ASAN READ of size 1 in append_identifier

=================================================================

==23130==ERROR: AddressSanitizer: unknown-crash on address 0x62b00013ba82 at pc 0x5571cd2b1e3c bp 0x7fdfc59d3390 sp 0x7fdfc59d3380

READ of size 1 at 0x62b00013ba82 thread T41

    #0 0x5571cd2b1e3b in append_identifier(THD*, String*, char const*, unsigned long) /home/travis/src/sql/sql_show.cc:1642

    #1 0x5571cd87eff9 in append_identifier /home/travis/src/sql/sql_show.h:88

    #2 0x5571cd897c7a in Item_ident::print(String*, enum_query_type) /home/travis/src/sql/item.cc:3130

    #3 0x5571cd8b94e7 in Item_field::print(String*, enum_query_type) /home/travis/src/sql/item.cc:7578

    #4 0x5571cd881d6c in Item::print_parenthesised(String*, enum_query_type, precedence) /home/travis/src/sql/item.cc:421

    #5 0x5571cd96f92e in Item_func::print_op(String*, enum_query_type) /home/travis/src/sql/item_func.cc:620

    #6 0x5571cd9296ce in Item_bool_rowready_func2::print(String*, enum_query_type) /home/travis/src/sql/item_cmpfunc.h:515

    #7 0x5571cd881d6c in Item::print_parenthesised(String*, enum_query_type, precedence) /home/travis/src/sql/item.cc:421

    #8 0x5571cd2ff50b in Item::print_for_table_def(String*) /home/travis/src/sql/item.h:1645

    #9 0x5571cd2ffd43 in Virtual_column_info::print(String*) /home/travis/src/sql/item.h:7139

    #10 0x5571cd420081 in pack_expression /home/travis/src/sql/unireg.cc:639

    #11 0x5571cd420483 in pack_vcols /home/travis/src/sql/unireg.cc:676

    #12 0x5571cd41c8ea in build_frm_image(THD*, st_mysql_const_lex_string const*, HA_CREATE_INFO*, List<Create_field>&, unsigned int, st_key*, handler*) /home/travis/src/sql/unireg.cc:194

    #13 0x5571cd33d13d in mysql_create_frm_image(THD*, st_mysql_const_lex_string const*, st_mysql_const_lex_string const*, HA_CREATE_INFO*, Alter_info*, int, st_key**, unsigned int*, st_mysql_const_unsigned_lex_string*) /home/travis/src/sql/sql_table.cc:4703

    #14 0x5571cd33e57b in create_table_impl /home/travis/src/sql/sql_table.cc:4944

    #15 0x5571cd35a041 in mysql_alter_table(THD*, st_mysql_const_lex_string const*, st_mysql_const_lex_string const*, HA_CREATE_INFO*, TABLE_LIST*, Alter_info*, unsigned int, st_order*, bool) /home/travis/src/sql/sql_table.cc:9562

    #16 0x5571cd49b7bf in Sql_cmd_alter_table::execute(THD*) /home/travis/src/sql/sql_alter.cc:497

    #17 0x5571cd15251b in mysql_execute_command(THD*) /home/travis/src/sql/sql_parse.cc:6314

    #18 0x5571cd15cd6f in mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool) /home/travis/src/sql/sql_parse.cc:8116

    #19 0x5571cd137aea in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool) /home/travis/src/sql/sql_parse.cc:1852

    #20 0x5571cd134c82 in do_command(THD*) /home/travis/src/sql/sql_parse.cc:1397

    #21 0x5571cd48c904 in do_handle_one_connection(CONNECT*) /home/travis/src/sql/sql_connect.cc:1402

    #22 0x5571cd48c2e1 in handle_one_connection /home/travis/src/sql/sql_connect.cc:1308

    #23 0x7fdfd9b3f6b9 in start_thread (/lib/x86_64-linux-gnu/libpthread.so.0+0x76b9)

    #24 0x7fdfd8fd441c in clone (/lib/x86_64-linux-gnu/libc.so.6+0x10741c)

ASAN:SIGSEGV

==23130==AddressSanitizer: while reporting a bug found another one. Ignoring.

perl ./runall-new.pl --basedir=/home/travis/server --vardir=/home/travis/logs/vardir --duration=350 --threads=6 --seed=1547487570 --short-column-names --reporters=Backtrace,ErrorLog,Deadlock --validators=TransformerNoComparator --transformers=ExecuteAsExecuteImmediate,ExecuteAsInsertSelect,ExecuteAsUpdateDelete --redefine=conf/mariadb/alter_table.yy --redefine=conf/mariadb/instant_add.yy --redefine=conf/mariadb/modules/alter_table_columns.yy --redefine=conf/mariadb/modules/alter_table_indexes.yy --redefine=conf/mariadb/bulk_insert.yy --redefine=conf/mariadb/modules/admin.yy --redefine=conf/mariadb/modules/foreign_keys.yy -redefine=conf/mariadb/modules/locks.yy --redefine=conf/mariadb/modules/sql_mode.yy --redefine=conf/mariadb/redefine_temporary_tables.yy --redefine=conf/mariadb/versioning.yy --redefine=conf/mariadb/sequences.yy --mysqld=--log_output=FILE --mysqld=--max-statement-time=15 --mysqld=--lock-wait-timeout=10 --mysqld=--loose-innodb-lock-wait-timeout=5 --mysqld=--loose-debug_assert_on_not_freed_memory=0 --mysqld=--innodb-buffer-pool-size=2G --grammar=conf/runtime/alter_online.yy --gendata=conf/runtime/alter_online.zz --filter=/home/travis/mariadb-toolbox/travis/10.4-combo-filter-asan.ff --scenario=Restart