[Boulder.pm] mod_perl package lexicals becoming corrupt

[Rob Nagler]

Found the bug.  Here's what demonstrates it:

    package T1;
    use strict;
    sub s1 {}

    package T2;
    use base 'T1';
    use strict;

    package main;
    T2->s1;
    print("ok\n");
    \&T2::s1;
    print("not reached\n");
    T2->s1;

The \&T2:s1 autovivifies something in the package hash, which is
"nasty", and actually ends up corrupting the package hash so that
lexicals disappear.  We had a function called super_for_method, which
did this:

    foreach my $a (@{$proto->inheritance_ancestors}) {
 	my($sub) = \&{$a . '::' . $method};
 	next unless defined(&$sub);
 	return ($sub, $a);
    }

The fact that \&{} seems to autovivify an invalid package hash entry
is the problem.  You can implement the above this way:

    foreach my $a (@{$proto->inheritance_ancestors}) {
	my($sub) = $a . '::' . $method;
	do {
	    no strict 'refs';
	    next unless defined(&$sub);
	};
	return (\&$sub, $a);
    }

The above code does not corrupt the the package hash.  Both pieces of
code autovivify the glob for $sub, but in the former case, the
autovivification has a dangerous side effect of corrupting the entire
symbol table (in a subtle way, of course, which is why I got confused
by the number of lexicals).

Rob