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Re: [Qemu-devel] [PATCH v2] libvixl: a64: Skip "-Wunused-variable" for g
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v2] libvixl: a64: Skip "-Wunused-variable" for gcc 5.0.0 or higher |
Date: |
Mon, 13 Oct 2014 08:59:46 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.1 |
On 10/12/2014 01:50 AM, Peter Maydell wrote:
> On 12 October 2014 01:32, Chen Gang <address@hidden> wrote:
>> On 10/12/14 5:25, Peter Maydell wrote:
>>> Some other approaches to this that would confine the
>>> fix to the makefiles rather than requiring us to modify
>>> the vixl source itself:
>>> a) add a -Wno- option for the affected .o files
>>
>> It is one way, but may have effect with gcc 4 version, and also it is
>> effect with the whole file which is wider than current way.
>>
>>> b) use -isystem rather than -I to include the libvixl
>>> directory on the include path
>>>
>>
>> It sounds good to me, although for me, it is not related with current
>> issue.
>
> -isystem disables a bunch of gcc warnings automatically,
> which is why I suggested it. I'm not overall sure it's
> a great idea though.
-isystem is a heavy hammer, affecting the entire compilation. Better
might be just marking the ONE header as being a system header (silence
various warnings caused by just that header, while still letting the
rest of the compilation warn). If the header comes from third-party
sources, this is probably the best approach. It is done by adding:
#if __GNUC__ >= 3
#pragma GCC system_header
#endif
to the header that would otherwise trigger warnings.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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