Date: Wed, 20 Jan 1999 16:31:29 +0200 (SAT) From: Robert Nordier <rnordier@nordier.com> To: peter@netplex.com.au (Peter Wemm) Cc: fenner@parc.xerox.com, bde@zeta.org.au, cvs-committers@FreeBSD.ORG Subject: Re: -Werror Message-ID: <199901201431.QAA02757@ceia.nordier.com> In-Reply-To: <199901201228.UAA19912@spinner.netplex.com.au> from Peter Wemm at "Jan 20, 99 08:28:18 pm"
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Peter Wemm wrote:
> Bill Fenner wrote:
> > Or should simply be caught by --don't-be-lazy . -Werror doesn't help
> > when the committer thinks that it's so obvious and simple that there's
> > no need to even try building it.
> >
> > Bill
>
> The last time the warnings, etc, thing came up, the consensis was:
>
> In development mode, all practical warnings turned on.
> In release mode, turn them off. It's no use scaring the users about
> something they have little or no control over.
>
> Personally, I'd be quite happy to have -Werror turned on during
> development, providing that it doesn't make it into any releases.
One consequence of -Werror is that is forces a trade-off between
o the number of warnings it is practical to turn on
o the amount of rewriting of existing code it is practical to do
Particularly in the case of a compiler (versus a good-quality lint
tool), warnings have a probability of accuracy that ranges from
fairly low to extremely high.
The effect -Werror has is to force a binary choice: either take
the warning completely seriously (and rewrite any correct code that
confuses the compiler), or turn the warning off.
For example, compiled with -Wall, the code fragment
if (x = y)
x = z + 1 & 7;
causes two warnings
suggest parentheses around assignment used as truth value
suggest parentheses around + or - in operand of &
but rewriting to eliminate the errors would violate a style(9)
guideline (unnecessary parentheses). There's an awful lot of BSD
code like this, that could cause huge {Net,Open}BSD diffs if
rewritten.
So (to give just one example) if -Werror if used, -Wall becomes
problematic. And so -Werror may result in useful warnings getting
turned off rather than on.
--
Robert Nordier
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