Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

mcs/errors/cs0458-15.cs

@@ -0,0 +1,26 @@
+// CS0458: The result of the expression is always `null' of type `short?'
+// Line: 24
+// Compiler options: -warnaserror -warn:2
+
+struct S
+{
+	public static short operator + (S s, S i)
+	{
+		return 2;
+	}
+
+	public static int? operator + (S? s, int? i)
+	{
+		return 2;
+	}
+
+}
+
+class C
+{
+	public static void Main ()
+	{
+		S? s = new S ();
+		var x = s + (S?)null;
+	}
+}