In the test case query above we actually have 2 instances of the recursive CTE cte_r, because cte_e is used twice in the main query. Accordingly 2 TABLE_LIST structures are created for the recursive reference r used in the specification of these two instances of cte_r. In debugger we see that starting from 10.4 TABLE_LIST::init_derived() is called for the recursive reference used in the specification of the first instance of cte_r, but is not called for the recursive reference used in the specification of the second instance of cte_r. Yet this function must be called for the table reference of any derived table. TABLE_LIST::init_derived() is not called for the recursive reference of the second instance of cte_r because the SELECT specifying this instance was not included in the global list of all selects. It has happened because the following code

   old_lex->all_selects_list=

     (st_select_lex*) (lex->all_selects_list->

                      insert_chain_before(

                        (st_select_lex_node **) &(old_lex->all_selects_list),

                         with_select));

from With_element::clone_parsed_spec() assumes that with_select that points to the SELECT_LEX created for the specification of the second instance of cte_r is the last select the in the chain of the selects created when the specification of cte_e is parsed for the second reference to this CTE. It is realy so for 10.2 and 10.3, but the new grammar of 10.4 constructs SELECT_LEX objects in a different order and they are included into all_select_list in a different order.

This problem of missing SELECTs in the all_select_list does not lead to similar failures for the queries that use only non-recursive CTEs, such as the following one:

with cte_e as (

  with cte_o as (

    with cte_i as (select a from t1 group by a)

  select a from cte_i

 ) select a from cte_o group by a

) select * from cte_e s1, cte_e s2 where s1.a=s2.a;

.
Here TABLE_LIST::init_derived() is invoked for the second reference to cte_i occurred the the select created for the second instance of CTE cte_e. It is invoked by the code:

  if (!derived->is_with_table_recursive_reference() &&

       derived->init_derived(thd, FALSE))

     goto exit;

from mysql_derived_prepare().

OK to push

A fix for this bug was pushed into 10.4. It should be merged upstream as it is.