#! perl -slw
use strict;
my $deliberate_error='';

my $i;

length $deliberate_error;

$i;
__END__
D:\Perl\test>test
Useless use of length in void context at D:\Perl\test\test.pl8 line 7.
Useless use of private variable in void context at D:\Perl\test\test.pl8 line 9.