Bug #74695 Asser tion `args[0]->fixed' failed | sig 6 abort in sql/item_strfunc.h:882
Submitted: 5 Nov 2014 5:25 Modified: 31 May 2015 11:06
Reporter: Ramesh Sivaraman Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: DML Severity:S3 (Non-critical)
Version:5.6.20-debug, 5.6.22, 5.7.6 OS:Linux (CentOS 7)
Assigned to: CPU Architecture:Any

[5 Nov 2014 5:25] Ramesh Sivaraman 
Description:
mysqld: /ssd/ramesh/mysql-server/mysql-5.6/sql/item_strfunc.h:882: Item_func_conv_charset::Item_func_conv_charset(Item*, const CHARSET_INFO*, bool): Asser
tion `args[0]->fixed' failed.
05:18:51 UTC - mysqld got signal 6 ;

*** GDB info

#0  0x00007fd036fb9771 in pthread_kill () from /lib64/libpthread.so.0
#1  0x0000000000a9035e in my_write_core (sig=6) at /ssd/ramesh/mysql-server/mysql-5.6/mysys/stacktrace.c:422
#2  0x0000000000723688 in handle_fatal_signal (sig=6) at /ssd/ramesh/mysql-server/mysql-5.6/sql/signal_handler.cc:230
#3  <signal handler called>
#4  0x00007fd035dc55c9 in raise () from /lib64/libc.so.6
#5  0x00007fd035dc6cd8 in abort () from /lib64/libc.so.6
#6  0x00007fd035dbe536 in __assert_fail_base () from /lib64/libc.so.6
#7  0x00007fd035dbe5e2 in __assert_fail () from /lib64/libc.so.6
#8  0x000000000066b6e2 in Item_func_conv_charset::Item_func_conv_charset (this=0x7fcf9a87ff00, a=0x7fcf9a87fde8, cs=0x172aa00 <my_charset_utf16_czech_uca_
ci>, cache_if_const=true) at /ssd/ramesh/mysql-server/mysql-5.6/sql/item_strfunc.h:882
#9  0x000000000064c9af in Item::safe_charset_converter (this=0x7fcf9a87fde8, tocs=0x172aa00 <my_charset_utf16_czech_uca_ci>) at /ssd/ramesh/mysql-server/m
ysql-5.6/sql/item.cc:1059
#10 0x0000000000650329 in agg_item_set_converter (coll=..., fname=0xec60c4 "=", args=0x7fcf9a820428, nargs=2, flags=7, item_sep=1) at /ssd/ramesh/mysql-se
rver/mysql-5.6/sql/item.cc:2305
#11 0x0000000000650589 in agg_item_charsets (coll=..., fname=0xec60c4 "=", args=0x7fcf9a820428, nargs=2, flags=7, item_sep=1) at /ssd/ramesh/mysql-server/
mysql-5.6/sql/item.cc:2385
#12 0x0000000000683f86 in agg_item_charsets_for_comparison (c=..., name=0xec60c4 "=", items=0x7fcf9a820428, nitems=2, item_sep=1) at /ssd/ramesh/mysql-server/mysql-5.6/sql/item.h:2045
#13 0x0000000000684468 in Item_func::agg_arg_charsets_for_comparison (this=0x7fcf9a820388, c=..., items=0x7fcf9a820428, nitems=2, item_sep=1) at /ssd/ramesh/mysql-server/mysql-5.6/sql/item_func.h:206
#14 0x000000000067073b in Item_bool_func2::fix_length_and_dec (this=0x7fcf9a820388) at /ssd/ramesh/mysql-server/mysql-5.6/sql/item_cmpfunc.cc:563
#15 0x00000000006a2734 in Item_func::fix_fields (this=0x7fcf9a820388, thd=0x7fcfa3b24000, ref=0x7fcf9a87fc00) at /ssd/ramesh/mysql-server/mysql-5.6/sql/item_func.cc:231
#16 0x000000000076f599 in setup_conds (thd=0x7fcfa3b24000, tables=0x7fcf9a81fbe0, leaves=0x7fcf9a81fbe0, conds=0x7fcf9a87fc00) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_base.cc:8844
#17 0x00000000007f8b3f in setup_without_group (thd=0x7fcfa3b24000, ref_pointer_array=..., tables=0x7fcf9a81fbe0, leaves=0x7fcf9a81fbe0, fields=..., all_fields=..., conds=0x7fcf9a87fc00, order=0x0, group=0x0, hidden_group_field_count=0x7fcf9a87fae4, hidden_order_field_count=0x7fd0375af63c) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_resolver.cc:952
#18 0x00000000007f664b in JOIN::prepare (this=0x7fcf9a87f8c0, tables_init=0x7fcf9a81fbe0, wild_num=0, conds_init=0x7fcf9a820388, og_num=0, order_init=0x0, group_init=0x0, having_init=0x0, select_lex_arg=0x7fcf9a81f128, unit_arg=0x7fcf9a81f438) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_resolver.cc:177
