Re: pointer arithmetics and casts

[Al Viro <viro@ftp.linux.org.uk>]

On Sat, May 26, 2007 at 04:32:47AM +0100, Derek M Jones wrote:
> This is an unsigned type, so the wrap around behavior is defined.
> But do you really want to map a small negative index into a large 
> positive one?
> 
> You probably have to use intptr_t and uintptr_t.
> 
> On the other hand if sizeof(size_t) == sizeof(type_of(tree for i))
> is an implicit cast needed?

It is not; however, on a lot of targets that doesn't really help since
the typical situation will have i smaller than p (any 64bit target with
32bit int).  So the problem of having to allocate a lot of extra nodes
remains...

FWIW, I don't think that asking which of the target's integer types is
suitable is really relevant; assuming that such type exists at all,
we can make it a parameter of target and be done with that (BTW, we
are not guaranteed that there is an integer type capable of holding
a pointer - see 7.18.1.4, it's an optional type).