public static void ReportCannotApplyUnaryOperator(this ICollection <Diagnostic> diagnostics, TextSpan span, UnaryOperatorKind operatorKind, Type type)
        {
            var operatorName     = operatorKind.ToDisplayName();
            var argumentTypeName = type.ToDisplayName();

            diagnostics.Report(span, DiagnosticId.CannotApplyUnaryOperator, operatorName, argumentTypeName);
        }