UBSAN null pointer passed as argument 2, which is declared to never be null in my_case_bin on SELECT

CREATE TABLE t (a SET('') CHARACTER SET BINARY);

INSERT INTO t VALUES ('');

SELECT * FROM t WHERE LOWER(a)=LOWER(0);

/test/11.3_opt_san/strings/ctype-bin.c:253:3: runtime error: null pointer passed as argument 2, which is declared to never be null

    #0 0x559a6d3e4ce9 in my_case_bin /test/11.3_opt_san/strings/ctype-bin.c:253

    #1 0x559a6fd2d776 in Item_str_conv::val_str(String*) /test/11.3_opt_san/sql/item_strfunc.cc:2011

    #2 0x559a6f7ca279 in Arg_comparator::compare_string() /test/11.3_opt_san/sql/item_cmpfunc.cc:771

    #3 0x559a6f7add5b in Arg_comparator::compare() /test/11.3_opt_san/sql/item_cmpfunc.h:104

    #4 0x559a6f7add5b in Item_func_eq::val_int() /test/11.3_opt_san/sql/item_cmpfunc.cc:1780

    #5 0x559a6e13548e in evaluate_join_record /test/11.3_opt_san/sql/sql_select.cc:23587

    #6 0x559a6e18aa81 in sub_select(JOIN*, st_join_table*, bool) /test/11.3_opt_san/sql/sql_select.cc:23486

    #7 0x559a6e3668be in do_select /test/11.3_opt_san/sql/sql_select.cc:23003

    #8 0x559a6e3668be in JOIN::exec_inner() /test/11.3_opt_san/sql/sql_select.cc:4949

    #9 0x559a6e36b6a9 in JOIN::exec() /test/11.3_opt_san/sql/sql_select.cc:4726

    #10 0x559a6e358a7c 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*) /test/11.3_opt_san/sql/sql_select.cc:5257

    #11 0x559a6e35c713 in handle_select(THD*, LEX*, select_result*, unsigned long long) /test/11.3_opt_san/sql/sql_select.cc:628

    #12 0x559a6df3443f in execute_sqlcom_select /test/11.3_opt_san/sql/sql_parse.cc:6021

    #13 0x559a6df837f5 in mysql_execute_command(THD*, bool) /test/11.3_opt_san/sql/sql_parse.cc:3921

    #14 0x559a6df036a0 in mysql_parse(THD*, char*, unsigned int, Parser_state*) /test/11.3_opt_san/sql/sql_parse.cc:7743

    #15 0x559a6df5a750 in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool) /test/11.3_opt_san/sql/sql_parse.cc:1893

    #16 0x559a6df659dd in do_command(THD*, bool) /test/11.3_opt_san/sql/sql_parse.cc:1406

    #17 0x559a6e8ab81d in do_handle_one_connection(CONNECT*, bool) /test/11.3_opt_san/sql/sql_connect.cc:1445

    #18 0x559a6e8ade8c in handle_one_connection /test/11.3_opt_san/sql/sql_connect.cc:1347

    #19 0x152d15ce7608 in start_thread /build/glibc-SzIz7B/glibc-2.31/nptl/pthread_create.c:477

    #20 0x152d14f5c132 in __clone (/lib/x86_64-linux-gnu/libc.so.6+0x11f132)

Compiled with GCC >=7.5.0 (I use GCC 11.4.0) and:

    -DWITH_ASAN=ON -DWITH_ASAN_SCOPE=ON -DWITH_UBSAN=ON -DWSREP_LIB_WITH_ASAN=ON

Set before execution:

    export UBSAN_OPTIONS=print_stacktrace=1