MDEV-28294: set default role bypasses Replicate_Wild_Ignore_Table: mysql.%bb-10.4-MDEV-28294-merge

Problem:
========
When replicating SET DEFAULT ROLE, the pre-update check (i.e. that
in set_var_default_role::check()) tries to validate the existence of
the given rules/user even when the targeted tables are ignored. When
previously issued CREATE USER/ROLE commands are ignored by the
replica because of the replication filtering rules, this results in
an error because the targeted data does not exist.

Solution:
========
Before checking that the given rules/user exist of a SET DEFAULT
ROLE command, first ensure that the mysql.user and
mysql.roles_mapping tables are not excluded by replication filters.

Reviewed By
============
Andrei Elkin <andrei.elkin@mariadb.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 6a1b849b912..2b718972fc6 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -3661,6 +3661,39 @@ mysql_execute_command(THD *thd)
                  MYF(0));
       DBUG_RETURN(0);
     }
+
+    /*
+      Check if the SET command will modify a table that should be ignored in
+      replication.
+    */
+    if (lex->sql_command == SQLCOM_SET_OPTION)
+    {
+      List<set_var_base> *lex_var_list= &lex->var_list;
+      List_iterator_fast<set_var_base> it(*lex_var_list);
+      set_var_base *set_var;
+      while ((set_var=it++))
+      {
+        TABLE_LIST *tables;
+        set_var->get_modified_tables(&tables);
+        if (tables && all_tables_not_ok(thd, tables))
+        {
+          /*
+            Used in MTR to prove that the event was ignored _here_
+          */
+          DBUG_EXECUTE_IF(
+              "sync_set_var_rpl_filtered",
+              DBUG_ASSERT(!debug_sync_set_action(
+                  thd, STRING_WITH_LEN("now SIGNAL ignoring_event WAIT_FOR "
+                                       "ack_event_ignored"))););
+          /* warn the slave SQL thread */
+          my_message(ER_SLAVE_IGNORED_TABLE,
+                     ER_THD(thd, ER_SLAVE_IGNORED_TABLE), MYF(0));
+          DBUG_RETURN(0);
+        }
+      }
+    }
+
+
     /* 
        Execute deferred events first
     */