#!/usr/bin/env perl

use warnings;
use strict;

package a;

our $x = 1;

package main;

print "a::x = ", $a::x, "\n"; # Fine
print "a::z = ", $a::z, "\n"; # want to raise error here

##</code><code>##

Name "a::z" used only once: possible typo at ./647879.pl line 13.
a::x = 1
Use of uninitialized value in print at ./647879.pl line 13.
a::z =