the code I think is resposible is in two parts

*print = *PRINT;
*printf = *PRINTF;
*new = *TIEHANDLE;
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those calls happen outside of any sub in the Filter::Handle package, so they cause usage of those symbols in F::H to resolve to those subs in the Filter::Handle package.

sub PRINT {
  my $self = shift;
  my $fh = *{$self->{fh}}}; # the file handle we tied in TIEHANDLE
  print $fh $self->{output}->(@_); # the sub we passed in in TIEHANDLE
}
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that print never used to call PRINT again.

I'll try to reduce it to a simple case, but it will have to wait till I get gome - it is 8:30pm here.

Never mind reducing it, the change I suspected is in fact the culprit. That *{$self->{fh}} wraps a new glob around the file handle to try to keep from recursing. This worked pre-5.8.0 when the tie magic was placed on the glob itself. As of 5.8.0, the tie magic attaches to just the handle portion of the glob, so the new wrapper glob is still using a tied handle, and the print recurses. (If you add a use warnings to Filter::Handle you will see a Deep recursion warning, just before it segfaults :)

I think a workaround could be done by saving a dup'ed handle in Filter::Handle::TIEHANDLE. Out of time for now.