[Draft] MSAN errors in ftb_parse_query_internal

# Search pattern(s): (?^s:ftb_parse_query_internal)

CREATE TABLE table2_aria (col_varchar_128_utf8_fulltext_key_not_null varchar(128) CHARACTER SET utf8 not null,

col_varchar_128_latin1_fulltext_key_default_null varchar(128) CHARACTER SET latin1 default null,

col_char_255_latin1_fulltext_key char(255) CHARACTER SET latin1,

fulltext key (col_char_255_latin1_fulltext_key DESC)) ENGINE=aria;

SELECT col_varchar_128_utf8_fulltext_key_not_null,MATCH (col_varchar_128_latin1_fulltext_key_default_null) AGAINST (CONCAT(' (', ' (', 'technique', ') ', ') ') IN BOOLEAN MODE) AS SCORE FROM table2_aria WHERE MATCH (col_varchar_128_latin1_fulltext_key_default_null) AGAINST (CONCAT(' (', 'technique', '*', ') ') IN BOOLEAN MODE) ORDER BY 2 DESC;

==1614481==WARNING: MemorySanitizer: use-of-uninitialized-value

    #0 0x5587d7f927b5 in ftb_parse_query_internal /data/bld/10.6.23-msan/storage/maria/ma_ft_boolean_search.c:300:5

    #1 0x5587d7f8e9cc in _ftb_parse_query /data/bld/10.6.23-msan/storage/maria/ma_ft_boolean_search.c:331:3

    #2 0x5587d7f8e9cc in maria_ft_init_boolean_search /data/bld/10.6.23-msan/storage/maria/ma_ft_boolean_search.c:596:7

    #3 0x5587d7df3790 in ha_maria::ft_init_ext(unsigned int, unsigned int, String*) /data/bld/10.6.23-msan/storage/maria/ha_maria.cc:3476:10

    #4 0x5587d78a347c in Item_func_match::init_search(THD*, bool) /data/bld/10.6.23-msan/sql/item_func.cc:6277:28

    #5 0x5587d6cef10b in init_ftfuncs(THD*, st_select_lex*, bool) /data/bld/10.6.23-msan/sql/sql_base.cc:9229:21

    #6 0x5587d6f17631 in JOIN::optimize_stage2() /data/bld/10.6.23-msan/sql/sql_select.cc:3198:9

    #7 0x5587d6f1f042 in JOIN::optimize_inner() /data/bld/10.6.23-msan/sql/sql_select.cc:2639:9

    #8 0x5587d6f13352 in JOIN::optimize() /data/bld/10.6.23-msan/sql/sql_select.cc:1927:10

    #9 0x5587d6efb75e in mysql_select(THD*, TABLE_LIST*, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) /data/bld/10.6.23-msan/sql/sql_select.cc:5182:19

    #10 0x5587d6efb0e5 in handle_select(THD*, LEX*, select_result*, unsigned long) /data/bld/10.6.23-msan/sql/sql_select.cc:573:10

    #11 0x5587d6e7473f in execute_sqlcom_select(THD*, TABLE_LIST*) /data/bld/10.6.23-msan/sql/sql_parse.cc:6422:12

    #12 0x5587d6e5fd35 in mysql_execute_command(THD*, bool) /data/bld/10.6.23-msan/sql/sql_parse.cc:4013:12

    #13 0x5587d6e4f5c9 in mysql_parse(THD*, char*, unsigned int, Parser_state*) /data/bld/10.6.23-msan/sql/sql_parse.cc:8200:18

    #14 0x5587d6e48754 in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool) /data/bld/10.6.23-msan/sql/sql_parse.cc:1908:7

    #15 0x5587d6e50681 in do_command(THD*, bool) /data/bld/10.6.23-msan/sql/sql_parse.cc:1421:17

    #16 0x5587d7289f9c in do_handle_one_connection(CONNECT*, bool) /data/bld/10.6.23-msan/sql/sql_connect.cc:1386:11

    #17 0x5587d7289a6a in handle_one_connection /data/bld/10.6.23-msan/sql/sql_connect.cc:1298:5

    #18 0x5587d7ff2ea2 in pfs_spawn_thread /data/bld/10.6.23-msan/storage/perfschema/pfs.cc:2201:3

    #19 0x7f899ae771c3 in start_thread nptl/pthread_create.c:442:8

    #20 0x7f899aef785b in clone3 misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

  Uninitialized value was stored to memory at

    #0 0x5587d7f927ae in ftb_parse_query_internal /data/bld/10.6.23-msan/storage/maria/ma_ft_boolean_search.c:300:43

  Uninitialized value was created by an allocation of 'w' in the stack frame

    #0 0x5587d7f926e7 in ftb_parse_query_internal /data/bld/10.6.23-msan/storage/maria/ma_ft_boolean_search.c:295:3

SUMMARY: MemorySanitizer: use-of-uninitialized-value /data/bld/10.6.23-msan/storage/maria/ma_ft_boolean_search.c:300:5 in ftb_parse_query_internal