Fixed bug in SET enum_system_variable=NULL

.bzrignore

@@ -539,3 +539,4 @@ scripts/make_win_src_distribution
 libmysql/vio_priv.h
 libmysql_r/vio_priv.h
 hardcopy.0
+scripts/make_sharedlib_distribution

mysql-test/r/variables.result

@@ -244,6 +244,8 @@ set myisam_max_sort_file_size=100;
 Variable 'myisam_max_sort_file_size' is a GLOBAL variable and should be set with SET GLOBAL
 set myisam_max_extra_sort_file_size=100;
 Variable 'myisam_max_extra_sort_file_size' is a GLOBAL variable and should be set with SET GLOBAL
+set @@SQL_WARNINGS=NULL;
+Variable 'sql_warnings' can't be set to the value of 'NULL'
 set autocommit=1;
 set big_tables=1;
 select @@autocommit, @@big_tables;

mysql-test/t/variables.test

@@ -153,6 +153,8 @@ select @@global.sql_auto_is_null;
 set myisam_max_sort_file_size=100;
 --error 1229
 set myisam_max_extra_sort_file_size=100;
+--error 1231
+set @@SQL_WARNINGS=NULL;
 
 # Test setting all variables
 

sql/set_var.cc

@@ -394,9 +394,9 @@ sys_var *sys_variables[]=
   &sys_quote_show_create,
   &sys_rand_seed1,
   &sys_rand_seed2,
+  &sys_range_alloc_block_size,
   &sys_read_buff_size,
   &sys_read_rnd_buff_size,
-  &sys_range_alloc_block_size,
   &sys_rpl_recovery_rank,
   &sys_safe_updates,
   &sys_select_limit,
@@ -555,11 +555,11 @@ struct show_var_st init_vars[]= {
   {sys_query_cache_type.name, (char*) &sys_query_cache_type,        SHOW_SYS},
 #endif /* HAVE_QUERY_CACHE */
   {sys_query_prealloc_size.name, (char*) &sys_query_prealloc_size,  SHOW_SYS},
+  {sys_range_alloc_block_size.name, (char*) &sys_range_alloc_block_size,
+   SHOW_SYS},
   {sys_read_buff_size.name,   (char*) &sys_read_buff_size,	    SHOW_SYS},
   {sys_readonly.name,         (char*) &sys_readonly,                SHOW_SYS},
   {sys_read_rnd_buff_size.name,(char*) &sys_read_rnd_buff_size,	    SHOW_SYS},
-  {sys_range_alloc_block_size.name, (char*) &sys_range_alloc_block_size,
-   SHOW_SYS},
   {sys_rpl_recovery_rank.name,(char*) &sys_rpl_recovery_rank,       SHOW_SYS},
   {sys_server_id.name,	      (char*) &sys_server_id,		    SHOW_SYS},
   {sys_slave_net_timeout.name,(char*) &sys_slave_net_timeout,	    SHOW_SYS},
@@ -972,7 +972,8 @@ byte *sys_var_thd_bool::value_ptr(THD *thd, enum_var_type type)
 
 bool sys_var::check_enum(THD *thd, set_var *var, TYPELIB *enum_names)
 {
-  char buff[80], *value;
+  char buff[80];
+  const char *value;
   String str(buff,sizeof(buff)), *res;
 
   if (var->value->result_type() == STRING_RESULT)
@@ -982,7 +983,7 @@ bool sys_var::check_enum(THD *thd, set_var *var, TYPELIB *enum_names)
 		 (ulong) find_type(res->c_ptr(), enum_names, 3)-1))
 	< 0)
     {
-      value=res->c_ptr();
+      value= res ? res->c_ptr() : "NULL";
       goto err;
     }
   }