Noalias trivia question

[T. William Wells]

In article <14522 at brl-adm.ARPA>, dsill at nswc-oas.arpa (Dave Sill) writes:

> You are implying that programmers can solve unsolvable problems but
> that programs cannot, which is simply not true.

Actually, you should keep your referents straight.  I might be
implying that humans can solve problems that are unsolvable by
COMPUTERS.  The truth of that is a matter of conjecture.

This of course ignores the fact that aliasing is a property of
the DESIGN of the program, not just of the program itself.  It is
entirely possible to design a program which has some particular
aliasing property which can't be found by inspecting the code.
Consider this contrived example:

	scanf("%d %d", &i, &j);
	p = &a[i];
	q = &a[j];

Can p and q point to the same object?  In the general case, yes.
However, the programmer might intend this to be in a system where
the two numbers can never be the same.  So, the noalias keyword
would add information that is not present in the program.