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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: pointers
Date: Wed, 26 Oct 2016 11:52:45 -0700
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BartC <bc@freeuk.com> writes:
> On 26/10/2016 17:05, Keith Thompson wrote:
>> BartC <bc@freeuk.com> writes:
>
>>> & & &***p;  // allowed on some compilers when p is T***
>
>> No doubt the inability to write & & &***p has been a great
>> inconvenience to you.
>
> What's the point of allowing &* and *&? I have an idea how that can 
> useful, but I'd be interested in hearing your take first.

What would be the point of disallowing them?  The semantics of
the "&" operator are such that it can be applied to the result
of a "*" operator, and vice versa.  Expressions are built up from
subexpressions in an arbitrary manner (subject to any constraints).
I see no reason for the language to go out of its way to impose
arbitrary restrictions.  (Nor do I see any reason for it to to out
of its way to make arbitrary nonsensical constructs valid.)

It probably doesn't make much sense to write `- - - - - - - - 0`,
but it would make even less sense for the language to go out of
its way to disallow it.  Any arbitrary restriction intended solely
to prevent you from doing something silly is likely to prevent you
from doing something useful.  And to forestall your likely response,
I do not consider the fact that the unary "&" operator does not
yield an lvalue, or that it requires an lvalue as its operand,
to be arbitrary; both rules are part of the fundamental semantics
of the operator, and are applied consistently.

[snip]

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"