use strict;
use warnings;

use Data::Dump qw(pp dd);
use PadWalker qw/var_name/;

sub _ { return var_name(1, \$_[0] ) => $_[0] }

sub t_ { _ my $xxx=666 }

dd [ t_ ];                     # works: ["\$xxx", 666]

dd [ _ my $xxx=666 ];          # works: ["\$xxx", 666]

dd [ eval '_ my $xxx=666' ];   # fails: [undef, 666]