$ perl -e '
    use strict;
    use warnings;

    use Test::More tests => 8;

    my $h = { b => {} };
    my ($f, $f2, $f3, $f4);

    $f = $h->{b}{c}{d} if exists($h->{b}{c}) and exists($h->{b}{c}{d});
    is_deeply( $h, { b => {} }, "no autovivification" );
    is( $f, undef, "no value assigned" );

    $f2 = $h->{b}{c}{d} if exists $h->{b}{c};
    is_deeply $h, { b => {} }, "f2: no autovivification";
    is $f2, undef, "f2: no value assigned";

    $f3 = $h->{b}{c}{d}{x}{y}{z} if
            exists $h->{b}{c}
        and exists $h->{b}{c}{d}
        and exists $h->{b}{c}{d}{x}
        and exists $h->{b}{c}{d}{x}{y};
    is_deeply $h, { b => {} }, "f3: no autovivification";
    is $f3, undef, "f3: no value assigned";

    $f4 = $h->{b}{c}{d}{x}{y}{z};
    delete $h->{b}{c};
    is_deeply $h, { b => {} }, "f4: autovivification removed";
    is $f4, undef, "f4: no value assigned";
'

##</code><code>##

$ perl -e '
    use strict;
    use warnings;

    use Test::More tests => 8;

    my $h = { b => {} };

    my $f = $h->{b}{c}{d} if exists($h->{b}{c}) and exists($h->{b}{c}{d});
    is_deeply( $h, { b => {} }, "no autovivification" );
    is( $f, undef, "no value assigned" );

    my $f2 = $h->{b}{c}{d} if exists $h->{b}{c};
    is_deeply $h, { b => {} }, "f2: no autovivification";
    is $f2, undef, "f2: no value assigned";

    my $f3 = $h->{b}{c}{d}{x}{y}{z} if
            exists $h->{b}{c}
        and exists $h->{b}{c}{d}
        and exists $h->{b}{c}{d}{x}
        and exists $h->{b}{c}{d}{x}{y};
    is_deeply $h, { b => {} }, "f3: no autovivification";
    is $f3, undef, "f3: no value assigned";

    my $f4 = $h->{b}{c}{d}{x}{y}{z};
    delete $h->{b}{c};
    is_deeply $h, { b => {} }, "f4: autovivification removed";
    is $f4, undef, "f4: no value assigned";
'

##</code><code>##

1..8
ok 1 - no autovivification
ok 2 - no value assigned
ok 3 - f2: no autovivification
ok 4 - f2: no value assigned
ok 5 - f3: no autovivification
ok 6 - f3: no value assigned
ok 7 - f4: autovivification removed
ok 8 - f4: no value assigned