It seems I may have given Schwern a harder problem than I thought when I purchased his services to write tests for Tie::Hash::Cannabinol - it doesn't work under Perl 5.8.0.
In fact none of my tied hash modules work under Perl 5.8.0. It seems to be something to do with my use of the autotie function from Attribute::Handlers.
The output from the test program looks like this:
$ make test
/usr/bin/perl "-Iblib/lib" "-Iblib/arch" test.pl
Compilation failed in require at test.pl line 7.
BEGIN failed--compilation aborted at test.pl line 7.
not ok 1
# Looks like your test died before it could output anything.
make: *** [test_dynamic] Error 255
Hmmm... more investigation required.