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/regexec.c b/regexec.c
index 025d1592f4..6c0923fc8b 100644
--- a/regexec.c
+++ b/regexec.c
@@ -2250,7 +2250,7 @@ S_regtry(pTHX_ regmatch_info *reginfo, char **startpos)
 	    /* Make $_ available to executed code. */
 	    if (reginfo->sv != DEFSV) {
 		SAVE_DEFSV;
-		DEFSV = reginfo->sv;
+		DEFSV_set(reginfo->sv);
 	    }
 	
 	    if (!(SvTYPE(reginfo->sv) >= SVt_PVMG && SvMAGIC(reginfo->sv)