Calling Perl_hv_clear_placeholders while the hash iterator was active

would turn lazy delete on, causing the hash to become corrupted at the
next iterator change.

p4raw-id: //depot/perl@26551

2 files changed, 21 insertions, 2 deletions

diff --git a/hv.c b/hv.c
index 7452b1ecb0..69c951cfab 100644
--- a/hv.c
+++ b/hv.c
@@ -1617,7 +1617,7 @@ Perl_hv_clear_placeholders(pTHX_ HV *hv)
 		*oentry = HeNEXT(entry);
 		if (first && !*oentry)
 		    HvFILL(hv)--; /* This linked list is now empty.  */
-		if (HvEITER_get(hv))
+		if (entry == HvEITER_get(hv))
 		    HvLAZYDEL_on(hv);
 		else
 		    hv_free_ent(hv, entry);
diff --git a/lib/Hash/Util.t b/lib/Hash/Util.t
index 8ed557f1a3..adce3d171d 100644
--- a/lib/Hash/Util.t
+++ b/lib/Hash/Util.t
@@ -6,7 +6,7 @@ BEGIN {
         chdir 't';
     }
 }
-use Test::More tests => 173;
+use Test::More tests => 179;
 use strict;
 
 my @Exported_Funcs;
@@ -323,3 +323,22 @@ ok($hash_seed >= 0, "hash_seed $hash_seed");
 	is ($counter, 0, "0 objects after clear $state");
     }
 }
+
+{
+    my %hash = map {$_,$_} qw(fwiffffff foosht teeoo);
+    lock_keys(%hash);
+    delete $hash{fwiffffff};
+    is (scalar keys %hash, 2);
+    unlock_keys(%hash);
+    is (scalar keys %hash, 2);
+
+    my ($first, $value) = each %hash;
+    is ($hash{$first}, $value, "Key has the expected value before the lock");
+    lock_keys(%hash);
+    is ($hash{$first}, $value, "Key has the expected value after the lock");
+
+    my ($second, $v2) = each %hash;
+
+    is ($hash{$first}, $value, "Still correct after iterator advances");
+    is ($hash{$second}, $v2, "Other key has the expected value");
+}