in reply to mapping warning from an eval code to actual line in text

eval q{#line 1 "blah blah"
  die "Hello" if 1;
} or die @$;

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See "Plain Old Comments (Not!)" in perlsyn

package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name

In Section Seekers of Perl Wisdom