Remove the "Can't provide tied hash usage" error from perldiag.

Mention the new tied hash SCALAR method in perldelta.

p4raw-id: //depot/perl@21857

1 files changed, 16 insertions, 13 deletions

diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index f8b5deaa86..9ebb2edb60 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -216,6 +216,22 @@ contains a package variable named C<$NEGATIVE_INDICES> which is set to
 a true value, negative values will be passed to C<FETCH>, C<STORE>,
 C<EXISTS>, and C<DELETE> unchanged.
 
+=head2 Tied hashes in scalar context
+
+As of perl 5.8.2, tied hashes did not return anything useful in scalar
+context, for example when used as boolean tests:
+
+	if (%tied_hash) { ... }
+
+The old nonsensical behaviour was always to return false,
+regardless of whether the hash is empty or has elements.
+
+There is now an interface for the implementors of tied hashes to implement
+the behaviour of a hash in scalar context, via the SCALAR method (see
+L<perltie>).  Without a SCALAR method, perl will try to guess whether
+the hash is empty, by testing if it's inside an iteration (in this case
+it can't be empty) or by calling FIRSTKEY.
+
 =head2 local ${$x}
 
 The syntaxes
@@ -861,19 +877,6 @@ common Perl platforms (Unix and Unix-like, Microsoft platforms, and
 VMS) have large enough testing and expert population that they are
 doing well.
 
-=head2 Tied hashes in scalar context
-
-Tied hashes do not currently return anything useful in scalar context,
-for example when used as boolean tests:
-
-	if (%tied_hash) { ... }
-
-The current nonsensical behaviour is always to return false,
-regardless of whether the hash is empty or has elements.
-
-The root cause is that there is no interface for the implementors of
-tied hashes to implement the behaviour of a hash in scalar context.
-
 =head2 Net::Ping 450_service and 510_ping_udp failures
 
 The subtests 9 and 18 of lib/Net/Ping/t/450_service.t, and the