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:
  relink_tables_for_multidelete(): 
   presence of implicitly used time zone tables is no longer condition for
   propagation of TABLE pointers from global table list to local table
   lists (since now global list is always created...)
sql/sql_lex.cc:
  - Added LEX::add_time_zone_tables_to_query_tables() function which adds
    implicitly used time zone tables to global table list.
  - Definition of fake_time_zone_tables_list moved to tztime.cc, since
    it is no longer used in parser.
sql/sql_lex.h:
  - Since now we add implicitly used time zone tables right at parsing
    stage, LEX::time_zone_tables_used is either zero or points to valid
    time zone tables list. Updated its description to reflect that.
  - Added LEX::add_time_zone_tables_to_query_tables() function which adds
    implicitly used time zone tables to global table list.
  - Declaration of fake_time_zone_tables_list moved to tztime.h,
    since it is no longer used in parser.
sql/sql_parse.cc:
  mysql_execute_command():
    Removed adding list of implicitly used time zone tables to global table
    list, since now we do this right at the parsing stage.
sql/sql_yacc.yy:
  Let us 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().
sql/tztime.cc:
  Moved fake_time_zone_tables_list definition from sql_lex.cc to
  tztime.cc since now it is used only for error reporting from
  my_tz_get_table_list() function.
sql/tztime.h:
  Moved fake_time_zone_tables_list declaration from sql_lex.h to
  tztime.h since now it is used only for error reporting from
  my_tz_get_table_list() function.

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