#!perl -w
$o = q{qq{ $& | $'}};
$p = q{2};
$_=1234;
/$p/;
print eval $o;
/$p/;
print eval $o;
__END__
Use of uninitialized value $& in concatenation (.) or string at (eval 1) line 1.
Use of uninitialized value $' in concatenation (.) or string at (eval 1) line 1.
  |  2 | 34