[perl #114888] Localise PL_comppad_name in cv_clone

In 9ef8d56 I made closures share their pad name lists, and not just
the names themselves, for speed (no need to SvREFCNT_inc each name and
copy the list).

To make that work, I had to set PL_comppad_name in cv_clone, before
the pad_new call.  But I failed to move the PL_comppad_name localisa-
tion from pad_new to cv_clone.

So cv_clone would merrily clobber the previous value of
PL_comppad_name *before* localising it.

This only manifested itself in source filters.  Most of the time,
pp_anoncode is called at run time when either no code is being com-
piled (PL_comppad_name is only used at compile time) or inside a
BEGIN block which itself localises PL_comppad_name.  But inside a
Filter::Util::Call source filter there was no buffer like that to
protect it.

This meant that pad name creation (my $x) would create the name in the
PL_comppad_name belonging to the last-cloned sub.  A subsequent name
lookup ($x) would look in the correct place, as it uses the moral
equivalent of PadlistNAMES(CvPADLIST(PL_compcv)), not PL_comppad_name.
So it would not find it, resulting in a global variable or a stricture
violation.

1 files changed, 2 insertions, 1 deletions

diff --git a/pad.c b/pad.c
index fd75d4252b..711fd21b97 100644
--- a/pad.c
+++ b/pad.c
@@ -247,8 +247,8 @@ Perl_pad_new(pTHX_ int flags)
 
     if (flags & padnew_SAVE) {
 	SAVECOMPPAD();
-	SAVESPTR(PL_comppad_name);
 	if (! (flags & padnew_CLONE)) {
+	    SAVESPTR(PL_comppad_name);
 	    SAVEI32(PL_padix);
 	    SAVEI32(PL_comppad_name_fill);
 	    SAVEI32(PL_min_intro_pending);
@@ -2004,6 +2004,7 @@ Perl_cv_clone(pTHX_ CV *proto)
     if (SvMAGIC(proto))
 	mg_copy((SV *)proto, (SV *)cv, 0, 0);
 
+    SAVESPTR(PL_comppad_name);
     PL_comppad_name = protopad_name;
     CvPADLIST(cv) = pad_new(padnew_CLONE|padnew_SAVE);
     CvPADLIST(cv)->xpadl_id = protopadlist->xpadl_id;