BUG#29030 (DROP USER command that errors still gets written to binary log

and replicated):

A DROP USER statement with a non-existing user was correctly written to
the binary log (there might be users that were removed, but not all),
but the error code was not set, which caused the slave to stop with an
error.

The error reporting code was moved to before the statement was logged
to ensure that the error information for the thread was correctly set
up. This works since my_error() will set the fields net.last_errno and
net.last_error for the thread that is reporting the error, and this
will then be picked up when the Query_log_event is created and written
to the binary log.

mysql-test/r/rpl_grant.result

+stop slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+reset master;
+reset slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+start slave;
+**** On Master ****
+CREATE USER dummy@localhost;
+CREATE USER dummy1@localhost, dummy2@localhost;
+SELECT user, host FROM mysql.user;
+user	host
+root	127.0.0.1
+dummy	localhost
+dummy1	localhost
+dummy2	localhost
+root	localhost
+root	romeo.kindahl.net
+**** On Slave ****
+SELECT user,host FROM mysql.user;
+user	host
+root	127.0.0.1
+dummy	localhost
+dummy1	localhost
+dummy2	localhost
+root	localhost
+root	romeo.kindahl.net
+**** On Master ****
+DROP USER nonexisting@localhost;
+ERROR HY000: Operation DROP USER failed for 'nonexisting'@'localhost'
+DROP USER nonexisting@localhost, dummy@localhost;
+ERROR HY000: Operation DROP USER failed for 'nonexisting'@'localhost'
+DROP USER dummy1@localhost, dummy2@localhost;
+SELECT user, host FROM mysql.user;
+user	host
+root	127.0.0.1
+root	localhost
+root	romeo.kindahl.net
+**** On Slave ****
+SELECT user,host FROM mysql.user;
+user	host
+root	127.0.0.1
+root	localhost
+root	romeo.kindahl.net
+SHOW SLAVE STATUS;
+Slave_IO_State	#
+Master_Host	127.0.0.1
+Master_User	root
+Master_Port	MASTER_PORT
+Connect_Retry	1
+Master_Log_File	master-bin.000001
+Read_Master_Log_Pos	609
+Relay_Log_File	#
+Relay_Log_Pos	#
+Relay_Master_Log_File	master-bin.000001
+Slave_IO_Running	Yes
+Slave_SQL_Running	Yes
+Replicate_Do_DB	
+Replicate_Ignore_DB	
+Replicate_Do_Table	
+Replicate_Ignore_Table	
+Replicate_Wild_Do_Table	
+Replicate_Wild_Ignore_Table	
+Last_Errno	0
+Last_Error	
+Skip_Counter	0
+Exec_Master_Log_Pos	609
+Relay_Log_Space	#
+Until_Condition	None
+Until_Log_File	
+Until_Log_Pos	0
+Master_SSL_Allowed	No
+Master_SSL_CA_File	
+Master_SSL_CA_Path	
+Master_SSL_Cert	
+Master_SSL_Cipher	
+Master_SSL_Key	
+Seconds_Behind_Master	#

mysql-test/t/rpl_grant.test

+# Tests of grants and users
+
+source include/master-slave.inc;
+source include/not_embedded.inc;
+
+--echo **** On Master ****
+connection master;
+
+CREATE USER dummy@localhost;
+CREATE USER dummy1@localhost, dummy2@localhost;
+
+SELECT user, host FROM mysql.user;
+sync_slave_with_master;
+--echo **** On Slave ****
+SELECT user,host FROM mysql.user;
+
+--echo **** On Master ****
+connection master;
+
+# No user exists
+error ER_CANNOT_USER;
+DROP USER nonexisting@localhost;
+
+# At least one user exists, but not all
+error ER_CANNOT_USER;
+DROP USER nonexisting@localhost, dummy@localhost;
+
+# All users exist
+DROP USER dummy1@localhost, dummy2@localhost;
+
+SELECT user, host FROM mysql.user;
+sync_slave_with_master;
+--echo **** On Slave ****
+SELECT user,host FROM mysql.user;
+
+--replace_result $MASTER_MYPORT MASTER_PORT
+--replace_column 1 # 8 # 9 # 23 # 33 #
+query_vertical SHOW SLAVE STATUS;

sql/sql_acl.cc

@@ -5378,6 +5378,12 @@ bool mysql_drop_user(THD *thd, List <LEX_USER> &list)
 
   VOID(pthread_mutex_unlock(&acl_cache->lock));
 
+  if (result)
+    my_error(ER_CANNOT_USER, MYF(0), "DROP USER", wrong_users.c_ptr_safe());
+
+  DBUG_PRINT("info", ("thd->net.last_errno: %d", thd->net.last_errno));
+  DBUG_PRINT("info", ("thd->net.last_error: %s", thd->net.last_error));
+
   if (mysql_bin_log.is_open())
   {
     Query_log_event qinfo(thd, thd->query, thd->query_length, 0, FALSE);
@@ -5386,8 +5392,6 @@ bool mysql_drop_user(THD *thd, List <LEX_USER> &list)
 
   rw_unlock(&LOCK_grant);
   close_thread_tables(thd);
-  if (result)
-    my_error(ER_CANNOT_USER, MYF(0), "DROP USER", wrong_users.c_ptr_safe());
   DBUG_RETURN(result);
 }