Imported Upstream version 5.10.0.47

Former-commit-id: d0813289fa2d35e1f8ed77530acb4fb1df441bc0

mcs/errors/cs1644-55.cs

@@ -0,0 +1,11 @@
+// CS1644: Feature `byref locals and returns' cannot be used because it is not part of the C# 6.0 language specification
+// Line: 9
+// Compiler options: -langversion:6
+
+class Text
+{
+	static ref long Foo ()
+	{
+		throw new System.NotImplementedException ();
+	}
+}