Bug#34749: Server crash when using NAME_CONST() with an aggregate function

NAME_CONST('whatever', -1) * MAX(whatever) bombed since -1 was
not seen as constant, but as FUNCTION_UNARY_MINUS(constant)
while we are at the same time pretending it was a basic const
item. This confused the aggregate handlers in exciting ways.
We now make NAME_CONST() behave more consistently.


mysql-test/r/func_misc.result:
  show that a combination of NAME_CONST('x', -y) and an aggregate
  no longer crashes the server.
mysql-test/t/func_misc.test:
  show that a combination of NAME_CONST('x', -y) and an aggregate
  no longer crashes the server.
sql/ha_ndbcluster_cond.cc:
  tell cluster about "new" function type NEG_FUNC.
  (this was previous identified as UNKNOWN_FUNC,
  so we just handle it the same way, that's all.)
sql/ha_ndbcluster_cond.h:
  tell cluster about "new" function type NEG_FUNC.
  (this was previous identified as UNKNOWN_FUNC,
  so we just handle it the same way, that's all.)
sql/item.cc:
  make NAME_CONST() transparent in that type() of
  -constant is that of constant, not that of unary
  minus (id est, FUNC_ITEM).
sql/item.h:
  Move constructor to item.cc
sql/item_func.h:
  Revert Bug#30832; we can apply the magic more narrowly
  (just for NAME_CONST() rather than all Item_func_neg).
  
  Introduce new function type "NEG_FUNC."

sql/item.cc

@@ -1207,6 +1207,22 @@ bool Item_name_const::is_null()
   return value_item->is_null();
 }
 
+
+Item_name_const::Item_name_const(Item *name_arg, Item *val):
+    value_item(val), name_item(name_arg)
+{
+  if (!(valid_args= name_item->basic_const_item() &&
+                    (value_item->basic_const_item() ||
+                     ((value_item->type() == FUNC_ITEM) &&
+                      (((Item_func *) value_item)->functype() ==
+                                                 Item_func::NEG_FUNC) &&
+                      (((Item_func *) value_item)->key_item()->type() !=
+                       FUNC_ITEM)))))
+    my_error(ER_WRONG_ARGUMENTS, MYF(0), "NAME_CONST");
+  Item::maybe_null= TRUE;
+}
+
+
 Item::Type Item_name_const::type() const
 {
   /*
@@ -1218,8 +1234,17 @@ Item::Type Item_name_const::type() const
     if (item->type() == FIELD_ITEM) 
       ((Item_field *) item)->... 
     we return NULL_ITEM in the case to avoid wrong casting.
+
+    valid_args guarantees value_item->basic_const_item(); if type is
+    FUNC_ITEM, then we have a fudged item_func_neg() on our hands
+    and return the underlying type.
   */
-  return valid_args ? value_item->type() : NULL_ITEM;
+  return valid_args ?
+             (((value_item->type() == FUNC_ITEM) &&
+               (((Item_func *) value_item)->functype() == Item_func::NEG_FUNC)) ?
+             ((Item_func *) value_item)->key_item()->type() :
+             value_item->type()) :
+           NULL_ITEM;
 }