
+class a<a{{}class a<a{var f=a
+& ManagedBuffer
+protocol a