From: Jim Meyering <jim@meyering.net>
To: Florian Weimer <fweimer@redhat.com>
Cc: Roland McGrath <roland@hack.frob.com>,
libc-alpha <libc-alpha@sourceware.org>
Subject: Re: [PATCH] assert.h: allow gcc to detect assert(a = 1) errors
Date: Sat, 26 Nov 2016 06:15:00 -0000 [thread overview]
Message-ID: <CA+8g5KGiN54O-jV7-NEP-4a9FrP6tio0xp2J=V0x-QX4tfAz2A@mail.gmail.com> (raw)
In-Reply-To: <93a7b09e-70b9-d11e-bfb5-e54e751c8db5@redhat.com>
On Wed, Nov 23, 2016 at 11:36 PM, Florian Weimer <fweimer@redhat.com> wrote:
> On 11/24/2016 03:21 AM, Jim Meyering wrote:
>
>> We *do* need that __STRICT_ANSI__ disjunct.
>> Otherwise, this would evoke no warning:
>>
>> $ gcc -isystem. -I. -Werror=pedantic k.c
>> In file included from k.c:1:0:
>> k.c: In function ‘main’:
>> k.c:2:23: warning: ISO C forbids braced-groups within expressions
>> [-Wpedantic]
>> int main() { assert ( ({1;}) ); return 0; }
>
>
> Agreed.
>
>> Tests I ran manually in a directory with the new assert.h file:
>
>
>> Do you require a test suite addition for these? If so, would a single
>> bourne shell script be acceptable?
>
>
> We currently lack the machinery for that. It's not just that it would need
> a shell script. We also do not compile tests with headers as system
> headers.
>
> The patch looks good to me, but it needs a ChangeLog entry.
Thanks for the review.
Here's a proposed ChangeLog entry:
2016-11-25 Jim Meyering <meyering@fb.com>
Let gcc detect assert(a = 1) errors.
* assert/assert.h (assert): Rewrite assert's definition so that a
s/==/=/ typo, e.g., assert(errno = ENOENT) is not hidden from
gcc's -Wparentheses by assert-added parentheses. The new
definition uses "if (expr) /* empty */; else __assert_fail...",
so gcc -Wall will now detect that type of error in an assert, too.
The __STRICT_ANSI__ disjunct is to avoid the warning that -Wpedantic
would otherwise issue for the use of ({...}). I would have preferred
to use __extension__ to mark that, but doing so would mistakenly
suppress warnings about any extension in the user-supplied "expr".
E.g., "assert ( ({1;}) )" must continue to evoke a warning.
https://bugzilla.redhat.com/1105335
next prev parent reply other threads:[~2016-11-26 6:15 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-16 19:12 Jim Meyering
2014-07-16 20:15 ` Roland McGrath
2014-07-16 20:44 ` Jim Meyering
2016-11-24 2:22 ` Jim Meyering
2016-11-24 2:59 ` Zack Weinberg
2016-11-24 13:13 ` Joseph Myers
2016-11-26 6:36 ` Jim Meyering
2016-11-24 7:36 ` Florian Weimer
2016-11-26 6:15 ` Jim Meyering [this message]
2016-12-09 3:21 ` Jim Meyering
2016-12-14 5:28 ` Jim Meyering
2016-12-14 9:13 ` Florian Weimer
2016-12-15 0:25 ` Jim Meyering
2016-12-16 12:15 ` Florian Weimer
2016-12-18 9:53 ` Jim Meyering
2016-12-27 17:47 ` Andreas Schwab
2016-12-28 12:50 ` Florian Weimer
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