Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

mcs/tests/gtest-253.cs

@@ -0,0 +1,45 @@
+using System;
+using SCG = System.Collections.Generic;
+
+public interface IExtensible<T>
+{
+	void AddAll<U> (SCG.IEnumerable<U> items)
+		where U : T;
+}
+
+public abstract class CollectionValueTester<R,S>
+	where R : IExtensible<S>
+{
+	protected R collection;
+}
+
+public class ExtensibleTester<U> : CollectionValueTester<U,int>
+	where U : IExtensible<int>
+{
+	public ExtensibleTester (U u)
+	{
+		this.collection = u;
+	}
+
+	public void Direct()
+	{
+		collection.AddAll<int> (new int[] { });
+	}
+}
+
+public class Extensible<V> : IExtensible<V>
+{
+	public void AddAll<W> (SCG.IEnumerable<W> items)
+		where W : V
+	{ }
+}
+
+class X
+{
+	public static void Main ()
+	{
+		Extensible<int> ext = new Extensible<int> ();
+		ExtensibleTester<Extensible<int>> tester = new ExtensibleTester<Extensible<int>> (ext);
+		tester.Direct ();
+	}
+}