use utf8;
use charnames ':full';

# don't use Foo;

print "Hello world \N{EURO SIGN} \n";

# no error message

##</code><code>##

use utf8;
use charnames ':full';

use Foo;

print "Hello world \N{EURO SIGN} $Foo::LN \n";

# "unreferenced scalar" message shows up, but so do both 
# intended characters (assuming you have the right font...)