I installed and tested this autovivification critter on my ActiveState Windows machine. Looks like it works just fine. Although I am a bit puzzled why I didn't need a "use Autovivification;" statement. However this does appear to work and in a lexical context as described in the docs. 
#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my %a; 

{
   no autovivification 'exists';
   
   if (exists ( $a{'abd'}->[0] ) )
   { print "yes \n"; } 
   
}

print Dumper \%a; 

if (exists ( $a{'abd'}->[0] ) )
   { print "yes \n"; } 
   
print Dumper \%a;

__END__
$VAR1 = {};
$VAR1 = {
          'abd' => []
        };

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In reply to Re^2: restricting values to a nested datastructure by Marshall
in thread restricting values to a nested datastructure by babp

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