use B find out FILE and LINE of reference

B-ref-line-and-file.pl

# ----------- use B ---------------- #
# B is perl compiler backend


require B;

my $ref = sub { 
  print "Hello, world !\n";
};

my $gv = B::svref_2object($ref)->GV;

print 'variable $ref at :', $gv->LINE, ' line of file ', $gv->FILE, "\n";

__END__
# -------------- result -------------- #

=begin result

variable $ref at :7 line of file tp.pl

=end result
=cut