sub caller_info {
  my $i = shift(@_) + 1;
  my %call_info;
  {
  package DB;
  @args = \$i; # A sentinal, which no-one else has the address of
  @call_info{
    qw(pack file line sub has_args wantarray evaltext is_require)
  } = defined &{"CORE::GLOBAL::caller"} ? &{"CORE::GLOBAL::caller"}($i
+) : caller($i);
  }

  unless (defined $call_info{pack}) {
    return ();
  }

  my $sub_name = Carp::get_subname(\%call_info);
  if ($call_info{has_args}) {
    my @args;
    if (@DB::args == 1 && ref $DB::args[0] eq ref \$i && $DB::args[0] 
+== \$i) {
      @DB::args = (); # Don't let anyone see the address of $i
      @args = "** Incomplete caller override detected; \@DB::args were
+ not set **";
    } else {
      @args = map {Carp::format_arg($_)} @DB::args;
    }
    if ($MaxArgNums and @args > $MaxArgNums) { # More than we want to 
+show?
      $#args = $MaxArgNums;
      push @args, '...';
    }
    # Push the args onto the subroutine
    $sub_name .= '(' . join (', ', @args) . ')';
  }
  $call_info{sub_name} = $sub_name;
  return wantarray() ? %call_info : \%call_info;
}
[download]

Again, I can almost see what's going on here, but not quite. It looks like the if ($call_info{has_args}) is only there to keep from checking args when there really weren't any, so perhaps it's not as big a piece of the puzzle as I had suspected. The main question is, what exactly is supposed to be triggering that "incomplete override" message?