🚀 go-pugleaf

I recently wished for an extension of the switch statement, allowing not
only constant integral expressions but also constant pointer expressions in
case labels.  In private email, Chris Torek (torek@elf.bsdi.com)
has pointed out that it is undecideable at compile-time if two constant
pointer expressions are in fact equal.  Given

extern int a [N], b;

``a + N == &b'' is allowable; it is easy to construct
situations where this is detectable only at link time.  In this case,
the following fragment is no longer well-defined:

int *p;
switch (p) {
case a + N: ...
case &b:    ...
}

and that is the death knell of my proposal.

Konrad Schwarz