It is quite limited by Perl's quirky syntax, unfortunately ("only Perl can parse Perl"). Last time I checked, it would miss e.g. all warnings for anonymous subs:

  # triggers "Subroutine "foo" does not end with "return" at line 5, column 1.  See page 197 of PBP.  (Severity: 4)"
  sub foo {
      my $s=shift;
  }

  # triggers no warnings 
  my $x = sub {
      my $s=shift;
  }