Path: utzoo!mnetor!uunet!husc6!cmcl2!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: "Noalias" warning and questions
Message-ID: <7249@brl-smoke.ARPA>
Date: 12 Feb 88 05:46:11 GMT
References: <8012@elsie.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 19

In article <8012@elsie.UUCP> ado@elsie.UUCP (Arthur David Olson) writes:
>Since many standard library functions
>have prototypes that declare arguments to be "noalias", you'll need to
>ensure that there's no such overlap when you call them.

This is not new; in earlier working drafts this injunction was given
in English near the beginning of Section 4; now it is expressed more
directly in the function interface definitions, using "noalias".
The one hold-out is memmove(), which explicitly DOES permit overlap.

If "noalias" should disappear (a distinct possibility!), we would
have to put back the English injunction against overlapping *arguments.

As to your specific questions, I think the fair thing is to
acknowledge that there are some real problems with the whole
approach.  I don't know how thwy will be resolved.  Certainly it
must be possible to do obviously valid things with these library
functions, so if the current specification imposes silly
constraints then it will have to be fixed.