Re: Make foreach_ptr macro work in C++ extensions

Nathan Bossart <nathandbossart@gmail.com>

From: Nathan Bossart <nathandbossart@gmail.com>
To: Jelte Fennema-Nio <postgres@jeltef.nl>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-10-14T20:29:34Z
Lists: pgsql-hackers
On Mon, Oct 14, 2024 at 10:05:42PM +0200, Jelte Fennema-Nio wrote:
> I've been writing a C++ extension recently and it turns out that the
> foreach_ptr macro added in PG17 by one of my patches causes a
> compilation failure when used in C++. This is due to C++ its stricter
> rules around implicit casts from void pointers.

Whoops.

> Attached is a tiny patch that fixes that by adding an explicit cast to
> the macro.

Looks reasonable to me.

> I think it would be good to backpatch this to PG17 as well,
> as to not introduce some differences in the macro across versions.

I'd consider this a "low-risk" fix, which our versioning page [0] says is
acceptable for a minor release, so I'll plan on back-patching unless
someone objects.

[0] https://www.postgresql.org/support/versioning/

-- 
nathan



Commits

  1. Add type cast to foreach_internal's loop variable.