sub {
  print "\$_[0]: ",\$_[0], $/;
  local *_= \$_[0];
  print "\$_:    ",*main::_{SCALAR}, $/;
  s///;
}->("foo");

__output__

$_[0]: SCALAR(0x8107ec8)
$_:    SCALAR(0x8107ec8)
Modification of a read-only value attempted at - line 5.