From: Tom Lane <tgl@sss.pgh.pa.us>
To: awatkins1966@gmail.com
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18995: Building with GCC 14 fails: incompatible pointer
 struct pam_message
In-reply-to: <1313566.1753280855@sss.pgh.pa.us>
References: <18995-82058da9ab4337a7@postgresql.org>
 <1313566.1753280855@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Wed, 23 Jul 2025 10:27:35 -0400"
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Date: Wed, 23 Jul 2025 10:44:06 -0400
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I wrote:
> This doesn't look like a GCC version problem, but like a discrepancy
> in the PAM header files, to wit, "const" or not in the expected
> signature of pam_passwd_conv_proc.  Can you verify whether or not
> pam_appl.h and its subsidiary headers changed?

I had a feeling we'd seen this before, and after digging in the
archives indeed we have:

https://www.postgresql.org/message-id/flat/16415.1184285944%40sss.pgh.pa.u=
s#a0a2fac693665cc517f761e24f222574

So I take back the guess that it's not about GCC version.  What
seems more likely now is that it's been a warning right along,
which you have been ignoring, and GCC 14 has decided to promote
it to an error.

We could perhaps install a configure check to see if this argument
is expected to be const or not.  But given the shortage of reports,
I think it'd be sufficient to do what I suggested in that 2007
thread:

>> The main issue in my mind would be how to determine whether to use
>> const or not.  If all Solaris releases are like this, and can be
>> expected to stay that way, I'd be inclined to just put a "#define
>> PAM_CONV_PROC_NOT_CONST" in include/port/solaris.h and drive the
>> function declaration off that.

As a short-term workaround, GCC has probably got a command-line
option to knock the error back down to a warning.

			regards, tom lane