Imported Upstream version 5.12.0.220

Former-commit-id: c477e03582759447177c6d4bf412cd2355aad476

mcs/tests/gtest-647.cs

@@ -0,0 +1,34 @@
+using System;
+
+public class Program
+{
+	public static int Main ()
+	{
+		int B = default (MyStruct?); 
+		if (MyStruct.counter != 1)
+			return 1;
+
+		switch (default (MyStruct?)) {
+			case 0:
+				break;
+			default:
+				return 2;
+		}
+
+		if (MyStruct.counter != 2)
+			return 4;
+
+		return 0;
+	}
+
+	public struct MyStruct
+	{
+		public static int counter;
+
+		public static implicit operator int (MyStruct? s)
+		{
+			++counter;
+			return 0;
+		}
+	}
+}