Assertion `length || !scale' failed in uint my_decimal_length_to_precision(uint, uint, bool)

SELECT CASE 0 WHEN 1 THEN ( CASE 2 WHEN 3 THEN NULL END ) WHEN 4 THEN 5 END;

mysqld: /src/10.1/sql/my_decimal.h:213: uint my_decimal_length_to_precision(uint, uint, bool): Assertion `length || !scale' failed.

160228 17:50:59 [ERROR] mysqld got signal 6 ;

#7  0x00007f6f1a7a71d2 in __assert_fail () from /lib64/libc.so.6

#8  0x0000562a24b7abe8 in my_decimal_length_to_precision (length=0, scale=31, unsigned_flag=false) at /src/10.1/sql/my_decimal.h:213

#9  0x0000562a24bc85ba in Item_func_case::agg_num_lengths (this=0x7f6f10e53408, arg=0x7f6f10e53110) at /src/10.1/sql/item_cmpfunc.cc:3085

#10 0x0000562a24bc8908 in Item_func_case::fix_length_and_dec (this=0x7f6f10e53408) at /src/10.1/sql/item_cmpfunc.cc:3158

#11 0x0000562a24beef0e in Item_func::fix_fields (this=0x7f6f10e53408, thd=0x7f6f165c9330, ref=0x7f6f10e535a0) at /src/10.1/sql/item_func.cc:234

#12 0x0000562a24bc848d in Item_func_case::fix_fields (this=0x7f6f10e53408, thd=0x7f6f165c9330, ref=0x7f6f10e535a0) at /src/10.1/sql/item_cmpfunc.cc:3063

#13 0x0000562a248f30b9 in setup_fields (thd=0x7f6f165c9330, ref_pointer_array=0x7f6f10e53c90, fields=..., mark_used_columns=MARK_COLUMNS_READ, sum_func_list=0x7f6f10e53a80, allow_sum_func=true) at /src/10.1/sql/sql_base.cc:7896

#14 0x0000562a2498aaba in JOIN::prepare (this=0x7f6f10e53720, rref_pointer_array=0x7f6f165cd6c0, tables_init=0x0, wild_num=0, conds_init=0x0, og_num=0, order_init=0x0, skip_order_by=false, group_init=0x0, having_init=0x0, proc_param_init=0x0, select_lex_arg=0x7f6f165cd448, unit_arg=0x7f6f165ccd48) at /src/10.1/sql/sql_select.cc:795

#15 0x0000562a24994214 in mysql_select (thd=0x7f6f165c9330, rref_pointer_array=0x7f6f165cd6c0, tables=0x0, wild_num=0, fields=..., conds=0x0, og_num=0, order=0x0, group=0x0, having=0x0, proc_param=0x0, select_options=2147748608, result=0x7f6f10e53700, unit=0x7f6f165ccd48, select_lex=0x7f6f165cd448) at /src/10.1/sql/sql_select.cc:3429

#16 0x0000562a24989d6b in handle_select (thd=0x7f6f165c9330, lex=0x7f6f165ccc80, result=0x7f6f10e53700, setup_tables_done_option=0) at /src/10.1/sql/sql_select.cc:384

#17 0x0000562a2495a096 in execute_sqlcom_select (thd=0x7f6f165c9330, all_tables=0x0) at /src/10.1/sql/sql_parse.cc:5936

#18 0x0000562a2494fe72 in mysql_execute_command (thd=0x7f6f165c9330) at /src/10.1/sql/sql_parse.cc:2962

#19 0x0000562a2495d6de in mysql_parse (thd=0x7f6f165c9330, rawbuf=0x7f6f10e52d08 "SELECT CASE 0 WHEN 1 THEN ( CASE 2 WHEN 3 THEN NULL END ) WHEN 4 THEN 5 END", length=75, parser_state=0x7f6f1ca755e0) at /src/10.1/sql/sql_parse.cc:7336

#20 0x0000562a2494c0d9 in dispatch_command (command=COM_QUERY, thd=0x7f6f165c9330, packet=0x7f6f157c9eb1 "SELECT CASE 0 WHEN 1 THEN ( CASE 2 WHEN 3 THEN NULL END ) WHEN 4 THEN 5 END", packet_length=75) at /src/10.1/sql/sql_parse.cc:1488

#21 0x0000562a2494ae0b in do_command (thd=0x7f6f165c9330) at /src/10.1/sql/sql_parse.cc:1109

#22 0x0000562a24a80bc0 in do_handle_one_connection (thd_arg=0x7f6f165c9330) at /src/10.1/sql/sql_connect.cc:1349

#23 0x0000562a24a80924 in handle_one_connection (arg=0x7f6f165c9330) at /src/10.1/sql/sql_connect.cc:1261

#24 0x0000562a25188afa in pfs_spawn_thread (arg=0x7f6f151b0bf0) at /src/10.1/storage/perfschema/pfs.cc:1860

#25 0x00007f6f1c6f00a4 in start_thread () from /lib64/libpthread.so.0

#26 0x00007f6f1a85e04d in clone () from /lib64/libc.so.6

commit cc9cfecab78bde9376e4406bf24506e92fdaaeac

Author: Alexander Barkov <bar@mariadb.org>

Date:   Wed Sep 30 12:37:34 2015 +0400

    MDEV-8865 Wrong field type or metadata for COALESCE(signed_int_column, unsigned_int_column)

    Item_func_hybrid_field_type did not return correct field_type(), cmp_type()

    and result_type() in some cases, because cached_result_type and

    cached_field_type were set in independent pieces of the code and

    did not properly match to each other.

    Fix:

    - Removing Item_func_hybrid_result_type

    - Deriving Item_func_hybrid_field_type directly from Item_func

    - Introducing a new class Type_handler which guarantees that

      field_type(), cmp_type() and result_type() are always properly synchronized

      and using the new class in Item_func_hybrid_field_type.