#!/usr/bin/perl

use strict;
use warnings;

sub foo {
    my $sub = shift;
    local $_;
    $sub->();
}
$_ = 10;
foo (sub { print $_ });

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;

my $var = 10;
foo(sub { print $var });
sub foo {
    my $sub = shift;
    undef $var;
    $sub->(); # unitialized warning
}