MDEV-29771 Server crashes in check_sequence_fields upon CREATE TABLE .. SEQUENCE=1 AS SELECT ..

Pass name separately for sequence check because sequence can be created with
CREATE TABLE (see https://mariadb.com/kb/en/create-table/#sequence )

mysql-test/suite/sql_sequence/create.result

@@ -716,4 +716,12 @@ CREATE SEQUENCE seq1 START WITH 2;
 CREATE TRIGGER s1 BEFORE UPDATE ON seq1 FOR EACH ROW SET @a= 5;
 ERROR HY000: Trigger's 'seq1' is view, temporary table or sequence
 DROP SEQUENCE seq1;
+#
+# MDEV-29771: Server crashes in check_sequence_fields upon
+# CREATE TABLE .. SEQUENCE=1 AS SELECT ..
+#
+create table s sequence=1 as select 1;
+ERROR HY000: Sequence 'test.s' table structure is invalid (Wrong number of columns)
+#
 # End of 10.4 test
+#

mysql-test/suite/sql_sequence/create.test

@@ -554,4 +554,14 @@ CREATE SEQUENCE seq1 START WITH 2;
 CREATE TRIGGER s1 BEFORE UPDATE ON seq1 FOR EACH ROW SET @a= 5;
 DROP SEQUENCE seq1;
 
+--echo #
+--echo # MDEV-29771: Server crashes in check_sequence_fields upon
+--echo # CREATE TABLE .. SEQUENCE=1 AS SELECT ..
+--echo #
+
+--error ER_SEQUENCE_INVALID_TABLE_STRUCTURE
+create table s sequence=1 as select 1;
+
+--echo #
 --echo # End of 10.4 test
+--echo #

sql/sql_sequence.cc

@@ -186,7 +186,8 @@ void sequence_definition::store_fields(TABLE *table)
     true        Failure
 */
 
-bool check_sequence_fields(LEX *lex, List<Create_field> *fields)
+bool check_sequence_fields(LEX *lex, List<Create_field> *fields,
+                           const LEX_CSTRING db, const LEX_CSTRING table_name)
 {
   Create_field *field;
   List_iterator_fast<Create_field> it(*fields);
@@ -234,8 +235,7 @@ bool check_sequence_fields(LEX *lex, List<Create_field> *fields)
 
 err:
   my_error(ER_SEQUENCE_INVALID_TABLE_STRUCTURE, MYF(0),
-           lex->first_select_lex()->table_list.first->db.str,
-           lex->first_select_lex()->table_list.first->table_name.str, reason);
+           db.str, table_name.str, reason);
   DBUG_RETURN(TRUE);
 }
 

sql/sql_sequence.h

@@ -162,6 +162,8 @@ class SEQUENCE_LAST_VALUE
 
 class Create_field;
 extern bool prepare_sequence_fields(THD *thd, List<Create_field> *fields);
-extern bool check_sequence_fields(LEX *lex, List<Create_field> *fields);
+extern bool check_sequence_fields(LEX *lex, List<Create_field> *fields,
+                                  const LEX_CSTRING db,
+                                  const LEX_CSTRING table_name);
 extern bool sequence_insert(THD *thd, LEX *lex, TABLE_LIST *table_list);
 #endif /* SQL_SEQUENCE_INCLUDED */

sql/sql_table.cc

@@ -3471,7 +3471,8 @@ mysql_prepare_create_table(THD *thd, HA_CREATE_INFO *create_info,
     }
 
     /* The user specified fields: check that structure is ok */
-    if (check_sequence_fields(thd->lex, &alter_info->create_list))
+    if (check_sequence_fields(thd->lex, &alter_info->create_list,
+                              db, table_name))
       DBUG_RETURN(TRUE);
   }