Newsgroups: comp.lang.c
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Noalias considered unreadable, let alone a bad idea
Message-ID: <1988Jan26.123817.5188@utzoo.uucp>
Organization: U of Toronto Zoology
References: <7072@brl-smoke.ARPA> <7160@brl-smoke.ARPA> <3932@hoptoad.uucp>, <7181@brl-smoke.ARPA>
Date: Tue, 26-Jan-88 12:38:14 EST

> ... most of the ones who will
> be (or are) attempting to implement the ANSI C specifications either are
> on the Committee or have sufficient contacts with Committee members who
> can answer questions about some of the subtler points.

I understand this position but don't sympathize.  If the content is complete
and unambiguous but so poorly phrased that it is necessary to consult with
a Committee member to understand it, then the document is inappropriate as
a standard.  If the content is incomplete or ambiguous, which I would say
is the case, then things get much worse.

Are the words of a Committee member to be considered official?  If not, then
we have the situation where asking different people might get different
answers -- the standard is ambiguous, pure and simple, and there is no way
for an implementor to be happy with it.  If the words ARE official, then
an individual Committee member is essentially issuing revisions to the
standard by private mail!  I don't know about ANSI, but IEEE strictly
forbids anything of the sort, on the grounds that standards are made by
a consensus process followed by open publication and revisions should be
made the same way.  (This is not just a question of preferred behavior; the
rule was made to head off major legal dangers.)  Doug, please check ANSI's
rules; I strongly suspect that this appeal to consultation with committee
members cannot be used as an official excuse.

> If you can suggest improvements in any of the wording in the proposed
> Standard, I would urge that they be sent in as comments during the next
> formal public review period, which should start soon.  It would help to
> make the final Standard as intelligible as possible.  (Even stating that
> you find some topic confusing, unclear, or ambiguous would be helpful.)

Unless a miracle happens, my formal comments during the public review will
state that "noalias" is confusing, unclear, ambiguous, and a clear case of
inappropriate invention of unproven features by the Committee, and that
the correct way to improve the wording of the proposed Standard is to
delete "noalias" completely, since there is NO simple, clear, well-proven
way of solving the admittedly-serious aliasing problem.
-- 
Those who do not understand Unix are |  Henry Spencer @ U of Toronto Zoology
condemned to reinvent it, poorly.    | {allegra,ihnp4,decvax,utai}!utzoo!henry