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

[Andy Shevchenko <andy.shevchenko@gmail.com>]

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@gmail.com> wrote:
> >
> > On Fri, Oct 23, 2020 at 3:06 PM Andy Shevchenko
> > <andy.shevchenko@gmail.com> wrote:
> > > On Fri, Oct 23, 2020 at 2:39 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> > > > On Fri, Oct 23, 2020 at 12:24 PM Andy Shevchenko
> > > > <andy.shevchenko@gmail.com> 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