why p->member ?

[Ron Stanonik]

While explaining pointers to structures someone asked why
the -> operator was needed; ie, why couldn't the members be
referenced as p.member.  My first response was, we're talking
about pointers to structures, not structures, so a separate
operator is needed.  On second thought though, since the
compiler knows whether the variable is a pointer or structure,
why shouldn't the compiler do the "right" thing when it sees
p.member?

Could this ever be ambiguous?  That is, is there some declaration
of p such that p could be interpreted as both a structure and
a pointer to a separate structure.  I tried fiddling around
with unions, but could not produce such an object.

Does it make a lot more work for the compiler?  It doesn't
seem so, since it's already keeping track of p's type.

Thanks,

Ron Stanonik
stanonik at nprdc.arpa