Merge pull request #7091 from practicalswift/swiftc-28672-result-case-not-implemented

diff --git a/validation-test/compiler_crashers/28672-result-case-not-implemented.swift b/validation-test/compiler_crashers/28672-result-case-not-implemented.swift
new file mode 100644
index 0000000..f9489a2
--- /dev/null
+++ b/validation-test/compiler_crashers/28672-result-case-not-implemented.swift
@@ -0,0 +1,15 @@
+// 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: deterministic-behavior
+// REQUIRES: asserts
+// RUN: not --crash %target-swift-frontend %s -emit-ir
+a
+V!in{
+class B{func b(UInt=1 + 1 + 1 as?Int)
+{
+n?Int