The above set of names seems to produce a suitably bad set of compile problems on a Unicode naive version of ExtUtils::Constant (ie 0.11):

nick@thinking-cap 15439-32-utf$ PERL_CORE=1 ./perl lib/ExtUtils/t/Constant.t 1..33 # perl=/stuff/perl5/15439-32-utf/perl # ext-30370 being created... Wide character in print at lib/ExtUtils/t/Constant.t line 140. ok 1 ok 2 # make = 'make' ExtTest.xs: In function `constant_1': ExtTest.xs:80: warning: multi-character character constant ExtTest.xs:80: warning: case value out of range ok 3