Message-ID: <0ef325fa06e7a1605c4e119c4ecb637c67e5fb4e.camel@j-davis.com>
Subject: Re: pgsql: Catalog changes preparing for builtin collation provider.
From: Jeff Davis <pgsql@j-davis.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Jeff Davis <jdavis@postgresql.org>, pgsql-committers@lists.postgresql.org
Date: Mon, 11 Mar 2024 12:26:55 -0700
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On Sun, 2024-03-10 at 00:05 -0500, Tom Lane wrote:
> Yeah.=C2=A0 It looks to me like it's somehow Perl-version-related.

I found it. On perl 5.16.3 on a failing instance:

   use strict;
   die '"" does not match qr// before substitution' unless '' =3D~ qr//;
   my $foo =3D ('|a|' =3D~ s/a//r);
   die '"" does not match qr// after substitution' unless '' =3D~ qr//;
   print "$foo\n";

dies with:

   "" does not match qr// after substitution at - line 4.

My commit adds a line using the s/// operator.

That's so bizarre that I have to guess that it's a perl bug. I poked
around in the perl docs to see if I'm missing something, but I didn't
find anything indicating that a substitution would have crazy side
effects. Please correct me if I'm wrong; I'm far from a perl expert.

Assuming that it is a perl bug, there are two potential workarounds:

1. Use qr/^$/ for the test rather than qr//.

2. Don't use s/// anywhere. Find another way to transform devel
versions into numbers.

Either one has the potential to leave traps for later. New tests might
either rely on s/// or expect qr// to work. I am inclined toward #1,
because if we use qr/^$/, other tests are likely to copy it and they
will be safe as well.

Though I'm still not sure what's going on with longfin.

Thoughts?

Regards,
	Jeff Davis