add CvSTASH_set() macro and make CvSTASH() rvalue only

Now that CvSTASH requires backreference bookkeeping, stop people from
directly assigning to it (by using CvSTASH() as an lvalue), and instead
force them to use CvSTASH_set().

1 files changed, 1 insertions, 3 deletions

diff --git a/pad.c b/pad.c
index e945113a4a..d395e71dfe 100644
--- a/pad.c
+++ b/pad.c
@@ -1573,9 +1573,7 @@ Perl_cv_clone(pTHX_ CV *proto)
     CvFILE(cv)		= CvFILE(proto);
 #endif
     CvGV_set(cv,CvGV(proto));
-    CvSTASH(cv)		= CvSTASH(proto);
-    if (CvSTASH(cv))
-	Perl_sv_add_backref(aTHX_ MUTABLE_SV(CvSTASH(cv)), MUTABLE_SV(cv));
+    CvSTASH_set(cv, CvSTASH(proto));
     OP_REFCNT_LOCK;
     CvROOT(cv)		= OpREFCNT_inc(CvROOT(proto));
     OP_REFCNT_UNLOCK;