From: Jiri Slaby <email@example.com>
To: Tejun Heo <firstname.lastname@example.org>, Christoph Hellwig <email@example.com>
Cc: firstname.lastname@example.org, Martin Liska <email@example.com>,
Josef Bacik <firstname.lastname@example.org>, Jens Axboe <email@example.com>,
Subject: Re: [PATCH] block/blk-iocost (gcc13): cast enum members to int in prints
Date: Tue, 1 Nov 2022 06:46:56 +0100 [thread overview]
Message-ID: <firstname.lastname@example.org> (raw)
On 31. 10. 22, 18:57, Tejun Heo wrote:
> On Mon, Oct 31, 2022 at 05:24:28AM -0700, Christoph Hellwig wrote:
>> On Mon, Oct 31, 2022 at 12:45:20PM +0100, Jiri Slaby (SUSE) wrote:
>>> Cast the enum members to int when printing them.
>>> Alternatively, we can cast them to ulong (to silence gcc < 12) and use %lu.
>>> Alternatively, we can move VTIME_PER_SEC away from the enum.
>> Yes, either split the enum or just use a define. But casts are a big
>> code smell and should be avoided if there is a reasonable alternative.
> enums are so much better for debugging and other instrumentation stuff. The
> only requirement for the enum types is that they're big enough to express
> all the members and we can use whatever printf format letter which matches
> the type in use. The problem here is that the compiler behavior is different
> depending on the compiler version, which kinda sucks.
Yes. The real problem is that using anything else then an INT_MIN <= x
<= INT_MAX _constant_ in an enum is undefined in ANSI C < 2x (in
particular, 1 << x is undefined too). gcc manual defines unsigned int on
the top of that as defined too (so this holds for our -std=g*).
> I suppose the most reasonable thing to do here is just splitting them into
> separate enum definitions. Does anyone know how this behavior change came to
C2x which introduces un/signed long enums. See the bug I linked in the
The change is also turned on in < C2x on purpose. AIUI, unless there is
too much breakage. So we'd need to sort it out in (rather distant)
future anyway (when we come up to -std=g2x).
> Do we know whether clang is gonna be changed the same way?
In C2x, Likely. In < C2x, dunno what'd be the default.
next prev parent reply other threads:[~2022-11-01 5:47 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-31 11:45 [PATCH] block/blk-iocost (gcc13): cast enum members to int in prints Jiri Slaby (SUSE)
2022-10-31 12:24 ` Christoph Hellwig
2022-10-31 17:57 ` Tejun Heo
2022-11-01 5:46 ` Jiri Slaby [this message]
2022-11-01 16:46 ` Tejun Heo
2022-11-02 8:35 ` David Laight
2022-11-02 16:27 ` 'Tejun Heo'
2022-11-02 16:43 ` 'Tejun Heo'
2022-12-12 12:14 ` Jiri Slaby
2022-12-12 21:46 ` 'Tejun Heo'
2022-12-13 8:30 ` David Laight
2022-12-13 11:15 ` Jiri Slaby
2022-12-13 11:50 ` David Laight
2022-12-13 12:05 ` Jiri Slaby
2022-12-13 12:58 ` David Laight
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