#19 0x000000000092ff3e in subselect_single_select_engine::prepare (this=0x7fcf9a820640) at /ssd/ramesh/mysql-server/mysql-5.6/sql/item_subselect.cc:2640
#20 0x0000000000928cc4 in Item_subselect::fix_fields (this=0x7fcf9a820520, thd=0x7fcfa3b24000, ref=0x7fcf9a820688) at /ssd/ramesh/mysql-server/mysql-5.6/sql/item_subselect.cc:381
#21 0x000000000076dfc2 in setup_fields (thd=0x7fcfa3b24000, ref_pointer_array=..., fields=..., mark_used_columns=MARK_COLUMNS_READ, sum_func_list=0x7fcf9a87f448, allow_sum_func=true) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_base.cc:8303
#22 0x00000000007f654c in JOIN::prepare (this=0x7fcf9a87f200, tables_init=0x7fcf9a820a58, wild_num=0, conds_init=0x0, og_num=1, order_init=0x0, group_init=0x7fcf9a87f118, having_init=0x0, select_lex_arg=0x7fcfa3b26878, unit_arg=0x7fcfa3b26230) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_resolver.cc:168
#23 0x00000000007fe013 in mysql_prepare_select (thd=0x7fcfa3b24000, tables=0x7fcf9a820a58, wild_num=0, fields=..., conds=0x0, og_num=1, order=0x0, group=0x7fcf9a87f118, having=0x0, select_options=2147748608, result=0x7fcf9a820fd8, unit=0x7fcfa3b26230, select_lex=0x7fcfa3b26878, free_join=0x7fd0375afc37) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_select.cc:1054
#24 0x00000000007fe2ed in mysql_select (thd=0x7fcfa3b24000, tables=0x7fcf9a820a58, wild_num=0, fields=..., conds=0x0, order=0x7fcfa3b26a40, group=0x7fcfa3b26978, having=0x0, select_options=2147748608, result=0x7fcf9a820fd8, unit=0x7fcfa3b26230, select_lex=0x7fcfa3b26878) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_select.cc:1177
#25 0x00000000007fc4c7 in handle_select (thd=0x7fcfa3b24000, result=0x7fcf9a820fd8, setup_tables_done_option=0) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_select.cc:110
#26 0x00000000007d681b in execute_sqlcom_select (thd=0x7fcfa3b24000, all_tables=0x7fcf9a820a58) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_parse.cc:5103
#27 0x00000000007cf5cb in mysql_execute_command (thd=0x7fcfa3b24000) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_parse.cc:2649
#28 0x00000000007d8fa4 in mysql_parse (thd=0x7fcfa3b24000, rawbuf=0x7fcf9a81f010 "SELECT(SELECT t2.a FROM t2 WHERE t2.a=t1.a)aa,b,COUNT(b) FROM t1 GROUP BY aa", length=76, parser_state=0x7fd0375b0e70) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_parse.cc:6245
#29 0x00000000007cc557 in dispatch_command (command=COM_QUERY, thd=0x7fcfa3b24000, packet=0x7fcfa3b62001 "SELECT(SELECT t2.a FROM t2 WHERE t2.a=t1.a)aa,b,COUNT(b) FROM t1 GROUP BY aa", packet_length=76) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_parse.cc:1332
#30 0x00000000007cb646 in do_command (thd=0x7fcfa3b24000) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_parse.cc:1034
#31 0x0000000000793a61 in do_handle_one_connection (thd_arg=0x7fcfa3b24000) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_connect.cc:982
#32 0x000000000079354a in handle_one_connection (arg=0x7fcfa3b24000) at /ssd/ramesh/mysql-server/mysql-5.6/sql/sql_connect.cc:898
#33 0x0000000000ad4b5c in pfs_spawn_thread (arg=0x7fd0333feb00) at /ssd/ramesh/mysql-server/mysql-5.6/storage/perfschema/pfs.cc:1860
#34 0x00007fd036fb4df3 in start_thread () from /lib64/libpthread.so.0
#35 0x00007fd035e8601d in clone () from /lib64/libc.so.6

