Assertion failure in make_empty_rec upon CONVERT PARTITION

--source include/have_partition.inc

CREATE TABLE t (

  f1 bit(1),

  f2 bit(1),

  f3 int,

  f4 int,

  f5 int

) ENGINE=MyISAM

 PARTITION BY LIST (f3) (

  PARTITION p0 VALUES IN (NULL,0),

  PARTITION p1 VALUES IN (1,2,3),

  PARTITION p2 DEFAULT

);

ALTER TABLE t CONVERT PARTITION p0 TO TABLE tp;

DROP TABLE IF EXISTS tp, t;

mariadbd: /data/bld/11.4-bug/sql/unireg.cc:1253: bool make_empty_rec(THD*, uchar*, uint, List<Create_field>&, uint, ulong): Assertion `data_offset == ((null_count + 7) / 8)' failed.

250728 14:32:31 [ERROR] /share8t/bld/11.4-bug/sql/mariadbd got signal 6 ;

#9  0x00007fb34c453eb2 in __GI___assert_fail (assertion=0x55bf860fd8b0 "data_offset == ((null_count + 7) / 8)", file=0x55bf860fd1d0 "/data/bld/11.4-bug/sql/unireg.cc", line=1253, function=0x55bf860fd8d8 "bool make_empty_rec(THD*, uchar*, uint, List<Create_field>&, uint, ulong)") at ./assert/assert.c:101

#10 0x000055bf8531cd53 in make_empty_rec (thd=0x7fb334000dc8, buff=0x7fb33416bfb6 "\353", table_options=8, create_fields=..., reclength=14, data_offset=2) at /data/bld/11.4-bug/sql/unireg.cc:1253

#11 0x000055bf8531a31c in build_frm_image (thd=0x7fb334000dc8, table=..., create_info=0x7fb34661b140, create_fields=..., keys=0, key_info=0x7fb334016998, db_file=0x7fb3340495a8) at /data/bld/11.4-bug/sql/unireg.cc:577

#12 0x000055bf85283508 in mysql_write_frm (lpt=0x7fb346618a80, flags=33) at /data/bld/11.4-bug/sql/sql_table.cc:818

#13 0x000055bf8518774e in fast_alter_partition_table (thd=0x7fb334000dc8, table=0x7fb334047e78, alter_info=0x7fb34661afd0, alter_ctx=0x7fb34661a270, create_info=0x7fb34661b140, table_list=0x7fb334015a68) at /data/bld/11.4-bug/sql/sql_partition.cc:7640

#14 0x000055bf852a3e20 in mysql_alter_table (thd=0x7fb334000dc8, new_db=0x7fb334005b50, new_name=0x7fb334005fb0, create_info=0x7fb34661b140, table_list=0x7fb334015a68, recreate_info=0x7fb34661af90, alter_info=0x7fb34661afd0, order_num=0, order=0x0, ignore=false, if_exists=false) at /data/bld/11.4-bug/sql/sql_table.cc:11250

#15 0x000055bf853684b7 in Sql_cmd_alter_table::execute (this=0x7fb3340161c8, thd=0x7fb334000dc8) at /data/bld/11.4-bug/sql/sql_alter.cc:701

#16 0x000055bf8516562a in mysql_execute_command (thd=0x7fb334000dc8, is_called_from_prepared_stmt=false) at /data/bld/11.4-bug/sql/sql_parse.cc:5874

#17 0x000055bf8516b912 in mysql_parse (thd=0x7fb334000dc8, rawbuf=0x7fb334015960 "ALTER TABLE t CONVERT PARTITION p0 TO TABLE tp", length=46, parser_state=0x7fb34661c370) at /data/bld/11.4-bug/sql/sql_parse.cc:7897

#18 0x000055bf85157c88 in dispatch_command (command=COM_QUERY, thd=0x7fb334000dc8, packet=0x7fb33400bd59 "ALTER TABLE t CONVERT PARTITION p0 TO TABLE tp", packet_length=46, blocking=true) at /data/bld/11.4-bug/sql/sql_parse.cc:1905

#19 0x000055bf851565e1 in do_command (thd=0x7fb334000dc8, blocking=true) at /data/bld/11.4-bug/sql/sql_parse.cc:1418

#20 0x000055bf8535bcdf in do_handle_one_connection (connect=0x55bf9c183008, put_in_cache=true) at /data/bld/11.4-bug/sql/sql_connect.cc:1408

#21 0x000055bf8535ba60 in handle_one_connection (arg=0x55bf9c0c71b8) at /data/bld/11.4-bug/sql/sql_connect.cc:1320

#22 0x000055bf858c3aba in pfs_spawn_thread (arg=0x55bf9c182b78) at /data/bld/11.4-bug/storage/perfschema/pfs.cc:2201

#23 0x00007fb34c4a81c4 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442

#24 0x00007fb34c52885c in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

commit ce293f0bf74a44bda79f93392b5b682ae50308ae

Merge: ca91bf5d2a2 e1e5bf98fae

Author: Sergei Golubchik

Date:   Sun Jul 27 15:45:18 2025 +0200

    Merge branch '10.11' into 11.4