Imported Upstream version 5.10.0.47

Former-commit-id: d0813289fa2d35e1f8ed77530acb4fb1df441bc0

mcs/errors/cs8148.cs

@@ -0,0 +1,15 @@
+// CS8148: `B.Foo()': must not return by reference to match overridden member `A.Foo()'
+// Line: 11
+
+public abstract class A
+{
+	public abstract int Foo ();
+}
+
+public class B : A
+{
+	public override ref int Foo ()
+	{
+
+	}
+}