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Document why it's a bad plan to move the backreferences array from
[perl5.git] / hv.c
diff --git a/hv.c b/hv.c
index e560ba7..27c4bec 100644 (file)
--- a/hv.c
+++ b/hv.c
@@ -1664,11 +1664,16 @@ S_hfreeentries(pTHX_ HV *hv)
     if (iter) {
        if (iter->xhv_backreferences) {
            /* So donate them to regular backref magic to keep them safe. The
-              sv_magic will increase the reference count of the AV, so we need
-              to drop it first.  */
+              sv_magic will increase the reference count of the AV, so we
+              need to drop it first. */
            SvREFCNT_dec(iter->xhv_backreferences);
-           sv_magic((SV*)hv, (SV*)iter->xhv_backreferences,
-                    PERL_MAGIC_backref, NULL, 0);
+           if (AvFILLp(iter->xhv_backreferences) == -1) {
+               /* Turns out that the array is empty. Just free it.  */
+               SvREFCNT_dec(iter->xhv_backreferences);
+           } else {
+               sv_magic((SV*)hv, (SV*)iter->xhv_backreferences,
+                        PERL_MAGIC_backref, NULL, 0);
+           }
            iter->xhv_backreferences = 0;
        }
     }