I like to commit the following changes to <sys/tree.h>.  The primary
changes is to add a bit of const poisoning and to make the comparision
routine return long instead of int.  On a LP64 platform, the current
use of int makes doing (note the additional const poisoning)
int
cmp(const struct type *a, const struct type *b)
{
   return b->f - a->f;
}
impossible if f is wider than an int.  That's an unneeded complication.

The other thing is adding a const to the SPLAY_FIND function since that
element is read-only.  However, my problem with SPLAY_FIND is that takes
an element rather than a key type.  That could be fixed by using two
comparision routines, one for comparing struct and one to compare
a element and a key type.  Right now I work around that by moving the
key item to the beginning of the struct and casting.  But that's evil.

-- 
Matt Thomas                     email: matt@3am-software.com
3am Software Foundry              www: http://3am-software.com/bio/matt/
Cupertino, CA              disclaimer: I avow all knowledge of this 
message.