Stop padlists from being AVs

In order to fix a bug, I need to add new fields to padlists.  But I
cannot easily do that as long as they are AVs.

So I have created a new padlist struct.

This not only allows me to extend the padlist struct with new members
as necessary, but also saves memory, as we now have a three-pointer
struct where before we had a whole SV head (3-4 pointers) + XPVAV (5
pointers).

This will unfortunately break half of CPAN, but the pad API docs
clearly say this:

    NOTE: this function is experimental and may change or be
    removed without notice.

This would have broken B::Debug, but a patch sent upstream has already
been integrated into blead with commit 9d2d23d981.

1 files changed, 1 insertions, 1 deletions

diff --git a/dump.c b/dump.c
index bad42b5499..0b2eee01e1 100644
--- a/dump.c
+++ b/dump.c
@@ -2178,7 +2178,7 @@ Perl_debop(pTHX_ const OP *o)
 	SV *sv;
         if (cv) {
 	    PADLIST * const padlist = CvPADLIST(cv);
-            AV * const comppad = MUTABLE_AV(*av_fetch(padlist, 0, FALSE));
+            PAD * const comppad = *PADLIST_ARRAY(padlist);
             sv = *av_fetch(comppad, o->op_targ, FALSE);
         } else
             sv = NULL;