How to repeat:
DROP DATABASE test;CREATE DATABASE test;USE test;
CREATE TABLE t1(a CHAR(1));
ALTER TABLE t1 MODIFY a CHAR(1)CHARACTER SET utf16 COLLATE utf16_czech_ci;
create temporary table t2 SELECT * from t1;
CREATE TEMPORARY TABLE t1(a char(1));
SELECT(SELECT t2.a FROM t2 WHERE t2.a=t1.a)aa,b,COUNT(b) FROM t1 GROUP BY aa;
[5 Nov 2014 6:01] MySQL Verification Team 
Hello Ramesh Sivaraman,

Thank you for the bug report and test case.
Confirmed that only debug builds are affected - 5.6.22/5.7.6.

Thanks,
Umesh
[5 Nov 2014 6:01] MySQL Verification Team 
// 5.6.22 - debug build

(gdb) bt
#0  0x0000003deb00c8ac in pthread_kill () from /lib64/libpthread.so.0
#1  0x0000000000b0011b in my_write_core (sig=6) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/mysys/stacktrace.c:422
#2  0x000000000077ecb8 in handle_fatal_signal (sig=6) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/signal_handler.cc:230
#3  <signal handler called>
#4  0x0000003deac32625 in raise () from /lib64/libc.so.6
#5  0x0000003deac33e05 in abort () from /lib64/libc.so.6
#6  0x0000003deac2b74e in __assert_fail_base () from /lib64/libc.so.6
#7  0x0000003deac2b810 in __assert_fail () from /lib64/libc.so.6
#8  0x00000000006c3d0a in Item_func_conv_charset::Item_func_conv_charset (this=0x7f665c05ad70, a=0x7f665c05ac58, cs=0x18af2a0, cache_if_const=true)
    at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/item_strfunc.h:882
#9  0x00000000006a466e in Item::safe_charset_converter (this=0x7f665c05ac58, tocs=0x18af2a0) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/item.cc:1059
#10 0x00000000006a808f in agg_item_set_converter (coll=..., fname=0xff2034 "=", args=0x7f665c0063e8, nargs=2, flags=7, item_sep=1)
    at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/item.cc:2321
#11 0x00000000006a8311 in agg_item_charsets (coll=..., fname=0xff2034 "=", args=0x7f665c0063e8, nargs=2, flags=7, item_sep=1)
    at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/item.cc:2401
#12 0x00000000006dcbdb in agg_item_charsets_for_comparison (c=..., name=0xff2034 "=", items=0x7f665c0063e8, nitems=2, item_sep=1)
    at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/item.h:2045
#13 0x00000000006dd0de in Item_func::agg_arg_charsets_for_comparison (this=0x7f665c006348, c=..., items=0x7f665c0063e8, nitems=2, item_sep=1)
    at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/item_func.h:206
#14 0x00000000006c8e6f in Item_bool_func2::fix_length_and_dec (this=0x7f665c006348) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/item_cmpfunc.cc:561
#15 0x00000000006fc70a in Item_func::fix_fields (this=0x7f665c006348, thd=0x4056bf0, ref=0x7f665c05aa70) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/item_func.cc:231
#16 0x00000000007cc6b5 in setup_conds (thd=0x4056bf0, tables=0x7f665c005ba0, leaves=0x7f665c005ba0, conds=0x7f665c05aa70)
    at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_base.cc:8864
#17 0x0000000000858263 in setup_without_group (thd=0x4056bf0, ref_pointer_array=..., tables=0x7f665c005ba0, leaves=0x7f665c005ba0, fields=..., all_fields=..., conds=0x7f665c05aa70, order=0x0,
    group=0x0, hidden_group_field_count=0x7f665c05a954, hidden_order_field_count=0x7f66935c78bc) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_resolver.cc:952
#18 0x0000000000855c9c in JOIN::prepare (this=0x7f665c05a730, tables_init=0x7f665c005ba0, wild_num=0, conds_init=0x7f665c006348, og_num=0, order_init=0x0, group_init=0x0, having_init=0x0,
