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Re: Mark function arguments of type "Datum *" as "const Datum *" where possible

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Peter Eisentraut <peter@eisentraut.org>
Cc: Chao Li <li.evan.chao@gmail.com>, Nathan Bossart <nathandbossart@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Michael Paquier <michael@paquier.xyz>, Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-12-09T16:27:04Z
Lists: pgsql-hackers 
Hi,

On Fri, Oct 31, 2025 at 10:56:35AM +0100, Peter Eisentraut wrote:
> On 28.09.25 05:02, Chao Li wrote:
> > 
> > On Fri, Sep 26, 2025 at 11:00 PM Tom Lane <tgl@sss.pgh.pa.us
> > <mailto:tgl@sss.pgh.pa.us>> wrote:
> > 
> >     Yeah.  In particular, probably 99% of such Datum arrays also have an
> >     associated array of bool isnull flags.  IMO it makes exactly zero
> >     sense to const-ify the Datums without similar protection for their
> >     isnull flags.
> > 
> > 
> > Based on Tom's comment, I have made the scope a little broader. If a
> > function's "Datum *" parameter is changed to const, then if it has a
> > pairing "bool *isnull" parameter, I make it const as well. Also, if the
> > function has other pointer parameters that can be const, I change them
> > to const as well. See v3 attached.
> 
> I have committed this. 

FWIW, I just submitted a patch [1] that extends this approach to all pointer types.

[1]: https://www.postgresql.org/message-id/flat/aThMaTPjSeFq3qTf@ip-10-97-1-34.eu-west-3.compute.internal

Regards,

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

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  1. Mark function arguments of type "Datum *" as "const Datum *" where possible