Noalias trivia question

[Doug Gwyn]

In article <1164 at maccs.UUCP> gordan at maccs.UUCP () writes:
>So, like, who on X3J11 will admit to having voted for (or worse,
>proposed) noalias in the first place?  Why did it seem like a good idea
>at the time, and what were the reasons for dropping it (apart from
>universal opprobrium).  Enquiring minds &c.

Unofficially speaking...

"noalias" was worked out by a special task force at the December X3J11
meeting (originally without that particular name, just as the concept)
as a compromise position that could be supported by two opposed sides
of the optimization vs. aliasing battle.  On the first day of that
meeting, in a non-binding "straw vote" it was decided to change the
semantics of "const" (which admittedly were not all that clear) from
meaning "readonly" to meaning "really constant", in fact to allocate
the eventual "const noalias" semantics to just "const".  AT&T and some
others adamantly opposed this.  The task force determined that really
this was another instance of overloading semantics onto a keyword, and
that there were three, not two, orthogonal qualifiers needed to cover
all the useful cases via multiplexing of qualifiers.  Thus the third
qualifier, eventually named "noalias".

In April, we basically had a choice between fixing "noalias" (we did
fix "const"), removing "noalias" and making "const" mean what had been
decided on December-Monday, or removing "noalias" and leaving "const"
with its "readonly" meaning.  The latter approach was adopted as the
most acceptable at this stage, although the second approach might have
been adopted had we not gone through the "noalias" detour.  Certainly
having Dennis Ritchie participating in the April-Monday discussion
helped clarify the issues and shape our final decision.  I think we
will be able to support the latest position against further onslaughts,
even though we have now left the optimizers without a handle for
performing the optimizations they sought in standard-conforming C.

Removing *all* qualifiers, as suggested in a public comment by Rob
Pike, found little support and not even Dennis was asking for that.