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Re: [Qemu-devel] [PATCH 03/11] configure: Fix compiler warning in config

From: Eric Blake
Subject: Re: [Qemu-devel] [PATCH 03/11] configure: Fix compiler warning in config.log (integer from pointer)
Date: Sat, 17 Dec 2011 07:18:55 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111115 Thunderbird/8.0

On 12/17/2011 07:09 AM, Peter Maydell wrote:
>> Typically NULL is defined to be ((void *)0 for C
>> (that's the reason why I used a type cast, too). Only for
>> C++ it is defined without a type cast.
> The C standard permits plain "0" as a definition of NULL.

POSIX concurs with the C standard that a plain "0" can be used for
representing a null pointer, but requires that the macro NULL be defined
as ((void*)0) as a tighter requirement than C.


> We use plain 0 for a null pointer constant in various
> existing tests in configure; this is simpler and avoids
> dragging in stddef.h. I would prefer that.

I agree that configure tests should be as small as possible while still
being correct, and use of a 0 constant without a cast, rather than NULL,
is appropriate in that context.

Eric Blake   address@hidden    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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