Fix for bug #9286: SESSION/GLOBAL should be disallowed for user variables

BitKeeper/etc/logging_ok:
  Logging to logging@openlogging.org accepted

BitKeeper/etc/logging_ok

@@ -51,6 +51,7 @@ georg@lmy002.wdf.sap.corp
 gerberb@ou800.zenez.com
 gluh@gluh.(none)
 gluh@gluh.mysql.r18.ru
+gluh@mysql.com
 gordon@zero.local.lan
 greg@gcw.ath.cx
 greg@mysql.com

mysql-test/r/user_var.result

@@ -175,3 +175,7 @@ set @v1=null, @v2=1, @v3=1.1, @v4=now();
 select coercibility(@v1),coercibility(@v2),coercibility(@v3),coercibility(@v4);
 coercibility(@v1)	coercibility(@v2)	coercibility(@v3)	coercibility(@v4)
 2	2	2	2
+set session @honk=99;
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '@honk=99' at line 1
+set one_shot @honk=99;
+ERROR HY000: The SET ONE_SHOT syntax is reserved for purposes internal to the MySQL server

mysql-test/t/user_var.test

@@ -111,3 +111,11 @@ select FIELD( @var,'1it','Hit') as my_column;
 select @v, coercibility(@v);
 set @v1=null, @v2=1, @v3=1.1, @v4=now();
 select coercibility(@v1),coercibility(@v2),coercibility(@v3),coercibility(@v4);
+
+#
+# Bug #9286  SESSION/GLOBAL should be disallowed for user variables
+#
+--error 1064
+set session @honk=99;
+--error 1105
+set one_shot @honk=99;

sql/sql_yacc.yy

@@ -5360,17 +5360,26 @@ opt_option:
 	| OPTION {};
 
 option_value_list:
-	option_type option_value
-	| option_value_list ',' option_type option_value;
+        option_value_ext
+        | option_value_list ',' option_value_ext;
 
-option_type:
-	/* empty */	{}
+option_value_ext:
+        option_type_ext sys_option_value {}
+        | option_type option_value {}
+        ;
+
+option_type_ext:
+        option_type     {}
 	| GLOBAL_SYM	{ Lex->option_type= OPT_GLOBAL; }
 	| LOCAL_SYM	{ Lex->option_type= OPT_SESSION; }
 	| SESSION_SYM	{ Lex->option_type= OPT_SESSION; }
-	| ONE_SHOT_SYM	{ Lex->option_type= OPT_SESSION; Lex->one_shot_set= 1; }
 	;
 
+option_type:
+        /* empty */	{}
+        | ONE_SHOT_SYM	{ Lex->option_type= OPT_SESSION; Lex->one_shot_set= 1; }
+        ;
+
 opt_var_type:
 	/* empty */	{ $$=OPT_SESSION; }
 	| GLOBAL_SYM	{ $$=OPT_GLOBAL; }
@@ -5385,34 +5394,37 @@ opt_var_ident_type:
 	| SESSION_SYM '.'	{ $$=OPT_SESSION; }
 	;
 
+sys_option_value:
+        internal_variable_name equal set_expr_or_default
+        {
+          LEX *lex=Lex;
+          lex->var_list.push_back(new set_var(lex->option_type, $1.var,
+                                  &$1.base_name, $3));
+        }
+        | TRANSACTION_SYM ISOLATION LEVEL_SYM isolation_types
+        {
+          LEX *lex=Lex;
+          LEX_STRING tmp;
+          tmp.str=0;
+          tmp.length=0;
+          lex->var_list.push_back(new set_var(lex->option_type,
+                                              find_sys_var("tx_isolation"),
+                                              &tmp,
+                                              new Item_int((int32) $4)));
+        }
+        ;
+
 option_value:
 	'@' ident_or_text equal expr
 	{
 	  Lex->var_list.push_back(new set_var_user(new Item_func_set_user_var($2,$4)));
 	}
-	| internal_variable_name equal set_expr_or_default
-	  {
-	    LEX *lex=Lex;
-	    lex->var_list.push_back(new set_var(lex->option_type, $1.var,
-						&$1.base_name, $3));
-	  }
 	| '@' '@' opt_var_ident_type internal_variable_name equal set_expr_or_default
-	  {
-	    LEX *lex=Lex;
-	    lex->var_list.push_back(new set_var((enum_var_type) $3, $4.var,
-						&$4.base_name, $6));
-	  }
-	| TRANSACTION_SYM ISOLATION LEVEL_SYM isolation_types
-	  {
-	    LEX *lex=Lex;
-	    LEX_STRING tmp;
-	    tmp.str=0;
-	    tmp.length=0;
-	    lex->var_list.push_back(new set_var(lex->option_type,
-						find_sys_var("tx_isolation"),
-						&tmp,
-						new Item_int((int32) $4)));
-	  }
+	{
+          LEX *lex=Lex;
+          lex->var_list.push_back(new set_var((enum_var_type) $3, $4.var,
+                                  &$4.base_name, $6));
+        }
 	| charset old_or_new_charset_name_or_default
 	{
 	  THD *thd= YYTHD;