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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mark Dilger <mark.dilger@enterprisedb.com>
cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Assert triggered during RE_compile_and_cache
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Comments: In-reply-to Mark Dilger <mark.dilger@enterprisedb.com>
	message dated "Sun, 08 Aug 2021 11:02:03 -0700"
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Date: Sun, 08 Aug 2021 14:44:02 -0400
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Mark Dilger <mark.dilger@enterprisedb.com> writes:
> There are a few changes which appear correct to me, but I don't know if =
you expected them:

>  select regexp_match('hko', '((((?<!.))))(.(\3)(\1.))');
> - regexp_match =

> ---------------
> - =

> +    regexp_match    =

> +--------------------
> + {"","","",hk,"",k}
>  (1 row)

Yes, this one is a consequence of 4aea704a5 (Fix semantics of regular
expression back-references).  The lookbehind constraint should not be
applied within the back-ref.

>  select 'nigqvigqvee' !~ '(())((\2)\2)(?:([^\W]))';
> -ERROR:  invalid regular expression: invalid escape \ sequence
> + ?column? =

> +----------
> + f
> +(1 row)
> +

and this one of 2a0af7fe4 (Allow complemented character class escapes
within regex brackets).

>  select regexp_replace('tl', '.{0}?(((?<![^][^]{1}?)))(.)\2{6}?', 'jx', =
'mt');
>   regexp_replace
>  ----------------
> - tl
> + jxl
>  (1 row)

This looks like also a consequence of 4aea704a5.

			regards, tom lane