#!/usr/bin/perl -w

use strict;
use warnings;
use 5.010;

use Data::Dump qw(dump dd ddx);

ddx (1,'a', ());
ddx scalar (1,'a');
ddx scalar (1,'a', ());
my $var = (1,'a', ());
ddx $var;
__DATA__
output:
Useless use of a constant ("a") in void context at pm_empty_list.pl line 11.
Useless use of a constant ("a") in void context at pm_empty_list.pl line 12.
# pm_empty_list.pl:9: (1, "a")
# pm_empty_list.pl:10: "a"
# pm_empty_list.pl:11: undef
# pm_empty_list.pl:13: undef