MDEV-17399: JSON_TABLE: cleanup table dependency code

- Don't touch simplify_joins()
- All dependencies caused by JSON_TABLE(...) are now added by
  add_table_function_dependencies().

sql/json_table.cc

@@ -1153,9 +1153,8 @@ int Table_function_json_table::setup(THD *thd, TABLE_LIST *sql_table,
 
   if (m_dep_tables)
   {
-    sql_table->dep_tables|= m_dep_tables;
     t->no_cache= TRUE;
-    if (unlikely(sql_table->dep_tables & sql_table->get_map()))
+    if (unlikely(m_dep_tables & sql_table->get_map()))
     {
       /* Table itself is used in the argument. */
       my_error(ER_WRONG_USAGE, MYF(0), "JSON_TABLE", "argument"); 
@@ -1308,8 +1307,9 @@ static void add_extra_deps(List<TABLE_LIST> *join_list, table_map deps)
 
 /*
   @brief
-    Add extra dependencies implied by table functions so that the join
-    optimizer does not construct "dead-end" join prefixes.
+    Add table dependencies that are directly caused by table functions, also
+    add extra dependencies so that the join optimizer does not construct
+    "dead-end" join prefixes.
 
   @detail
     There are two kinds of limitations on join order:
@@ -1321,6 +1321,9 @@ static void add_extra_deps(List<TABLE_LIST> *join_list, table_map deps)
     current table in the query text. The table maybe outside of the current
     nested join and/or inside another nested join.
 
+    One may think that adding dependency according to #2 would be sufficient,
+    but this is not the case.
+
     @example
 
       select ...
@@ -1387,7 +1390,10 @@ table_map add_table_function_dependencies(List<TABLE_LIST> *join_list,
                                              nested_join->used_tables);
     }
     else if (table->table_function)
+    {
+      table->dep_tables |= table->table_function->used_tables();
       res |= table->dep_tables;
+    }
   }
   res= res & ~nest_tables & ~PSEUDO_TABLE_BITS;
   // Then, make all "peers" have them:

sql/sql_select.cc

@@ -16546,7 +16546,7 @@ simplify_joins(JOIN *join, List<TABLE_LIST> *join_list, COND *conds, bool top,
       if (table->outer_join && !table->embedding && table->table)
         table->table->maybe_null= FALSE;
       table->outer_join= 0;
-      if (!(straight_join || table->straight || table->table_function))
+      if (!(straight_join || table->straight))
       {
         table->dep_tables= 0;
         TABLE_LIST *embedding= table->embedding;