output_is(<<'CODE', <<'OUT', "concatenation chain");
sub main() {
        @a = (2,4,8);
        print @a _ "\n";        # OK: 3
        print @a ^_ "\n";       # OK: 2\n4\n8\n
        print @a ^_ "\t" _ "\n";        # BAD: ''
        print (@a ^_ "\t");             # OK: 2\t4\t8\t
        print "next\n";
        print "--" _ (@a ^_ "\t");      # BAD: --
        print "next\n";
        print ((@a ^_ "\t") _ "\n");    # BAD: ''
        print "stop\n";
}
CODE
3
2
4
8
2       4       8
2       4       8       next
--2     4       8       next
2       4       8
stop
OUT