Put @_moveOnly type attribute behind the move only experimental flag.

Just forgot to do this.

Author: gottesmm

lib/Sema/TypeCheckAttr.cpp

@@ -1950,6 +1950,13 @@ void AttributeChecker::visitFinalAttr(FinalAttr *attr) {
 }
 
 void AttributeChecker::visitMoveOnlyAttr(MoveOnlyAttr *attr) {
+  if (!D->getASTContext().LangOpts.hasFeature(Feature::MoveOnly)) {
+    auto error =
+        diag::experimental_moveonly_feature_can_only_be_used_when_enabled;
+    diagnoseAndRemoveAttr(attr, error);
+    return;
+  }
+
   if (isa<NominalTypeDecl>(D))
     return;
 

test/Sema/moveonly_decl_attr.swift

@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift -parse-stdlib -disable-availability-checking -verify-syntax-tree
+// RUN: %target-typecheck-verify-swift -parse-stdlib -disable-availability-checking -verify-syntax-tree -enable-experimental-move-only
 
 import Swift