Adjust to the changed Query_arena constructor:

main_mem_root is moved out of class Query_arena.


sql/sp_head.cc:
  Adjust to the changed Query_arena constructor. 
  main_mem_root is moved out of class Query_arena.
sql/sp_head.h:
  main_mem_root is moved out of class Query_arena: add it to class sp_head.
sql/sql_class.cc:
  main_mem_root is moved out of class Query_arena: remove
  constructors no longer relevant, remove dead code.
sql/sql_class.h:
  main_mem_root is moved out of class Query_arena.
sql/sql_prepare.cc:
  It's better to not use main_mem_root anywhere: logically, it's not
  a public member (can't fix sp_head::make_field and Item_subselect::exec
  to make it protected)
sql/sql_select.cc:
  New Cursor constructor, which avoids unneeded memory allocation
  when initializign main_mem_root.
sql/sql_select.h:
  main_mem_root is moved out of class Query_arena.

1 files changed, 2 insertions, 1 deletions

diff --git a/sql/sql_select.h b/sql/sql_select.h
index 5bec06fa36c..e5266944251 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -372,6 +372,7 @@ class JOIN :public Sql_alloc
 
 class Cursor: public Sql_alloc, public Query_arena
 {
+  MEM_ROOT main_mem_root;
   JOIN *join;
   SELECT_LEX_UNIT *unit;
 
@@ -396,7 +397,7 @@ public:
   void close();
 
   void set_unit(SELECT_LEX_UNIT *unit_arg) { unit= unit_arg; }
-  Cursor() :Query_arena(TRUE), join(0), unit(0) {}
+  Cursor(THD *thd);
   ~Cursor();
 };