Be aware. If you don't deliberately arrange the code in a weird order, it works just fine. That is, if your modules are loaded before the code that uses them, as in you have use Your::Module;, or even just ensure that the modules are compiled before the code that uses them, then the problem does not arise:

#!/usr/bin/perl
use warnings;
use strict;

package Foo;

sub new {
    return bless {},shift;
}

sub hello {
    print "hello";
}

package main;

sub new {
    print "haha";
    return;
}

my $a = new Foo;

$a->hello;

__END__
C:\test>junk2
hello
[download]

Just another example of the over-zealous promotion of a rare scenario, that by-the-by, provides clear and unambiguous diagnostics, into a "thou shalt not" that throws the baby out with the bath water. Just another justifiction.