easy to miss bug (even in structured debug)

[Eric Dean Tribble <tribble>]

I occasionally worry about bugs resulting from passing NULL pointers
rather than pointers to objects.  The 'fetch' operations make this
especially easy.  I check these by considering the types {Foo *|NULL}
different from {Foo*} when I walk through the code in my mind.

Is there an anolgous scheme for structured debug?  Can we add this
stronger type-checking in xlint?

thanks,
dean