Re: [PATCH] avoid AltiVec keyword vector

From: Thomas Monjalon <thomas@monjalon.net>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: dev@dpdk.org, David Christensen <drc@linux.vnet.ibm.com>,
	Beilei Xing <beilei.xing@intel.com>,
	Matan Azrad <matan@nvidia.com>,
	Viacheslav Ovsiienko <viacheslavo@nvidia.com>,
	Maxime Coquelin <maxime.coquelin@redhat.com>,
	Chenbo Xia <chenbo.xia@intel.com>,
	Vladimir Medvedkin <vladimir.medvedkin@intel.com>
Subject: Re: [PATCH] avoid AltiVec keyword vector
Date: Tue, 03 May 2022 17:44:26 +0200	[thread overview]
Message-ID: <4591093.jE0xQCEvom@thomas> (raw)
In-Reply-To: <YnEgUSJ77f7+RR4u@bricha3-MOBL.ger.corp.intel.com>

03/05/2022 14:30, Bruce Richardson:
> On Tue, May 03, 2022 at 02:03:21PM +0200, Thomas Monjalon wrote:
> > The keyword "vector" may conflict easily.
> > As a rule, it is better to use the alternative keyword "__vector".

I forgot to say that we should #undef vector.

> hi Thomas,
> 
> could you perhaps clarify a bit more in the log, I'm not aware of it being
> a keyword generally.

https://www.ibm.com/docs/fr/xl-c-and-cpp-linux/latest?topic=support-vector-types

> What would "vector" conflict with?
> If it's a keyword is it possible to use it as a variable name in these files?

It conflicts with anything named as "vector"
if you include AltiVec header file.
It is especially a problem when using C++ vector type,
that's why the keyword vector is not defined with C++:
https://github.com/gcc-mirror/gcc/blob/master/gcc/config/rs6000/altivec.h#L45

The workaround is to #undef vector after including altivec.h,
or directly in rte_altivec.h (with a compatibility breakage).
In any case we should use only __vector keyword to allow such #undef.