add very basic test to ensure modules / interfaces for moveonly types work with library evolution

Author: kavon

test/ModuleInterface/Inputs/moveonly_simple.swift

@@ -1,12 +1,15 @@
+public enum SwiftCoin : ~Copyable {
+  case penny
+  case nickel
 
-public class Message { var s: String = "hello" }
-
-public struct FileDescriptor : ~Copyable {
-  public var x: Int = 0
-  public var msg: Message = Message()
+  init() { self = .penny }
 }
 
-public class FileHandle {
-  var file: FileDescriptor = FileDescriptor()
+// ensures old attribute still works.
+@_moveOnly public enum ObjCCoin {
+  case penny
+  case nickel
+
+  init() { self = .penny }
 }
 

test/ModuleInterface/moveonly_interface.swift

@@ -0,0 +1,25 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend -enable-library-evolution -module-name Hello -emit-module -o %t/Hello.swiftmodule -emit-module-interface-path %t/Hello.swiftinterface %S/Inputs/moveonly_simple.swift -swift-version 5
+// RUN: %FileCheck %s < %t/Hello.swiftinterface
+// RUN: %target-swift-frontend -emit-sil -verify -I %t %s -swift-version 5
+
+import Hello
+
+// CHECK:      #if compiler(>=5.3) && $MoveOnly
+// CHECK-NEXT:   public enum SwiftCoin : ~Swift.Copyable {
+
+// CHECK:      #if compiler(>=5.3) && $MoveOnly
+// CHECK-NEXT:   @_moveOnly public enum ObjCCoin {
+
+func eat(_ c: consuming SwiftCoin) {}
+func eat(_ c: consuming ObjCCoin) {}
+
+public func ensureItIsNonCopyable(_ c: consuming SwiftCoin) { // expected-error {{'c' consumed more than once}}
+  eat(c) // expected-note {{consuming use here}}
+  eat(c) // expected-note {{consuming use here}}
+}
+
+public func ensureItIsNonCopyable(_ c: consuming ObjCCoin) { // expected-error {{'c' consumed more than once}}
+  eat(c) // expected-note {{consuming use here}}
+  eat(c) // expected-note {{consuming use here}}
+}