[Mesa-dev] [PATCH 03/13] isl: Don't use designated initializers in the header

[Chad Versace]

On Tue 19 Apr 2016, Emil Velikov wrote:
> On 16 April 2016 at 20:45, Jason Ekstrand <jason at jlekstrand.net> wrote:
> > C++ doesn't support designated initializers and g++ in particular doesn't
> > handle them when the struct gets complicated, i.e. has a union.
> > ---
> >  src/intel/isl/isl.h | 32 ++++++++++++++++++++------------
> >  1 file changed, 20 insertions(+), 12 deletions(-)
> >
> > diff --git a/src/intel/isl/isl.h b/src/intel/isl/isl.h
> > index 33d43d7..c3a1106 100644
> > --- a/src/intel/isl/isl.h
> > +++ b/src/intel/isl/isl.h
> > @@ -988,25 +988,35 @@ isl_surf_info_is_z32_float(const struct isl_surf_init_info *info)
> >  static inline struct isl_extent2d
> >  isl_extent2d(uint32_t width, uint32_t height)
> >  {
> > -   return (struct isl_extent2d) { .w = width, .h = height };
> > +   struct isl_extent2d e = {
> > +      { width, },
> > +      { height, },
> > +   };
> > +   return e;
> >  }
> >
> Please use something like the following
> 
>    struct isl_extent2d e;
> 
>    memset(&e, 0, sizeof(e));
>    e.w = width;
>    e.h = height;
> 
>    return e;
> 
> It is a bit over expressive to write/look at, although it will give
> you exactly what you want _all_ the time.
> Otherwise you risk feeding garbage and/or setting the wrong struct
> member as isl_extent2d change.
> 
> Hunting bugs that this may cause, is not what you want to do. Plus the
> compiler will optimise it to the exact same code.

I agree with Emil. Let's use explicit member names when initializing the
structs. But, the memset isn't needed. The below initializaing pattern
is more concise and *safer*, as it doesn't requiring typing the struct
size.

	struct isl_extent2d e = {0};

	e.w = width;
	e.h = height;

	return e;