use warnings;
use v5.14;

outer1();

exit 0;

sub outer1 {
    my $hello = 'hello';

    # local *inner = sub {
    my $inner = sub {
        say $hello;
    };
    outer2();
}

sub outer2 {
    # inner();
    $inner->();
}

__END__
Global symbol "$inner" requires explicit package name at /tmp/subtst.pl line 20.
Execution of /tmp/subtst.pl aborted due to compilation errors.