Re: [PATCH] yavta: Format type errors for non x86 arches

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Tue, Sep 19, 2023 at 08:22:57PM +0000, Sakari Ailus wrote:
> Hi Ricardo,
> 
> On Tue, Sep 19, 2023 at 10:10:41PM +0200, Ricardo Ribalda wrote:
> > Hi Sakari
> > 
> > On Tue, 19 Sept 2023 at 22:07, Sakari Ailus <sakari.ailus@iki.fi> wrote:
> > >
> > > Hi Ricardo,
> > >
> > > Thanks for the patch.
> > >
> > > On Tue, Sep 19, 2023 at 04:01:23PM +0200, Ricardo Ribalda wrote:
> > > > mipsel64el, ppc64el, ia64, ppc64, sparc64 and x32 have different lenghts
> > > > for long long ints, which result in some compilation errors.
> > > >
> > > > Lets add some castings to help the compiler deal with this.
> > > >
> > > > We cannot use the Format macro constants ffrom inttypes because they
> > > > seem to not be compatible with kernel (__u64 et al) types.
> > > >
> > > > Signed-off-by: Ricardo Ribalda <ricardo@ribalda.com>
> > > > ---
> > > >  yavta.c | 35 +++++++++++++++++++++--------------
> > > >  1 file changed, 21 insertions(+), 14 deletions(-)
> > > >
> > > > diff --git a/yavta.c b/yavta.c
> > > > index d562863..bf54e4f 100644
> > > > --- a/yavta.c
> > > > +++ b/yavta.c
> > > > @@ -1313,7 +1313,8 @@ static void video_query_menu(struct device *dev,
> > > >                       printf("  %u: %.32s%s\n", menu.index, menu.name,
> > > >                              menu.index == value ? " (*)" : "");
> > > >               else
> > > > -                     printf("  %u: %lld%s\n", menu.index, menu.value,
> > > > +                     printf("  %u: %lld%s\n", menu.index,
> > >
> > > Could you instead use PRId64 for this? You can avoid casting to another
> > > type this way. Same for the other cases.
> > 
> > Already tried this:
> > 
> > @@ -1313,7 +1313,7 @@ static void video_query_menu(struct device *dev,
> >                         printf("  %u: %.32s%s\n", menu.index, menu.name,
> >                                menu.index == value ? " (*)" : "");
> >                 else
> > -                       printf("  %u: %lld%s\n", menu.index, menu.value,
> > +                       printf("  %u: %" PRId64 "%s\n", menu.index, menu.value,
> >                                menu.index == value ? " (*)" : "");
> >         };
> >  }
> > 
> > but gcc was not happy:
> > 
> > yavta.c: In function ‘video_query_menu’:
> > yavta.c:1316:11: warning: format ‘%ld’ expects argument of type ‘long
> > int’, but argument 3 has type ‘__s64’ {aka ‘long long int’}
> > [-Wformat=]
> >  1316 |    printf("  %u: %" PRId64 "%s\n", menu.index, menu.value,
> >       |           ^~~~~~~~~                            ~~~~~~~~~~
> >       |                                                    |
> >       |                                                    __s64 {aka
> > long long int}
> > In file included from yavta.c:26:
> > /usr/include/inttypes.h:57:34: note: format string is defined here
> >    57 | # define PRId64  __PRI64_PREFIX "d"
> 
> I guess I should have expected this...
> 
> I'm not sure if it'd be prettier but another option is to use the PRI*
> macros and explicitly cast to a standard type.
> 
> Using the standard types in the V4L2 header would have avoided this issue.
> I wonder if there's anything to be gained by using the kernel types.

The kernel has defined __s64 as signed int int for a long time now, on
all architectures, at least since

commit 0c79a8e29b5fcbcbfd611daf9d500cfad8370fcf
Author: Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Thu Jan 23 15:53:43 2014 -0800

    asm/types.h: Remove include/asm-generic/int-l64.h

which was merged in v3.14.

According to https://buildd.debian.org/status/package.php?p=yavta,
however, __s64 seems to be defined as long int on some platforms.

/me is puzzled

> Cc Hans, too.
> 
> > So I took the shotgun and fixed it with castings :)
> 
> :-)

-- 
Regards,

Laurent Pinchart