Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!cwjcc!ukma!rutgers!cmcl2!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: The world is not ready for 'volatile'
Message-ID: <9252@smoke.BRL.MIL>
Date: 2 Jan 89 02:20:50 GMT
References: <141@bms-at.UUCP> <275@twwells.uucp> <15166@mimsy.UUCP> <9236@smoke.BRL.MIL> <15171@mimsy.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 22

>[I wrote:]
>>A STORAGE CLASS by no means obviates the need for type qualifiers.

In article <15171@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes:
>I did not say that.  I said `register implies not-volatile, not-
>aliased': that `volatile register' and `aliased register' are
>nonsensical combinations.

Of course there are nonsensical expressions in ANY version of C
that are not ruled "illegal" just because they're useless.
But I thought you were trying to claim that "volatile" could have
been dispensed with and the necessary additional semantics
invested in "register", and THAT is what I dispute, because type
qualifiers can apply at any of the "levels" of a type
declaration, unlike storage class specifiers (which apply to the
identifier, in effect).  Thus
	register const int * volatile * const ptr = SOMETHING;
has a well-defined and possibly useful meaning, which would be
impossible (I think) to mimic correctly by stretching "register"
to serve as a type qualifier while not breaking existing usage
of "register".  In any case the switch from a storage class
specifier to a type qualifier would be pretty drastic!