From: Richard Earnshaw <rearnsha@arm.com>
To: Bill Currie <bcurrie@tssc.co.nz>
Cc: rearnsha@sun52.arm.com
Subject: Re: suggest parentheses around assignment used as truth value
Date: Thu, 02 Jul 1998 07:08:00 -0000 [thread overview]
Message-ID: <199807021119.MAA19946@sun52.NIS.cambridge> (raw)
In-Reply-To: <359B0985.2FB4@tssc.co.nz>
> Richard Earnshaw wrote:
> > if ((x = p()) != 0) {...}
> >
> > Then it becomes clear why the extra parentheses are needed.
>
> Yes, because without the parentheses, it will be evaluated as:
>
> if (x = (p() != 0)) {...}
>
> And you're right back where you started from with a `suggest parentheses
> around assignment used as truth value' warning.
>
Of course the parentheses are necessary in that case, but the meaning is
obvious, and the compiler can tell that a warning is unnecessary.
In my opinion, it's a bug if gcc doesn't emit a warning for
if ((x = p())) {...}
but does for
if (x = p()) {...}
since apart from an extra set of parentheses they are identical. Perhaps
the warning should be changed to "suggest explicit comparison of
assignment used as truth value".
Richard.
next prev parent reply other threads:[~1998-07-02 7:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-06-30 19:49 Marc Rouaix
1998-07-01 2:51 ` Andreas Schwab
1998-07-01 9:20 ` Richard Earnshaw
1998-07-01 21:20 ` Bill Currie
1998-07-02 7:08 ` Richard Earnshaw [this message]
1998-07-03 3:31 ` Nathan Sidwell
1998-07-03 6:15 ` Richard Earnshaw
1998-07-01 3:42 ` Branko Cibej
1998-07-02 7:08 ` Carlo Wood
1998-07-03 14:48 ` Kamil Iskra
1998-07-01 4:00 Brad M. Garcia
1998-07-01 20:20 ` Tim Hollebeek
1998-07-02 1:39 ` Harvey J. Stein
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