    select_lex_arg=0x7f665c0050e8, unit_arg=0x7f665c0053f8) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_resolver.cc:173
#19 0x000000000099741e in subselect_single_select_engine::prepare (this=0x7f665c006600) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/item_subselect.cc:2631
#20 0x000000000098fd8b in Item_subselect::fix_fields (this=0x7f665c0064e0, thd=0x4056bf0, ref=0x7f665c006648)
    at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/item_subselect.cc:381
#21 0x00000000007cb09a in setup_fields (thd=0x4056bf0, ref_pointer_array=..., fields=..., mark_used_columns=MARK_COLUMNS_READ, sum_func_list=0x7f665c05a2b8, allow_sum_func=true)
    at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_base.cc:8323
#22 0x0000000000855b9d in JOIN::prepare (this=0x7f665c05a070, tables_init=0x7f665c006a18, wild_num=0, conds_init=0x0, og_num=1, order_init=0x0, group_init=0x7f665c059f88, having_init=0x0,
    select_lex_arg=0x4059468, unit_arg=0x4058e20) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_resolver.cc:168
#23 0x000000000085d75c in mysql_prepare_select (thd=0x4056bf0, tables=0x7f665c006a18, wild_num=0, fields=..., conds=0x0, og_num=1, order=0x0, group=0x7f665c059f88, having=0x0,
    select_options=2147748608, result=0x7f665c006f98, unit=0x4058e20, select_lex=0x4059468, free_join=0x7f66935c7f1b)
    at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_select.cc:1054
#24 0x000000000085da28 in mysql_select (thd=0x4056bf0, tables=0x7f665c006a18, wild_num=0, fields=..., conds=0x0, order=0x4059630, group=0x4059568, having=0x0, select_options=2147748608,
    result=0x7f665c006f98, unit=0x4058e20, select_lex=0x4059468) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_select.cc:1177
#25 0x000000000085bb8f in handle_select (thd=0x4056bf0, result=0x7f665c006f98, setup_tables_done_option=0) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_select.cc:110
#26 0x00000000008354bc in execute_sqlcom_select (thd=0x4056bf0, all_tables=0x7f665c006a18) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_parse.cc:5103
#27 0x000000000082dc14 in mysql_execute_command (thd=0x4056bf0) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_parse.cc:2649
#28 0x00000000008380e1 in mysql_parse (thd=0x4056bf0, rawbuf=0x7f665c004fd0 "SELECT(SELECT t2.a FROM t2 WHERE t2.a=t1.a)aa,b,COUNT(b) FROM t1 GROUP BY aa", length=76,
    parser_state=0x7f66935c9680) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_parse.cc:6357
#29 0x000000000082aa63 in dispatch_command (command=COM_QUERY, thd=0x4056bf0, packet=0x4186541 "SELECT(SELECT t2.a FROM t2 WHERE t2.a=t1.a)aa,b,COUNT(b) FROM t1 GROUP BY aa", packet_length=76)
    at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_parse.cc:1332
#30 0x0000000000829ac8 in do_command (thd=0x4056bf0) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_parse.cc:1034
#31 0x00000000007f0f17 in do_handle_one_connection (thd_arg=0x4056bf0) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_connect.cc:982
#32 0x00000000007f09e8 in handle_one_connection (arg=0x4056bf0) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/sql/sql_connect.cc:898
#33 0x0000000000e64c25 in pfs_spawn_thread (arg=0x4149c70) at /pb2/build/sb_0-13562263-1414689457.82/mysqlcom-pro-5.6.22/storage/perfschema/pfs.cc:1860
#34 0x0000003deb0079d1 in start_thread () from /lib64/libpthread.so.0
#35 0x0000003deace89dd in clone () from /lib64/libc.so.6
[5 Nov 2014 6:02] MySQL Verification Team 
// 5.7.6 debug build

