Fix for bug #6849 "Crash while preparing query containing const expr with

IN and CONVERT_TZ()" (with after review changes).

Now we add implicitly used time zone tables to global table list right
at the parsing stage instead of doing it later in mysql_execute_command()
or in check_prepared_statement().

No special test-case needed since this bug also manifests itself as
timezone2.test failure if one runs it with --ps-protocol option.

sql/sql_base.cc

@@ -1864,8 +1864,7 @@ bool open_and_lock_tables(THD *thd, TABLE_LIST *tables)
 
 static void relink_tables_for_multidelete(THD *thd)
 {
-  if (thd->lex->all_selects_list->next_select_in_list() ||
-      thd->lex->time_zone_tables_used)
+  if (thd->lex->all_selects_list->next_select_in_list())
   {
     for (SELECT_LEX *sl= thd->lex->all_selects_list;
 	 sl;

sql/sql_lex.cc

@@ -30,15 +30,6 @@
 */
 sys_var_long_ptr trg_new_row_fake_var(0, 0);
 
-/*
-  Fake table list object, pointer to which is used as special value for
-  st_lex::time_zone_tables_used indicating that we implicitly use time
-  zone tables in this statement but real table list was not yet created.
-  Pointer to it is also returned by my_tz_get_tables_list() as indication
-  of transient error;
-*/
-TABLE_LIST fake_time_zone_tables_list;
-
 /* Macros to look like lex */
 
 #define yyGet()		*(lex->ptr++)
@@ -1880,6 +1871,31 @@ void st_lex::first_lists_tables_same()
 }
 
 
+/*
+  Add implicitly used time zone description tables to global table list
+  (if needed).
+
+  SYNOPSYS
+    st_lex::add_time_zone_tables_to_query_tables()
+      thd - pointer to current thread context
+
+  RETURN VALUE
+   TRUE  - error
+   FALSE - success
+*/
+
+bool st_lex::add_time_zone_tables_to_query_tables(THD *thd)
+{
+  /* We should not add these tables twice */
+  if (!time_zone_tables_used)
+  {
+    time_zone_tables_used= my_tz_get_table_list(thd, &query_tables_last);
+    if (time_zone_tables_used == &fake_time_zone_tables_list)
+      return TRUE;
+  }
+  return FALSE;
+}
+
 /*
   Link table back that was unlinked with unlink_first_table()
 

sql/sql_lex.h

@@ -735,9 +735,8 @@ typedef struct st_lex
   /* Names of user variables holding parameters (in EXECUTE) */
   List<LEX_STRING> prepared_stmt_params; 
   /*
-    If points to fake_time_zone_tables_list indicates that time zone
-    tables are implicitly used by statement, also is used for holding
-    list of those tables after they are opened.
+    Points to part of global table list which contains time zone tables
+    implicitly used by the statement.
   */
   TABLE_LIST *time_zone_tables_used;
   sp_head *sphead;
@@ -802,6 +801,7 @@ typedef struct st_lex
     *(table->prev_global= query_tables_last)= table;
     query_tables_last= &table->next_global;
   }
+  bool add_time_zone_tables_to_query_tables(THD *thd);
 
   bool can_be_merged();
   bool can_use_merged();
@@ -810,7 +810,6 @@ typedef struct st_lex
   bool need_correct_ident();
 } LEX;
 
-extern TABLE_LIST fake_time_zone_tables_list;
 struct st_lex_local: public st_lex
 {
   static void *operator new(size_t size)

sql/sql_parse.cc

@@ -2114,19 +2114,6 @@ mysql_execute_command(THD *thd)
   }
 #endif /* !HAVE_REPLICATION */
 
-  if (lex->time_zone_tables_used)
-  {
-    TABLE_LIST *tmp;
-    if ((tmp= my_tz_get_table_list(thd, &lex->query_tables_last)) ==
-        &fake_time_zone_tables_list)
-    {
-      DBUG_RETURN(-1);
-    }
-    lex->time_zone_tables_used= tmp;
-    if (!all_tables)
-      all_tables= tmp;
-  }
-
   /*
     When option readonly is set deny operations which change tables.
     Except for the replication thread and the 'super' users.

sql/sql_yacc.yy

@@ -4266,7 +4266,8 @@ simple_expr:
 	  { $$= create_func_contains($3, $5); }
 	| CONVERT_TZ_SYM '(' expr ',' expr ',' expr ')'
 	  {
-	    Lex->time_zone_tables_used= &fake_time_zone_tables_list;
+            if (Lex->add_time_zone_tables_to_query_tables(YYTHD))
+              YYABORT;
 	    $$= new Item_func_convert_tz($3, $5, $7);
 	  }
 	| CURDATE optional_braces
@@ -7276,8 +7277,9 @@ internal_variable_name:
               If this is time_zone variable we should open time zone
               describing tables 
             */
-            if (tmp == &sys_time_zone)
-	      Lex->time_zone_tables_used= &fake_time_zone_tables_list;
+            if (tmp == &sys_time_zone &&
+                lex->add_time_zone_tables_to_query_tables(YYTHD))
+              YYABORT;
 	  }
 	  else
 	  {

sql/tztime.cc

@@ -1439,6 +1439,12 @@ tz_init_table_list(TABLE_LIST *tz_tabs, TABLE_LIST ***global_next_ptr)
 }
 
 
+/*
+  Fake table list object, pointer to which is returned by
+  my_tz_get_tables_list() as indication of error.
+*/
+TABLE_LIST fake_time_zone_tables_list;
+
 /*
   Create table list with time zone related tables and add it to the end
   of global table list.

sql/tztime.h

@@ -64,6 +64,7 @@ extern Time_zone * my_tz_find(const String *name, TABLE_LIST *tz_tables);
 extern my_bool     my_tz_init(THD *org_thd, const char *default_tzname, my_bool bootstrap);
 extern void        my_tz_free();
 
+extern TABLE_LIST fake_time_zone_tables_list;
 
 /*
   Check if we have pointer to the beggining of list of implictly used