==2976== Conditional jump or move depends on uninitialised value(s)

==2976==    at 0x5381F0: st_join_table::save_explain_data(Explain_table_access*, unsigned long long, bool, st_join_table*) (sql_show.h:205)

==2976==    by 0x539E10: JOIN::save_explain_data_intern(Explain_query*, bool, bool, bool, char const*) (sql_select.cc:23789)

==2976==    by 0x540745: JOIN::optimize() (sql_select.cc:1046)

==2976==    by 0x540882: mysql_select(THD*, Item***, TABLE_LIST*, unsigned int, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) (sql_select.cc:3306)

==2976==    by 0x543CC3: handle_select(THD*, LEX*, select_result*, unsigned long) (sql_select.cc:372)

==2976==    by 0x4EB8C4: execute_sqlcom_select(THD*, TABLE_LIST*) (sql_parse.cc:5729)

==2976==    by 0x4F248F: mysql_execute_command(THD*) (sql_parse.cc:2809)

==2976==    by 0x4FA71C: mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:7011)

==2976==    by 0x4FD811: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1469)

==2976==    by 0x4FDDA1: do_command(THD*) (sql_parse.cc:1092)

==2976==    by 0x5B2351: do_handle_one_connection(THD*) (sql_connect.cc:1394)

==2976==    by 0x5B2505: handle_one_connection (sql_connect.cc:1305)

==2976==    by 0x827102: pfs_spawn_thread (pfs.cc:1860)

==2976==    by 0x60E0E99: start_thread (pthread_create.c:308)

==2976==    by 0x69E63FC: clone (clone.S:112)

create table t1 (a int);

insert into t1 values (1), (2), (3), (4);

show columns from t1;

drop table t1;