Thread

Re: Don't cast away const where possible

Bertrand Drouvot <bertranddrouvot.pg@gmail.com> — 2025-12-31T08:42:48Z

Hi,

On Mon, Dec 29, 2025 at 09:01:46AM +0000, Bertrand Drouvot wrote:
> Hi,
> 
> On Mon, Dec 22, 2025 at 12:53:03PM +0100, Peter Eisentraut wrote:
> > On 18.12.25 14:55, Bertrand Drouvot wrote:
> > > Some functions are casting away the const qualifiers from their signatures in
> > > local variables.
> > 
> > @@ -1304,8 +1304,8 @@ merge_overlapping_ranges(FmgrInfo *cmp, Oid colloid,
> >  static int
> >  compare_distances(const void *a, const void *b)
> >  {
> > -       DistanceValue *da = (DistanceValue *) a;
> > -       DistanceValue *db = (DistanceValue *) b;
> > +       const DistanceValue *da = (const DistanceValue *) a;
> > +       const DistanceValue *db = (const DistanceValue *) b;
> > 
> > I wonder if the better fix here wouldn't be to get rid of the cast. It's not
> > necessary, and without it the compiler would automatically warn about
> > qualifier mismatches.
> 
> Yeah, that looks better as it provides an extra safety check should the function
> signature change.

Out of curiosity, I searched for places where we could remove explicit casts when
assigning from void pointers (relying on implicit conversion instead), that would
lead to:

"
 157 files changed, 387 insertions(+), 388 deletions(-)
"

That's not a small patch and I think that doing this work is valuable though.

We could imagine, working on say 20 files at a time and say once per month.
That would ease the review(s) and also avoid too many rebases for patches waiting
in the commitfest.

Thoughts?

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com