def _iter_available_targets(
        self,
        query: Query,
        include_empty: bool = False,
    ) -> Iterator[str]:
        """Iterate along a list of valid alias targets."""
        for selectable in query.selectables:
            select_info = selectable.select_info
            for alias in select_info.table_aliases:
                if alias.ref_str or include_empty:
                    yield alias.ref_str

    def _visit_queries(self, query: Query, visited: set) -> Iterator[LintResult]:
        select_info: Optional[SelectStatementColumnsAndTables] = None
        if query.selectables:
            select_info = query.selectables[0].select_info
            # How many table names are visible from here? If more than one then do
            # nothing.
            if select_info and len(select_info.table_aliases) == 1:
                fixable = True
                # :TRICKY: Subqueries in the column list of a SELECT can see tables
                # in the FROM list of the containing query. Thus, count tables at
                # the *parent* query level.
                possible_ref_tables = list(self._iter_available_targets(query))
                if query.parent:
                    possible_ref_tables  = list(
                        # Due to https://github.com/sqlfluff/sqlfluff/issues/5983
                        # include empty aliases for the purposes of our count
                        # to see if this is auto-fixable, but make sure we
                        # don't count the subquery itself
                        self._iter_available_targets(
                            query.parent,
                            include_empty=True,
                        )
                    )