(gdb) bt
#0  0x0000003deb00c8ac in pthread_kill () from /lib64/libpthread.so.0
#1  0x0000000000f990a1 in my_write_core (sig=6) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/mysys/stacktrace.c:247
#2  0x000000000092d7cc in handle_fatal_signal (sig=6) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/signal_handler.cc:219
#3  <signal handler called>
#4  0x0000003deac32625 in raise () from /lib64/libc.so.6
#5  0x0000003deac33e05 in abort () from /lib64/libc.so.6
#6  0x0000003deac2b74e in __assert_fail_base () from /lib64/libc.so.6
#7  0x0000003deac2b810 in __assert_fail () from /lib64/libc.so.6
#8  0x00000000009c8562 in Item_func_conv_charset::Item_func_conv_charset (this=0x7f6dd803d4f0, a=0x7f6dd803d3d0, cs=0x20b3940, cache_if_const=true)
    at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/item_strfunc.h:1207
#9  0x00000000009a9514 in Item::safe_charset_converter (this=0x7f6dd803d3d0, tocs=0x20b3940) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/item.cc:1135
#10 0x00000000009ad009 in agg_item_set_converter (coll=..., fname=0x157279c "=", args=0x7f6dd803baf0, nargs=2, flags=7, item_sep=1)
    at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/item.cc:2396
#11 0x00000000009ad28c in agg_item_charsets (coll=..., fname=0x157279c "=", args=0x7f6dd803baf0, nargs=2, flags=7, item_sep=1)
    at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/item.cc:2476
#12 0x00000000009e32ab in agg_item_charsets_for_comparison (c=..., name=0x157279c "=", items=0x7f6dd803baf0, nitems=2, item_sep=1)
    at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/item.h:2331
#13 0x00000000009e3786 in Item_func::agg_arg_charsets_for_comparison (this=0x7f6dd803ba48, c=..., items=0x7f6dd803baf0, nitems=2, item_sep=1)
    at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/item_func.h:279
#14 0x00000000009cd6d7 in Item_bool_func2::fix_length_and_dec (this=0x7f6dd803ba48) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/item_cmpfunc.cc:594
#15 0x0000000000a0f661 in Item_func::fix_fields (this=0x7f6dd803ba48, thd=0x7f6dd8000cf0, ref=0x7f6dd8006e00)
    at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/item_func.cc:248
#16 0x0000000000ceb24d in st_select_lex::setup_conds (this=0x7f6dd8006d50, thd=0x7f6dd8000cf0) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_resolver.cc:843
#17 0x0000000000ceec4b in setup_without_group (thd=0x7f6dd8000cf0, ref_pointer_array=..., tables=0x7f6dd803b4d0, fields=..., all_fields=..., order=0x0, group=0x0,
    hidden_group_field_count=0x7f6dd803d0bc, hidden_order_field_count=0x7f6e10bb66ac) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_resolver.cc:2337
#18 0x0000000000ce92f0 in st_select_lex::prepare (this=0x7f6dd8006d50, join=0x7f6dd803cea0) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_resolver.cc:186
#19 0x0000000000ba7fca in subselect_single_select_engine::prepare (this=0x7f6dd8007388) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/item_subselect.cc:2657
#20 0x0000000000ba087d in Item_subselect::fix_fields (this=0x7f6dd803bbe8, thd=0x7f6dd8000cf0, ref=0x7f6dd8006570)
    at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/item_subselect.cc:400
#21 0x0000000000c3ffd7 in setup_fields (thd=0x7f6dd8000cf0, ref_pointer_array=..., fields=..., mark_used_columns=MARK_COLUMNS_READ, sum_func_list=0x7f6dd803c8a8, allow_sum_func=true)
