Re: [PATCH] net/mlx: fix compile errors with ignore pedantic pragma

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

On Mon, Sep 19, 2016 at 04:26:05PM +0100, Bruce Richardson wrote:
> On Mon, Sep 19, 2016 at 04:59:59PM +0200, Adrien Mazarguil wrote:
> > Hi Bruce,
> > 
> > On Mon, Sep 19, 2016 at 03:36:54PM +0100, Bruce Richardson wrote:
> > > With recent gcc versions, e.g. gcc 6.1, compilation of mlx drivers with
> > > debug enabled produces lots of errors complaining that "pedantic" is
> > > not a warning level that can be ignored.
> > > 
> > > error: ‘-pedantic’ is not an option that controls warnings [-Werror=pragmas]
> > >  #pragma GCC diagnostic ignored "-pedantic"
> > >                                  ^~~~~~~~~~~
> > > 
> > > These errors can be removed by changing the "-pedantic" to "-Wpedantic".
> > 
> > Nice to have a workaround, I thought they did not keep the option at all.
> > However after testing:
> > 
> > - It does not seem to work with GCC 4.6 and older, they prefer -pedantic:
> >   "warning: unknown option after `#pragma GCC diagnostic' kind".
> > 
> > - GCC 4.9 (possibly 5.x as well) does not care, can use either -pedantic or
> >   -Wpedantic.
> > 
> > - GCC 6 can only supports -Wpedantic.
> > 
> > Note we're working toward removing the need for these #pragma in the first
> > place as soon as possible, however in the meantime I fear that checking the
> > GCC version is necessary.
> > 
> Depends on how old of GCC version we need to support. From the release notes
> it appears that -Wpedantic was introduced in GCC 4.8 (3 1/2 years ago).
> 
> https://gcc.gnu.org/gcc-4.8/changes.html
> 
> Do we need to support compilation on gcc versions older than this?

I'm all for upgrading so I do not really mind if we stop caring about older
GCC versions (especially considering this problem only occurs in debugging
mode which is seldom used by non-developers). The version check is necessary
if we want to keep full compatibility with at least:

- RHEL <= 6.x
- Debian <= 7.x
- Ubuntu <= 13.04

Works for me either way, thus:

Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

-- 
Adrien Mazarguil
6WIND