So, I punched a bare printf in Perl_ck_bitop, and while running 'make tests', I spotted the following potential problem in ext/Storable/t/integer.t, line 151 :
my $bit = ok (($copy_s1 ^ $copy1 == 0), "$process $copy1 (bitpattern)"); There should be parens around the ^ op. I don't know whether this has been fixed recently.