Rename:

- current_arena to stmt_arena: the thread may have more than one
'current' arenas: one for runtime data, and one for the parsed 
tree of a statement. Only one of them is active at any moment.
- set_item_arena -> set_query_arena, because Item_arena was renamed to 
Query_arena a while ago
- set_n_backup_item_arena -> set_n_backup_active_arena;
the active arena is the arena thd->mem_root and thd->free_list
are currently pointing at.
- restore_backup_item_arena -> restore_active_arena (with the same
rationale)
- change_arena_if_needed -> activate_stmt_arena_if_needed; this
method sets thd->stmt_arena active if it's not done yet.


sql/item.cc:
  Rename.
sql/item_cmpfunc.cc:
  Rename.
sql/item_func.cc:
  Rename.
sql/item_subselect.cc:
  Rename.
sql/item_subselect.h:
  Remove an unused forward declaration.
sql/item_sum.h:
  Remove an unused forward declaration.
sql/mysql_priv.h:
  Remove an unused forward declaration.
sql/sp.cc:
  Rename.
sql/sp_head.cc:
  Rename.
sql/sql_base.cc:
  Rename.
sql/sql_class.cc:
  Rename.
sql/sql_class.h:
  Rename.
sql/sql_lex.cc:
  Rename.
sql/sql_parse.cc:
  Rename.
sql/sql_prepare.cc:
  Rename.
sql/sql_select.cc:
  Rename.
sql/sql_show.cc:
  Rename.
sql/sql_union.cc:
  Rename.
sql/sql_view.cc:
  Rename.
sql/table.cc:
  Rename.

1 files changed, 3 insertions, 3 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 1bbef46c0c9..3099a13e57c 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -1296,7 +1296,7 @@ bool agg_item_charsets(DTCollation &coll, const char *fname,
     In case we're in statement prepare, create conversion item
     in its memory: it will be reused on each execute.
   */
-  arena= thd->change_arena_if_needed(&backup);
+  arena= thd->activate_stmt_arena_if_needed(&backup);
 
   for (arg= args, last= args + nargs; arg < last; arg++)
   {
@@ -1342,7 +1342,7 @@ bool agg_item_charsets(DTCollation &coll, const char *fname,
     conv->fix_fields(thd, arg);
   }
   if (arena)
-    thd->restore_backup_item_arena(arena, &backup);
+    thd->restore_active_arena(arena, &backup);
   return res;
 }
 
@@ -1385,7 +1385,7 @@ Item_field::Item_field(THD *thd, Name_resolution_context *context_arg,
     structure can go away and pop up again between subsequent executions
     of a prepared statement).
   */
-  if (thd->current_arena->is_stmt_prepare_or_first_sp_execute())
+  if (thd->stmt_arena->is_stmt_prepare_or_first_sp_execute())
   {
     if (db_name)
       orig_db_name= thd->strdup(db_name);