MDEV-25292 Refactoring: moved select_field_count into Alter_info.

There is a need in MDEV-25292 to have both C_ALTER_TABLE and
select_field_count in one call. Semantically creation mode and field
count are two different things. Making creation mode negative
constants and field count positive variable into one parameter seems
to be a lazy hack for not making the second parameter.

select_count does not make sense without alter_info->create_list, so
the natural way is to hold it in Alter_info too. select_count is now
stored in member select_field_count.

sql/handler.cc

@@ -8187,7 +8187,7 @@ bool Table_scope_and_contents_source_st::vers_fix_system_fields(
 
 bool Table_scope_and_contents_source_st::vers_check_system_fields(
         THD *thd, Alter_info *alter_info, const Lex_table_name &table_name,
-        const Lex_table_name &db, int select_count)
+        const Lex_table_name &db)
 {
   if (!(options & HA_VERSIONED_TABLE))
     return false;
@@ -8208,7 +8208,7 @@ bool Table_scope_and_contents_source_st::vers_check_system_fields(
          SELECT go last there.
        */
       bool is_dup= false;
-      if (fieldnr >= alter_info->create_list.elements - select_count)
+      if (fieldnr >= alter_info->field_count())
       {
         List_iterator<Create_field> dup_it(alter_info->create_list);
         for (Create_field *dup= dup_it++; !is_dup && dup != f; dup= dup_it++)
@@ -8616,10 +8616,9 @@ bool Table_period_info::check_field(const Create_field* f,
 
 bool Table_scope_and_contents_source_st::check_fields(
   THD *thd, Alter_info *alter_info,
-  const Lex_table_name &table_name, const Lex_table_name &db, int select_count)
+  const Lex_table_name &table_name, const Lex_table_name &db)
 {
-  return vers_check_system_fields(thd, alter_info,
-                                  table_name, db, select_count) ||
+  return vers_check_system_fields(thd, alter_info, table_name, db) ||
     check_period_fields(thd, alter_info);
 }
 

sql/handler.h

@@ -2257,8 +2257,7 @@ struct Table_scope_and_contents_source_st:
   bool fix_period_fields(THD *thd, Alter_info *alter_info);
   bool check_fields(THD *thd, Alter_info *alter_info,
                     const Lex_table_name &table_name,
-                    const Lex_table_name &db,
-                    int select_count= 0);
+                    const Lex_table_name &db);
   bool check_period_fields(THD *thd, Alter_info *alter_info);
 
   bool vers_fix_system_fields(THD *thd, Alter_info *alter_info,
@@ -2266,8 +2265,7 @@ struct Table_scope_and_contents_source_st:
 
   bool vers_check_system_fields(THD *thd, Alter_info *alter_info,
                                 const Lex_table_name &table_name,
-                                const Lex_table_name &db,
-                                int select_count= 0);
+                                const Lex_table_name &db);
 
 };
 

sql/sql_alter.h

@@ -96,6 +96,7 @@ class Alter_info
   List<Alter_rename_key>        alter_rename_key_list;
   // List of columns, used by both CREATE and ALTER TABLE.
   List<Create_field>            create_list;
+  uint                          select_field_count;
   // Indexes whose ignorability needs to be changed.
   List<Alter_index_ignorability>  alter_index_ignorability_list;
   List<Virtual_column_info>     check_constraint_list;
@@ -118,6 +119,7 @@ class Alter_info
 
 
   Alter_info() :
+  select_field_count(0),
   flags(0), partition_flags(0),
     keys_onoff(LEAVE_AS_IS),
     num_parts(0),
@@ -134,6 +136,7 @@ class Alter_info
     create_list.empty();
     alter_index_ignorability_list.empty();
     check_constraint_list.empty();
+    select_field_count= 0;
     flags= 0;
     partition_flags= 0;
     keys_onoff= LEAVE_AS_IS;
@@ -234,6 +237,11 @@ class Alter_info
    */
   enum_alter_table_algorithm algorithm(const THD *thd) const;
 
