From: Tom Lane <tgl@sss.pgh.pa.us>
To: jian he <jian.universality@gmail.com>
cc: Pavel Stehule <pavel.stehule@gmail.com>, Christoph Berg <myon@debian.org>,
        Michael Banck <mbanck@gmx.net>,
 Tommy Pavlicek <tommypav122@gmail.com>,
        =?UTF-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilmari@ilmari.org>,
        pgsql-hackers@lists.postgresql.org
Subject: Re: Better error reporting from extension scripts (Was: Extend ALTER
 OPERATOR)
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Comments: In-reply-to jian he <jian.universality@gmail.com>
	message dated "Tue, 15 Oct 2024 15:10:32 +0800"
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Date: Wed, 16 Oct 2024 14:17:58 -0400
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jian he <jian.universality@gmail.com> writes:
> just found out the"elog(INFO, "should not reached here");" part never re=
ached.

You didn't check any of the cases we were discussing I guess?
(That is, places in gram.y that throw an error without a
parser_errposition call.)

Note that even if we fix all of those and keep them fixed, we still
couldn't assume the case is unreachable, because gram.y isn't
self-contained.  For instance, if we hit out-of-memory during raw
parsing, the OOM error out of mcxt.c isn't going to provide a syntax
error position.  I'm not too concerned about doing better than what
the patch does now (i.e. nothing) in such edge cases, but we can't
do worse.

> i guess, we don't need performance in script_error_callback,
> but in script_error_callback arrange code seperate  syntax error(raw
> parser) and other error seems good.
> please check the attached minor refactor.

I do not think that's an improvement.  It's more complicated and
less readable, and I don't see why we need to squeeze more
performance out of this error-reporting path that should never
be taken in production.

			regards, tom lane