From 8505eec04db975056f12e93f306696ee3bf089ad Mon Sep 17 00:00:00 2001
From: Father Chrysostomos <sprout@cpan.org>
Date: Mon, 9 Jan 2012 22:18:56 -0800
Subject: Fix crash in hv_undef
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Commit 60edcf09a was supposed to make things less buggy, but putting
the ENTER/LEAVE in h_freeentries was a mistake, as both hv_undef and
hv_clear still access the hv after calling h_freeentries.  Why it
didn’t crash for me is anyone’s guess.
---
 hv.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/hv.c b/hv.c
index baeeae711f..f166968195 100644
--- a/hv.c
+++ b/hv.c
@@ -1566,6 +1566,8 @@ Perl_hv_clear(pTHX_ HV *hv)
 
     xhv = (XPVHV*)SvANY(hv);
 
+    ENTER;
+    SAVEFREESV(SvREFCNT_inc_simple_NN(hv));
     if (SvREADONLY(hv) && HvARRAY(hv) != NULL) {
 	/* restricted hash: convert all keys to placeholders */
 	STRLEN i;
@@ -1603,6 +1605,7 @@ Perl_hv_clear(pTHX_ HV *hv)
             mro_isa_changed_in(hv);
 	HvEITER_set(hv, NULL);
     }
+    LEAVE;
 }
 
 /*
@@ -1684,20 +1687,12 @@ S_hfreeentries(pTHX_ HV *hv)
     STRLEN index = 0;
     XPVHV * const xhv = (XPVHV*)SvANY(hv);
     SV *sv;
-    const bool save = !!SvREFCNT(hv);
 
     PERL_ARGS_ASSERT_HFREEENTRIES;
 
-    if (save) {
-	ENTER;
-	SAVEFREESV(SvREFCNT_inc_simple_NN(hv));
-    }
-
     while ((sv = Perl_hfree_next_entry(aTHX_ hv, &index))||xhv->xhv_keys) {
 	SvREFCNT_dec(sv);
     }
-
-    if (save) LEAVE;
 }
 
 
@@ -1790,6 +1785,7 @@ Perl_hv_undef_flags(pTHX_ HV *hv, U32 flags)
     dVAR;
     register XPVHV* xhv;
     const char *name;
+    const bool save = !!SvREFCNT(hv);
 
     if (!hv)
 	return;
@@ -1814,6 +1810,10 @@ Perl_hv_undef_flags(pTHX_ HV *hv, U32 flags)
                            );
 	hv_name_set(hv, NULL, 0, 0);
     }
+    if (save) {
+	ENTER;
+	SAVEFREESV(SvREFCNT_inc_simple_NN(hv));
+    }
     hfreeentries(hv);
     if (SvOOK(hv)) {
       struct xpvhv_aux * const aux = HvAUX(hv);
@@ -1867,6 +1867,7 @@ Perl_hv_undef_flags(pTHX_ HV *hv, U32 flags)
 
     if (SvRMAGICAL(hv))
 	mg_clear(MUTABLE_SV(hv));
+    if (save) LEAVE;
 }
 
 /*
-- 
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