    at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_base.cc:8650
#22 0x0000000000ce920d in st_select_lex::prepare (this=0x7f6dd80054f0, join=0x7f6dd803c668) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_resolver.cc:179
#23 0x0000000000cf484b in mysql_prepare_select (thd=0x7f6dd8000cf0, fields=..., select_options=2147748608, result=0x7f6dd80073f8, select_lex=0x7f6dd80054f0, free_join=0x7f6e10bb6d7e)
    at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_select.cc:947
#24 0x0000000000cf48fa in mysql_prepare_and_optimize_select (thd=0x7f6dd8000cf0, fields=..., select_options=2147748608, result=0x7f6dd80073f8, select_lex=0x7f6dd80054f0,
    free_join=0x7f6e10bb6d7e) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_select.cc:986
#25 0x0000000000cf4a84 in mysql_select (thd=0x7f6dd8000cf0, fields=..., select_options=2147748608, result=0x7f6dd80073f8, select_lex=0x7f6dd80054f0)
    at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_select.cc:1051
#26 0x0000000000cf2f6f in handle_select (thd=0x7f6dd8000cf0, result=0x7f6dd80073f8, setup_tables_done_option=0)
    at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_select.cc:97
#27 0x0000000000cbbfbc in execute_sqlcom_select (thd=0x7f6dd8000cf0, all_tables=0x7f6dd803bf28) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_parse.cc:4998
#28 0x0000000000cb4078 in mysql_execute_command (thd=0x7f6dd8000cf0) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_parse.cc:2487
#29 0x0000000000cbce6a in mysql_parse (thd=0x7f6dd8000cf0, parser_state=0x7f6e10bb8660) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_parse.cc:5397
#30 0x0000000000cb0f2c in dispatch_command (command=COM_QUERY, thd=0x7f6dd8000cf0, packet=0x7f6dd8009a21 "SELECT(SELECT t2.a FROM t2 WHERE t2.a=t1.a)aa,b,COUNT(b) FROM t1 GROUP BY aa",
    packet_length=76) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_parse.cc:1249
#31 0x0000000000cafbd4 in do_command (thd=0x7f6dd8000cf0) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/sql_parse.cc:833
#32 0x0000000000dbe89c in handle_connection (arg=0x3f85910) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/sql/conn_handler/connection_handler_per_thread.cc:298
#33 0x000000000138347f in pfs_spawn_thread (arg=0x3ddbf20) at /pb2/build/sb_0-13559856-1414670154.69/mysqlcom-pro-5.7.6-m16/storage/perfschema/pfs.cc:2137
#34 0x0000003deb0079d1 in start_thread () from /lib64/libpthread.so.0
#35 0x0000003deace89dd in clone () from /lib64/libc.so.6
[5 Nov 2014 6:32] MySQL Verification Team 
duplicate of mine:
Bug 13740934 - ASSERTION FAILED: ARGS[0]->FIXED ITEM_FUNC_CONV_CHARSET::ITEM_FUNC_CONV_CHARSET
[5 Nov 2014 6:33] MySQL Verification Team 
I had to comment out the assertion in my test setup.  This one gets hit very often (I had few thousand per night in one test) :)
[5 Nov 2014 6:49] Roel Van de Paar 
Lol :)
[31 May 2015 11:06] Erlend Dahl 
[26 May 2015 6:37] Paul Dubois

Noted in 5.7.8, 5.8.0 changelogs.

For debug builds, an assertion could be raised in character-set
conversion code due to an overly strict condition.

Under the heading of

Bug #13740934 	ASSERTION FAILED: ARGS[0]->FIXED ITEM_FUNC_CONV_CHARSET::ITEM_FUNC_CONV_CHARSET
[8 Nov 2016 7:13] Roel Van de Paar 
Would it be possible to backport this to 5.6? Thanks
[14 Aug 2017 1:50] Roel Van de Paar 
A backport to 5.6 would be appreciated, thanks!