Imported Upstream version 5.8.0.22

Former-commit-id: df344e34b07851d296efb3e6604c8db42b6f7aa3

mcs/errors/cs8141-2.cs

@@ -0,0 +1,19 @@
+// CS8141:
+// Line: 11
+
+public interface I<T>
+{
+	int this[T arg] { get; set; }
+}
+
+public class C : I<(int a, int b)>
+{
+	public int this[(int c, int d) arg] {
+		get {
+			return 1;
+		}
+		set {
+
+		}
+	}
+}