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, 3 insertions, 3 deletions

diff --git a/perl.h b/perl.h
index 5be85c46e5..1154c40ca8 100644
--- a/perl.h
+++ b/perl.h
@@ -2442,9 +2442,9 @@ typedef struct ptr_tbl_ent PTR_TBL_ENT_t;
 typedef struct ptr_tbl PTR_TBL_t;
 typedef struct clone_params CLONE_PARAMS;
 
-/* a padlist is currently just an AV; but that might change,
- * so hide the type. Ditto a pad.  */
-typedef AV PADLIST;
+/* a pad is currently just an AV; but that might change,
+ * so hide the type.  */
+typedef struct padlist PADLIST;
 typedef AV PAD;
 
 #include "handy.h"