no autovivification;

##</code><code>##

no autovivification qw( fetch exists delete );

##</code><code>##

$_ = uc($_) for @a;

##</code><code>##

no autovivification qw( fetch exists delete store );

##</code><code>##

$ perl -e'
   use Data::Dumper;

   {
      no autovivification qw( fetch exists delete );
      my $h;
      for (@{ $h->{k} }) { }
      print(Dumper($h));
   }

   {
      no autovivification qw( fetch exists delete store );
      my $h;
      for (@{ $h->{k} }) { }
      print(Dumper($h));
   }
'
$VAR1 = {
          'k' => []
        };
Can't vivify reference at a.pl line 14.