MDEV-15940

This script crashes the server:

DELIMITER $$

BEGIN NOT ATOMIC

  DECLARE v INT;

  DECLARE cur CURSOR FOR VALUES(7);

  OPEN cur;

  FETCH cur INTO v;

  SELECT v;

END; 

$$

DELIMITER $$;

The same crash happens with an implicit CURSOR in a FOR loop:

DELIMITER $$

BEGIN NOT ATOMIC

DECLARE v INT DEFAULT 0;

FOR a IN (VALUES (7)) DO SET v = v + 1; END FOR;

SELECT v;

END; 

$$

DELIMITER $$;

10.3 d71a8855eef3

#3  <signal handler called>

#4  0x000055f2d94978d2 in st_select_lex_unit::get_column_types (this=0x7f8fec023d20, for_cursor=true) at /data/src/10.3/sql/sql_union.cc:1877

#5  0x000055f2d9356e2a in Select_materialize::send_result_set_metadata (this=0x7f8fec027d18, list=..., flags=5) at /data/src/10.3/sql/sql_cursor.cc:443

#6  0x000055f2d9492928 in select_union_direct::send_result_set_metadata (this=0x7f8fec027ea0, list=..., flags=5) at /data/src/10.3/sql/sql_union.cc:538

#7  0x000055f2d95a503d in table_value_constr::exec (this=0x7f8fec020e78, sl=0x7f8fec024498) at /data/src/10.3/sql/sql_tvc.cc:345

#8  0x000055f2d949613b in st_select_lex_unit::exec (this=0x7f8fec023d20) at /data/src/10.3/sql/sql_union.cc:1430

#9  0x000055f2d9491362 in mysql_union (thd=0x7f8fec000b00, lex=0x7f8fec023c58, result=0x7f8fec027d18, unit=0x7f8fec023d20, setup_tables_done_option=0) at /data/src/10.3/sql/sql_union.cc:41

#10 0x000055f2d93e2d31 in handle_select (thd=0x7f8fec000b00, lex=0x7f8fec023c58, result=0x7f8fec027d18, setup_tables_done_option=0) at /data/src/10.3/sql/sql_select.cc:360

#11 0x000055f2d93ae2e3 in execute_sqlcom_select (thd=0x7f8fec000b00, all_tables=0x0) at /data/src/10.3/sql/sql_parse.cc:6539

#12 0x000055f2d93a4a44 in mysql_execute_command (thd=0x7f8fec000b00) at /data/src/10.3/sql/sql_parse.cc:3768

#13 0x000055f2d935604c in mysql_open_cursor (thd=0x7f8fec000b00, result=0x7f8fec0161b0, pcursor=0x7f8fec0161e8) at /data/src/10.3/sql/sql_cursor.cc:145

#14 0x000055f2d92e4bf8 in sp_cursor::open (this=0x7f8fec0161a8, thd=0x7f8fec000b00) at /data/src/10.3/sql/sp_rcontext.cc:772

#15 0x000055f2d92d6653 in sp_instr_copen::exec_core (this=0x7f8fec020f38, thd=0x7f8fec000b00, nextp=0x7f90593329bc) at /data/src/10.3/sql/sp_head.cc:4283

#16 0x000055f2d92d3e98 in sp_lex_keeper::reset_lex_and_exec_core (this=0x7f8fec020f00, thd=0x7f8fec000b00, nextp=0x7f90593329bc, open_tables=false, instr=0x7f8fec020f38) at /data/src/10.3/sql/sp_head.cc:3311

#17 0x000055f2d92d4266 in sp_lex_keeper::cursor_reset_lex_and_exec_core (this=0x7f8fec020f00, thd=0x7f8fec000b00, nextp=0x7f90593329bc, open_tables=false, instr=0x7f8fec020f38) at /data/src/10.3/sql/sp_head.cc:3410

#18 0x000055f2d92d65ce in sp_instr_copen::execute (this=0x7f8fec020f38, thd=0x7f8fec000b00, nextp=0x7f90593329bc) at /data/src/10.3/sql/sp_head.cc:4272

#19 0x000055f2d92ce405 in sp_head::execute (this=0x7f8fec01fb58, thd=0x7f8fec000b00, merge_da_on_success=true) at /data/src/10.3/sql/sp_head.cc:1349

#20 0x000055f2d92d0daa in sp_head::execute_procedure (this=0x7f8fec01fb58, thd=0x7f8fec000b00, args=0x7f8fec0056e0) at /data/src/10.3/sql/sp_head.cc:2287

#21 0x000055f2d93a240b in do_execute_sp (thd=0x7f8fec000b00, sp=0x7f8fec01fb58) at /data/src/10.3/sql/sql_parse.cc:2944

#22 0x000055f2d93abc6a in mysql_execute_command (thd=0x7f8fec000b00) at /data/src/10.3/sql/sql_parse.cc:5894

#23 0x000055f2d93b1cf4 in mysql_parse (thd=0x7f8fec000b00, rawbuf=0x7f8fec013888 "BEGIN NOT ATOMIC\n  DECLARE v INT;\n  DECLARE cur CURSOR FOR VALUES(7);\n  OPEN cur;\n  FETCH cur INTO v;\n  SELECT v;\nEND", length=117, parser_state=0x7f9059334620, is_com_multi=false, is_next_command=false) at /data/src/10.3/sql/sql_parse.cc:8001

#24 0x000055f2d939f4d7 in dispatch_command (command=COM_QUERY, thd=0x7f8fec000b00, packet=0x7f8fec01bab1 "BEGIN NOT ATOMIC\n  DECLARE v INT;\n  DECLARE cur CURSOR FOR VALUES(7);\n  OPEN cur;\n  FETCH cur INTO v;\n  SELECT v;\nEND;", packet_length=118, is_com_multi=false, is_next_command=false) at /data/src/10.3/sql/sql_parse.cc:1846

#25 0x000055f2d939df16 in do_command (thd=0x7f8fec000b00) at /data/src/10.3/sql/sql_parse.cc:1391

#26 0x000055f2d9500a13 in do_handle_one_connection (connect=0x55f2dcd89fb0) at /data/src/10.3/sql/sql_connect.cc:1402

#27 0x000055f2d95007a0 in handle_one_connection (arg=0x55f2dcd89fb0) at /data/src/10.3/sql/sql_connect.cc:1308

#28 0x00007f905e492494 in start_thread (arg=0x7f9059335700) at pthread_create.c:333

#29 0x00007f905c87893f in clone () from /lib/x86_64-linux-gnu/libc.so.6