MDEV-19377 Replace Virtual_column_info::field_type to Type_handler

sql/field.cc

@@ -10572,7 +10572,7 @@ bool Column_definition::check(THD *thd)
   if (vcol_info)
   {
     DBUG_ASSERT(vcol_info->expr);
-    vcol_info->set_field_type(real_field_type());
+    vcol_info->set_handler(type_handler());
     if (check_expression(vcol_info, &field_name, vcol_info->stored_in_db
                          ? VCOL_GENERATED_STORED : VCOL_GENERATED_VIRTUAL))
       DBUG_RETURN(TRUE);

sql/field.h

@@ -524,7 +524,8 @@ static inline const char *vcol_type_name(enum_vcol_info_type type)
   - whether the field is used in a partitioning expression
 */
 
-class Virtual_column_info: public Sql_alloc
+class Virtual_column_info: public Sql_alloc,
+                           private Type_handler_hybrid_field_type
 {
 private:
   enum_vcol_info_type vcol_type; /* Virtual column expression type */
@@ -532,7 +533,6 @@ class Virtual_column_info: public Sql_alloc
     The following data is only updated by the parser and read
     when a Create_field object is created/initialized.
   */
-  enum_field_types field_type;   /* Real field type*/
   /* Flag indicating that the field used in a partitioning expression */
   bool in_partitioning_expr;
 
@@ -546,8 +546,8 @@ class Virtual_column_info: public Sql_alloc
   uint flags;
 
   Virtual_column_info()
-  : vcol_type((enum_vcol_info_type)VCOL_TYPE_NONE),
-    field_type((enum enum_field_types)MYSQL_TYPE_VIRTUAL),
+   :Type_handler_hybrid_field_type(&type_handler_null),
+    vcol_type((enum_vcol_info_type)VCOL_TYPE_NONE),
     in_partitioning_expr(FALSE), stored_in_db(FALSE),
     utf8(TRUE), expr(NULL), flags(0)
   {
@@ -568,14 +568,11 @@ class Virtual_column_info: public Sql_alloc
     DBUG_ASSERT(vcol_type != VCOL_TYPE_NONE);
     return vcol_type_name(vcol_type);
   }
-  enum_field_types get_real_type() const
-  {
-    return field_type;
-  }
-  void set_field_type(enum_field_types fld_type)
+  void set_handler(const Type_handler *handler)
   {
     /* Calling this function can only be done once. */
-    field_type= fld_type;
+    DBUG_ASSERT(type_handler() == &type_handler_null);
+    Type_handler_hybrid_field_type::set_handler(handler);
   }
   bool is_stored() const
   {

sql/item.h

@@ -7130,7 +7130,7 @@ bool fix_escape_item(THD *thd, Item *escape_item, String *tmp_str,
 
 inline bool Virtual_column_info::is_equal(const Virtual_column_info* vcol) const
 {
-  return field_type == vcol->get_real_type()
+  return type_handler()  == vcol->type_handler()
       && stored_in_db == vcol->is_stored()
       && expr->eq(vcol->expr, true);
 }