Imported Upstream version 3.8.0

Former-commit-id: 6a76a29bd07d86e57c6c8da45c65ed5447d38a61

mcs/tests/gtest-616.cs

@@ -0,0 +1,37 @@
+using System;
+
+struct S : IDisposable
+{
+	public void Dispose ()
+	{
+	}
+}
+
+class A<T> where T : IDisposable
+{
+	public virtual bool Test<U> (U u) where U : T
+	{
+		using (u) {
+			return false;
+		}
+	}
+}
+
+class B : A<S>
+{
+	public override bool Test<U> (U u)
+	{
+		using (u) {
+			return true;
+		}
+	}
+
+	public static int Main ()
+	{
+		var b = new B ();
+		if (!b.Test (new S ()))
+			return 1;
+
+		return 0;
+	}
+}