Ok, this is a bit odd ... it took me a few hours to figure out why this didn't work: 

my $s = do {
  # don't care about warnings.
  local *STDERR;
  open STDERR, '>', File::Spec->devnull();
  code_that_warns_deep_in_core_perl(); # and I can't figure out why
};

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The warning still showed. Yet if I ran the script as perl ./x.pl 2> /dev/null, well, it didn't show up. So no one is reopening anything, as my first guess supposed... and then I realised that it wasn't the warning (since a small test script didn't exhibit the same problem), but that I use diagnostics. It's only the diagnostics that show up. Ugh.

So, first question: does anyone else consider it a bug that the above doesn't DWIM when using diagnostics?

Second question is ... has anyone had any problems with codepage conversions causing: 

Use of uninitialized value in lc at /usr/lib/perl5/5.8.7/utf8_heavy.pl
 line 123.

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(That's the line that says: 
if (my $base = ($utf8::Canonical{$canonical} || $utf8::Canonical{ lc $
+utf8::PropertyAlias{$canonical} })) {

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) I haven't been able to pare it down, unfortunately, to a smaller working example. The idea is that I'm reading some XML files (XML::Twig), getting the text from there, and then doing some funkiness with the text to modify it based on data I get from elsewhere. I split the text using a reasonably complex regexp (for a split, anyway), and then I uc some of it. This, apparently, causes perl to go into utf8_heavy's utf8::SWASHNEW method where it tries to lc something that I don't get.

I've even tried to use Encode::decode to decode the UTF-8 from the XML file, but no change in behaviour (that I've noticed) there. Any clues would be appreciated. Meanwhile, I'm going to continue trying to pare down to a minimal-working example that gets the same error.

In reply to diagnostics, STDERR, and codepage conversions by Tanktalus

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