```
2021.10.22 07:14:33.963099 [ 3451059 ] {} <Error> Application: DB::Exception: Syntax error (in file ./user_defined/function_a_function.sql): failed at position 39 ('->'): -> ch(2)

$ cat ./user_defined/function_a_function.sql
CREATE FUNCTION a_function AS tuple() -> ch(2)
```
{
            if (i != 0)
                settings.ostr << ", ";
            bool special_hilite = false;
            if (i == 1 && special_hilite_regexp)
                special_hilite = highlightStringLiteralWithMetacharacters(arguments->children[i], settings, "|()^$.[]?*+{:-");
            if (!special_hilite)
                arguments->children[i]->formatImpl(settings, state, nested_dont_need_parens);
        }
    }
    if ((arguments && !arguments->children.empty()) || !no_empty_args)
        settings.ostr << (settings.hilite ? hilite_function : "") << ')';
    settings.ostr << (settings.hilite ? hilite_none : "");
    if (!is_window_function)
    {
        return;
    }
    settings.ostr << " OVER ";
    if (!window_name.empty())
    {
        settings.ostr << backQuoteIfNeed(window_name);
    }
    else
    {
        settings.ostr << "(";
        window_definition->formatImpl(settings, state, frame);
        settings.ostr << ")";
    }
}
String getFunctionName(const IAST * ast)