public inbox for [email protected]  

help / color / mirror / Atom feed

From: Michael Paquier <[email protected]>
To: Tom Lane <[email protected]>
Cc: [email protected]
Subject: Re: Our ABI diff infrastructure ignores enum SysCacheIdentifier
Date: Fri, 13 Feb 2026 13:07:00 +0900
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>

On Thu, Feb 12, 2026 at 11:17:37AM -0500, Tom Lane wrote:
> I discovered $SUBJECT while working on commits dbb09fd8e et al.
> The point of those commits was to back-patch addition of a syscache
> that previously existed only in v18+, so naturally I was concerned
> about not breaking ABI by changing any existing syscache's ID.
> I tested whether abidiff would bleat about it if I intentionally
> changed an ID, and found that *it didn't*.

Well.  That's annoying.  This one is important to be careful about.

> As for SysCacheIdentifier, the root of the problem is that
> SearchSysCache and friends are declared to take "int cacheId"
> not "enum SysCacheIdentifier cacheId".  Likely we should change
> that in HEAD, but that'd be an actual not theoretical ABI break
> (the enum's not necessarily int-width).

Enforcing a type for this sounds like a good idea in the long term on
HEAD, yes, even putting the ABI argument aside for a moment.  I'd
suggest the addition of an extra typedef in the code generated for 
syscache_ids.h to save from a couple of enum markers in these
declarations, once refactored to use the new enum type.

> In the back branches
> I'm thinking about adding a dummy function just for this purpose,
> more or less as in the under-commented patch attached.
> 
> Thoughts?

Adding a comment explaining why this function needs to exist would be
good.
--
Michael


Attachments:

  [application/pgp-signature] signature.asc (833B, 2-signature.asc)
  download

view thread (10+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected], [email protected]
  Subject: Re: Our ABI diff infrastructure ignores enum SysCacheIdentifier
  In-Reply-To: <[email protected]>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox