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From: Eric Blake <eblake@redhat.com>
To: Max Reitz <mreitz@redhat.com>, Markus Armbruster <armbru@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
	qemu-devel@nongnu.org, qemu-block@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v3 2/5] qapi: Add qobject_is_equal()
Date: Wed, 5 Jul 2017 12:18:07 -0500	[thread overview]
Message-ID: <e53d0019-c9d5-5bf8-837a-12f3261a275e@redhat.com> (raw)
In-Reply-To: <fabe727c-7024-9f4b-99b3-fecb5da26acf@redhat.com>

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On 07/05/2017 12:00 PM, Max Reitz wrote:
>> (uint64_t)(UINT64_MAX + 1) is well-defined - it is 0.
>>
>> (Adding in unsigned integers is always well-defined - it wraps around on
>> mathematical overflow modulo the integer size.  You're thinking of
>> overflow addition on signed integers, which is indeed undefined)
> 
> It's not. See the standard:
> 
> When a finite value of real floating type is converted to an integer

Ah, you're talking:

(uint64_t)(double)(UINT64_MAX + 1), which is indeed undefined.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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  parent reply	other threads:[~2017-07-05 17:18 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-03 12:25 [Qemu-devel] [PATCH v3 0/5] block: Don't compare strings in bdrv_reopen_prepare() Max Reitz
2017-07-03 12:25 ` [Qemu-devel] [PATCH v3 1/5] qapi/qnull: Add own header Max Reitz
2017-07-03 12:35   ` Eric Blake
2017-07-03 12:25 ` [Qemu-devel] [PATCH v3 2/5] qapi: Add qobject_is_equal() Max Reitz
2017-07-03 12:44   ` Eric Blake
2017-07-05  7:07   ` Markus Armbruster
2017-07-05 13:48     ` Max Reitz
2017-07-05 14:15       ` Eric Blake
2017-07-05 16:11         ` Markus Armbruster
2017-07-05 16:05       ` Max Reitz
2017-07-05 16:22         ` Max Reitz
2017-07-05 16:29           ` Eric Blake
2017-07-05 17:00             ` Max Reitz
2017-07-05 17:04               ` Max Reitz
2017-07-05 17:22                 ` Eric Blake
2017-07-05 17:18               ` Eric Blake [this message]
2017-07-05 16:30           ` Max Reitz
2017-07-03 12:25 ` [Qemu-devel] [PATCH v3 3/5] block: qobject_is_equal() in bdrv_reopen_prepare() Max Reitz
2017-07-03 12:51   ` Eric Blake
2017-07-03 13:01     ` Max Reitz
2017-07-03 14:29       ` Eric Blake
2017-07-05  7:14   ` Markus Armbruster
2017-07-05 17:50     ` Max Reitz
2017-07-03 12:25 ` [Qemu-devel] [PATCH v3 4/5] iotests: Add test for non-string option reopening Max Reitz
2017-07-03 12:25 ` [Qemu-devel] [PATCH v3 5/5] tests: Add check-qobject for equality tests Max Reitz
2017-07-03 14:15   ` Eric Blake
2017-07-03 16:13     ` Max Reitz
2017-07-05  7:22   ` Markus Armbruster

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