That's not autovivification. if you print dumper the hash, there is still no id after the execute() call.

Nit: It's not autovivified.

my $href = {};
my $id = $href->{id};
print((%$href ? "not empty" : "empty"), "\n");

__END__
output
======
empty
[download]

Hash entries are never autovified.

Nit: Never say "never":

main->execute( $href->{id} );

sub execute {
    for( @_ ) {
        die if $_->{none};
    }
}

print keys %$href, $/;
[download]

(prints "id")

- tye        

Your example does not disprove what I said. What you wrote simplifies to

$href->{id}->{none}
[download]

A hash is being auto-vivified and a reference to it is assigned to $href->{id}. %{$href->{id}}, is being auto-vivified, NOT $href->{id}.

To be fair, I trust that he understood what autovivification is. He might have meant that, the OP's code will never autovivify hash values. His "never" was not your "never".