Assigning to DEFSV leaks if PL_defgv's gp_sv isn't set.

As Nicholas already noted in a FIXME, assigning to DEFSV should
use GvSV instead of GvSVn. This change ensures that, at least
under -DPERL_CORE, DEFSV cannot be assigned to and introduces
a DEFSV_set macro to allow setting DEFSV.
This fixes #53038: map leaks memory.

p4raw-id: //depot/perl@34776

1 files changed, 1 insertions, 1 deletions

diff --git a/pp_hot.c b/pp_hot.c
index eeedc5b375..6450e25f35 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -2424,7 +2424,7 @@ PP(pp_grepwhile)
 	if (PL_op->op_private & OPpGREP_LEX)
 	    PAD_SVl(PL_op->op_targ) = src;
 	else
-	    DEFSV = src;
+	    DEFSV_set(src);
 
 	RETURNOP(cLOGOP->op_other);
     }