Assertion `dec' failed in Dec_ptr::cmp

set sql_mode='';

CREATE TABLE t1 (dc decimal(10));

INSERT INTO t1 VALUES (0000000),(NULL);

SELECT 1 FROM t1 GROUP BY 'm' <=> dc;

 10.4 befc09f00263d5375b2bb2ea0

mysqld: 10.4/sql/sql_type.h:138: int Dec_ptr::cmp(const my_decimal*) const: Assertion `dec' failed.

180814 14:12:26 [ERROR] mysqld got signal 6 ;

stdlib/abort.c:91(__GI_abort)[0x7f9b4374802a]

assert/assert.c:92(__assert_fail_base)[0x7f9b4373ebd7]

/lib/x86_64-linux-gnu/libc.so.6(+0x2dc82)[0x7f9b4373ec82]

sql/sql_type.h:139(Dec_ptr::cmp(my_decimal const*) const)[0x559548eea76a]

sql/sql_type.h:144(Dec_ptr::cmp(Dec_ptr const&) const)[0x559548eea7eb]

sql/item_cmpfunc.cc:828(Arg_comparator::compare_e_decimal())[0x55954972a099]

sql/item_cmpfunc.h:102(Arg_comparator::compare())[0x5595497627bb]

sql/item_cmpfunc.cc:1718(Item_func_equal::val_int())[0x559549734062]

sql/item.cc:6608(Item::save_int_in_field(Field*, bool))[0x5595496ef03d]

sql/sql_type.cc:3112(Type_handler_int_result::Item_save_in_field(Item*, Field*, bool) const)[0x559549422b12]

sql/item.cc:6618(Item::save_in_field(Field*, bool))[0x5595496ef219]

sql/item.h:3041(Item_result_field::save_in_result_field(bool))[0x559548e8ab6c]

sql/sql_select.cc:24220(copy_funcs(Item**, THD const*))[0x5595490edafb]

sql/sql_select.cc:20662(end_write(JOIN*, st_join_table*, bool))[0x5595490d65cd]

sql/sql_select.cc:27191(AGGR_OP::put_record(bool))[0x559549103714]

sql/sql_select.h:1017(AGGR_OP::put_record())[0x55954910f57b]

sql/sql_select.cc:18972(sub_select_postjoin_aggr(JOIN*, st_join_table*, bool))[0x5595490cac8e]

sql/sql_select.cc:19470(evaluate_join_record(JOIN*, st_join_table*, int))[0x5595490cce64]

sql/sql_select.cc:19289(sub_select(JOIN*, st_join_table*, bool))[0x5595490cc0e6]

sql/sql_select.cc:18790(do_select(JOIN*, Procedure*))[0x5595490c9f07]

sql/sql_select.cc:4076(JOIN::exec_inner())[0x55954906943b]

sql/sql_select.cc:3871(JOIN::exec())[0x559549067180]

sql/sql_select.cc:4277(mysql_select(THD*, 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*))[0x55954906a50b]

sql/sql_select.cc:382(handle_select(THD*, LEX*, select_result*, unsigned long))[0x559549044c37]

sql/sql_parse.cc:6546(execute_sqlcom_select(THD*, TABLE_LIST*))[0x559548fca861]

sql/sql_parse.cc:3768(mysql_execute_command(THD*))[0x559548fb9074]

sql/sql_parse.cc:8064(mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool))[0x559548fd2ca5]

sql/sql_parse.cc:1849(dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool))[0x559548faddcb]

sql/sql_parse.cc:1392(do_command(THD*))[0x559548faaf63]

sql/sql_connect.cc:1402(do_handle_one_connection(CONNECT*))[0x5595492fb768]

sql/sql_connect.cc:1309(handle_one_connection)[0x5595492fb145]

perfschema/pfs.cc:1864(pfs_spawn_thread)[0x55954a61e513]

/lib/x86_64-linux-gnu/libpthread.so.0(+0x76ba)[0x7f9b443836ba]

x86_64/clone.S:111(clone)[0x7f9b4381841d]