Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

mcs/tests/gtest-467.cs

@@ -0,0 +1,24 @@
+using System;
+
+struct S
+{
+	public static int Main ()
+	{
+		S? s = null;
+		A a = s;
+		B b = (B) s;
+		return 0;
+	}
+}
+
+class A
+{
+	public static implicit operator A (S x)
+	{
+		return new B ();
+	}
+}
+
+class B : A
+{
+}