Re: [libgpiod][PATCH] treewide: rework struct gpiod_line_bulk

[Andy Shevchenko <andy.shevchenko@xxxxxxxxx>]

On Fri, Oct 23, 2020 at 02:44:06PM +0200, Bartosz Golaszewski wrote:
> On Fri, Oct 23, 2020 at 2:08 PM Andy Shevchenko
> <andy.shevchenko@xxxxxxxxx> wrote:
> >
> > On Fri, Oct 23, 2020 at 3:06 PM Andy Shevchenko
> > <andy.shevchenko@xxxxxxxxx> wrote:
> > > On Fri, Oct 23, 2020 at 2:39 PM Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
> > > > On Fri, Oct 23, 2020 at 12:24 PM Andy Shevchenko
> > > > <andy.shevchenko@xxxxxxxxx> wrote:
> >
> > ...
> >
> > > > Nope because gcc will scream:
> > > >
> > > > error: flexible array member in union
> > >
> > > Ah, of course. Should be
> > >   struct ... **lines;
> >
> > But it is not gonna work... we need an array here. or just one member
> >
> > struct *lines;
> >
> > bulk:
> >   lines = malloc(num_lines * sizeof(lines));
> >   xxx->lines = lines;
> >
> > single:
> >   xxx->lines = line;
> 
> The definition I used is clearer - it's explicit about using an array
> with a single member by default and can be extended as needed when
> allocating.

According to [1] it makes harder to avoid sizeof() type of calculation
mistakes for such struct.

>From my point of view extending something that has been already predefined
is not cool. But it's up to you to decide.

[1]: https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays


-- 
With Best Regards,
Andy Shevchenko