+  uint field_count() const
+  {
+    return create_list.elements - select_field_count;
+  }
+
 private:
   Alter_info &operator=(const Alter_info &rhs); // not implemented
   Alter_info(const Alter_info &rhs);            // not implemented

sql/sql_insert.cc

@@ -4490,7 +4490,7 @@ TABLE *select_create::create_table_from_items(THD *thd, List<Item> *items,
   TABLE tmp_table;		// Used during 'Create_field()'
   TABLE_SHARE share;
   TABLE *table= 0;
-  uint select_field_count= items->elements;
+  alter_info->select_field_count= items->elements;
   /* Add selected items to field list */
   List_iterator_fast<Item> it(*items);
   Item *item;
@@ -4550,8 +4550,7 @@ TABLE *select_create::create_table_from_items(THD *thd, List<Item> *items,
 
   if (create_info->check_fields(thd, alter_info,
                                 create_table->table_name,
-                                create_table->db,
-                                select_field_count))
+                                create_table->db))
     DBUG_RETURN(NULL);
 
   DEBUG_SYNC(thd,"create_table_select_before_create");
@@ -4587,7 +4586,7 @@ TABLE *select_create::create_table_from_items(THD *thd, List<Item> *items,
                                   &create_table->db,
                                   &create_table->table_name,
                                   create_info, alter_info, NULL,
-                                  select_field_count, create_table))
+                                  C_ORDINARY_CREATE, create_table))
   {
     DEBUG_SYNC(thd,"create_table_select_before_open");
 

sql/sql_table.cc

@@ -2741,7 +2741,6 @@ mysql_prepare_create_table(THD *thd, HA_CREATE_INFO *create_info,
   List_iterator_fast<Create_field> it(alter_info->create_list);
   List_iterator<Create_field> it2(alter_info->create_list);
   uint total_uneven_bit_length= 0;
-  int select_field_count= C_CREATE_SELECT(create_table_mode);
   bool tmp_table= create_table_mode == C_ALTER_TABLE;
   const bool create_simple= thd->lex->create_simple();
   bool is_hash_field_needed= false;
@@ -2781,7 +2780,7 @@ mysql_prepare_create_table(THD *thd, HA_CREATE_INFO *create_info,
     DBUG_RETURN(TRUE);
   }
 
-  select_field_pos= alter_info->create_list.elements - select_field_count;
+  select_field_pos= alter_info->field_count();
   null_fields= 0;
   create_info->varchar= 0;
   max_key_length= file->max_key_length();
@@ -2956,7 +2955,7 @@ mysql_prepare_create_table(THD *thd, HA_CREATE_INFO *create_info,
    from the select tables. This order may differ on master and slave. We
    therefore mark it as unsafe.
   */
-  if (select_field_count > 0 && auto_increment)
+  if (alter_info->select_field_count > 0 && auto_increment)
     thd->lex->set_stmt_unsafe(LEX::BINLOG_STMT_UNSAFE_CREATE_SELECT_AUTOINC);
 
   /* Create keys */

sql/sql_table.h

@@ -124,11 +124,10 @@ bool add_keyword_to_query(THD *thd, String *result, const LEX_CSTRING *keyword,
   (which should be the number of fields in the SELECT ... part), and other
   cases use constants as defined below.
 */
-#define C_CREATE_SELECT(X)        ((X) > 0 ? (X) : 0)
 #define C_ORDINARY_CREATE         0
-#define C_ALTER_TABLE            -1
-#define C_ALTER_TABLE_FRM_ONLY   -2
-#define C_ASSISTED_DISCOVERY     -3
+#define C_ALTER_TABLE             1
+#define C_ALTER_TABLE_FRM_ONLY    2
+#define C_ASSISTED_DISCOVERY      3
 
 int mysql_create_table_no_lock(THD *thd,
                                DDL_LOG_STATE *ddl_log_state,