If you decide Corion's excellent advice and enable warnings for your code while body of the code intact, you can suppress this warning easily.

sub test { my ( $s ) = @_;
   if ($s == 3) {
      no warnings 'exiting';  # suppress the warning for this lexical 
+scope only.
      next; 
    }
    else {
      print $s . "\n";
    }
}
[download]

My personal preference is to use something more like this:

use strict;
use warnings;

my @stuff = 1..5;

for my $s (@stuff) {
    next if is_bad_stuff($s);

    my $formatted = format_stuff($s);
    print "$formatted: passed\n";
}

sub is_bad_stuff { 
    my ( $s ) = @_;
    
    return $s == 3;
}

sub format_stuff {
    my ( $s ) = @_;

    $s = '<UNDEF>' 
    return "Formatted $s";
}
[download]

The downside of this is the extra function call. The upside is that it's (hopefully) easier to read and maintain.

I like to collect code with side-effects (like printing) into as few places as possible, so my format_stuff routine preps the data for output but does not emit it. I know this is a toy example, but the habit has served me well.