use strict;
use warnings;

printf "x=%s\n",
   do {
      my $x = 2;
      sub { $x }
   }->() // 'undef';

printf "x=%s\n",
   do {
      my $x = 2;
      sub { eval '$x' }
   }->() // 'undef';

##</code><code>##

x=2
Variable "$x" is not available at (eval 1) line 2.
x=undef