MDEV-32586 incorrect error about cyclic reference about JSON type virtual column

remove the hack where NO_DEFAULT_VALUE_FLAG was temporarily removed
from a field to initialize DEFAULT() functions in CHECK constraints
while disabling self-reference field checks.

Instead, initialize DEFAULT() functions in CHECK explicitly,
don't call check_field_expression_processor() for CHECK at all.

mysql-test/main/check_constraint.result

@@ -308,5 +308,15 @@ t1	CREATE TABLE `t1` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
 drop table t1;
 #
+# MDEV-32586 incorrect error about cyclic reference about JSON type virtual column
+#
+create table t1 (a int, b json as (a));
+drop table t1;
+create table t1 (a int, b int as (a) check (b > 0));
+insert t1 (a) values (1);
+insert t1 (a) values (-1);
+ERROR 23000: CONSTRAINT `t1.b` failed for `test`.`t1`
+drop table t1;
+#
 # End of 10.4 tests
 #

mysql-test/main/check_constraint.test

@@ -231,6 +231,19 @@ alter table t1 force;
 show create table t1;
 drop table t1;
 
+--echo #
+--echo # MDEV-32586 incorrect error about cyclic reference about JSON type virtual column
+--echo #
+
+create table t1 (a int, b json as (a));
+drop table t1;
+
+create table t1 (a int, b int as (a) check (b > 0));
+insert t1 (a) values (1);
+--error ER_CONSTRAINT_FAILED
+insert t1 (a) values (-1);
+drop table t1;
+
 --echo #
 --echo # End of 10.4 tests
 --echo #

sql/item.cc

@@ -9412,6 +9412,11 @@ bool Item_default_value::eq(const Item *item, bool binary_cmp) const
 
 
 bool Item_default_value::check_field_expression_processor(void *)
+{
+  return Item_default_value::update_func_default_processor(0);
+}
+
+bool Item_default_value::update_func_default_processor(void *)
 {
   field->default_value= ((Item_field *)(arg->real_item()))->field->default_value;
   return 0;

sql/item.h

@@ -2080,6 +2080,7 @@ class Item: public Value_source,
   }
   virtual bool check_field_expression_processor(void *arg) { return 0; }
   virtual bool check_func_default_processor(void *arg) { return 0; }
+  virtual bool update_func_default_processor(void *arg) { return 0; }
   /*
     Check if an expression value has allowed arguments, like DATE/DATETIME
     for date functions. Also used by partitioning code to reject
@@ -6544,6 +6545,7 @@ class Item_default_value : public Item_field
   bool update_vcol_processor(void *arg) { return 0; }
   bool check_field_expression_processor(void *arg);
   bool check_func_default_processor(void *arg) { return true; }
+  bool update_func_default_processor(void *arg);
   bool register_field_in_read_map(void *arg);
 
   bool walk(Item_processor processor, bool walk_subquery, void *args)

sql/table.cc

@@ -1074,19 +1074,9 @@ bool parse_vcol_defs(THD *thd, MEM_ROOT *mem_root, TABLE *table,
       return vcol &&
              vcol->expr->walk(&Item::check_field_expression_processor, 0, field);
     }
-    static bool check_constraint(Field *field, Virtual_column_info *vcol)
-    {
-      uint32 flags= field->flags;
-      /* Check constraints can refer it itself */
-      field->flags|= NO_DEFAULT_VALUE_FLAG;
-      const bool res= check(field, vcol);
-      field->flags= flags;
-      return res;
-    }
     static bool check(Field *field)
     {
       if (check(field, field->vcol_info) ||
-          check_constraint(field, field->check_constraint) ||
           check(field, field->default_value))
         return true;
       return false;
@@ -1300,11 +1290,16 @@ bool parse_vcol_defs(THD *thd, MEM_ROOT *mem_root, TABLE *table,
 
   /* Check that expressions aren't referring to not yet initialized fields */
   for (field_ptr= table->field; *field_ptr; field_ptr++)
+  {
     if (check_vcol_forward_refs::check(*field_ptr))
     {
       *error_reported= true;
       goto end;
     }
+    if ((*field_ptr)->check_constraint)
+        (*field_ptr)->check_constraint->expr->
+          walk(&Item::update_func_default_processor, 0, *field_ptr);
+  }
 
   table->find_constraint_correlated_indexes();