$ perl -le " sub uniq {warn++$q;@_} print for sort uniq(1,8,4,3) "
1 at -e line 1.
2 at -e line 1.
3 at -e line 1.
4 at -e line 1.
1
8
4
3

$ perl -MO=Deparse -le " sub uniq {warn++$q;@_} print for sort uniq(1,8,4,3) "
BEGIN { $/ = "\n"; $\ = "\n"; }
sub uniq {
    warn ++$q;
    @_;
}
print $_ foreach (sort uniq 1, 8, 4, 3);
-e syntax OK