Update method caches for non-void stash elem deletions

Commit 71be2cb (inseparable changes from patch from perl5.003_13 to
perl5.003_14) added code to hv_free_ent to reset method caches if
necessary.

Later, a bug fix in the deletion code (f50383f5) made it necessary for
the value in the HE to be set to &PL_sv_placeholder, so it wouldn’t
free the sv just yet.  So the method cache code (which by then had
changed from using PL_sub_generation to using mro_method_changed_in)
got repeated in S_hv_delete_common.

The only problem with all this is that hv_free_ent was the wrong place
to put it to begin with.  If delete is called in non-void context,
the sv in it is not freed just yet, but returned; so hv_free_ent was
already being called with a HE pointing to &PL_sv_placeholder.

Commit f50383f5 only added the mro code for the void case, to avoid
changing existing behaviour when rearranging the code.

It turns out it needs to be done in S_hv_delete_common uncon-
ditionally.

Changing a test in t/op/method.t to use ()=delete instead of delete
makes it fail, because method caches end up going stale.  See the test
in the diff.

1 files changed, 10 insertions, 8 deletions

diff --git a/hv.c b/hv.c
index 9a088a923a..e1f80400b5 100644
--- a/hv.c
+++ b/hv.c
@@ -1052,19 +1052,21 @@ S_hv_delete_common(pTHX_ HV *hv, SV *keysv, const char *key, STRLEN klen,
 	if (d_flags & G_DISCARD) {
 	    sv = HeVAL(entry);
 	    HeVAL(entry) = &PL_sv_placeholder;
-	    if (sv) {
-		/* deletion of method from stash */
-		if (isGV(sv) && isGV_with_GP(sv) && GvCVu(sv)
-		 && HvENAME_get(hv))
-		    mro_method_changed_in(hv);
-		SvREFCNT_dec(sv);
-		sv = NULL;
-	    }
 	}
 	else {
 	    sv = sv_2mortal(HeVAL(entry));
 	    HeVAL(entry) = &PL_sv_placeholder;
 	}
+	if (sv) {
+	    /* deletion of method from stash */
+	    if (isGV(sv) && isGV_with_GP(sv) && GvCVu(sv)
+	     && HvENAME_get(hv))
+		mro_method_changed_in(hv);
+	    if (d_flags & G_DISCARD) {
+		SvREFCNT_dec(sv);
+		sv = NULL;
+	    }
+	}
 
 	/*
 	 * If a restricted hash, rather than really deleting the entry, put