Re: fix for strict-alias warnings - Mailing list pgsql-patches

Tough words! :-)

ISTM the best thing would be to back out the patch, add -fno-strict-aliasing
for gcc, and add a TODO to fix this thoroughly.

Having -fstrict-aliasing on and ignoring the warnings doesn't seem like a
sound strategy. I think we should fix it or turn it off. The web is littered
with projects that got bizzare happenings when they turned it on without any
accompanying code changes.

I agree with Tom that my patch isn't ideal  (I thought I said as much).
Fixing it thoroughly will require some significant code changes, though. We
seem to be far too close to 7.4 release to contemplate that.

cheers

andrew


----- Original Message -----
From: "Tom Lane" <tgl@sss.pgh.pa.us>
To: "Bruce Momjian" <pgman@candle.pha.pa.us>
Cc: "Andrew Dunstan" <andrew@dunslane.net>; "PG Patches"
<pgsql-patches@postgresql.org>
Sent: Saturday, October 11, 2003 1:29 PM
Subject: Re: [PATCHES] fix for strict-alias warnings


> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > I don't have a version that does the double-cast, but I still have the
> > patch to back out and put in a new one.  Andrew's point was that we cast
> > to void * in many places, so this case is not unique.  Is that wrong?
>
> I do not like code that uses cast to void* as a substitute for casting
> to the real destination type.  I think it's a lazy substitute for
> providing the correct cast, and it renders the code more fragile because
> there is *no* possibility of the compiler detecting a problem should you
> change the source or destination datatype in a way that renders the cast
> wrong.
>
> I have not gone around and tried to fix all the places that are lazy in
> this way, but I don't want to introduce more, and for sure I don't want
> to set a precedent that we'll weaken our type checking any time gcc
> burps for ill-defined reasons.
>
> I agree completely with all of the objections you raised in your
> original comment on the patch.  In particular, I don't think we
> understand why gcc is complaining about these few places and not any of
> the thousands of other casts in our code.  Until we understand that
> difference completely, we are not "fixing a bug" by introducing void*
> casts.  I'd have to call it cargo-cult programming instead.
>
> I am perfectly content to leave the warnings in place until we have a
> satisfactory explanation.
>
> regards, tom lane
>
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