Split item->flags into base_flags and with_flags

This was done to simplify copying of with_* flags

Other things:
- Changed Flags to C++ enums, which enables gdb to print
  out bit values for the flags. This also enables compiler
  errors if one tries to manipulate a non existing bit in
  a variable.
- Added set_maybe_null() as a shortcut as setting the
  MAYBE_NULL flags was used in a LOT of places.
- Renamed PARAM flag to SP_VAR to ensure it's not confused with persistent
  statement parameters.

1 files changed, 2 insertions, 2 deletions

diff --git a/sql/sql_cte.cc b/sql/sql_cte.cc
index 6f62a38b231..aed37df9c42 100644
--- a/sql/sql_cte.cc
+++ b/sql/sql_cte.cc
@@ -993,7 +993,7 @@ With_element::process_columns_of_derived_unit(THD *thd,
     while ((item= it++, name= nm++))
     {
       item->set_name(thd, *name);
-      item->flags&= ~ITEM_FLAG_IS_AUTOGENERATED_NAME;
+      item->base_flags&= ~item_base_t::IS_AUTOGENERATED_NAME;
     }
 
     if (arena)
@@ -1036,7 +1036,7 @@ With_element::process_columns_of_derived_unit(THD *thd,
         my_error(ER_BAD_FIELD_ERROR, MYF(0), name->str, "CYCLE clause");
         return true;
       }
-      item->flags|= ITEM_FLAG_IS_IN_WITH_CYCLE;
+      item->base_flags|= item_base_t::IS_IN_WITH_CYCLE;
     }
   }
   unit->columns_are_renamed= true;