From: Jarkko Hietaniemi <jhi@iki.fi>
Date: Wed, 25 Oct 2000 20:43:10 +0000 (+0000)
Subject: Temporary stopgap for the self-tying issue: for now only
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=ae21d580cc4565c4ab54286c723cd431c96dedeb;p=p5sagit%2Fp5-mst-13.2.git

Temporary stopgap for the self-tying issue: for now only
array and hash self-ties are verboten.  The real fix, of
course, would be to comprehensively test (and implement?)
and debug (and document) self-ties.

p4raw-id: //depot/perl@7443
---

diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index 139bab9..3994531 100644
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -2903,9 +2903,10 @@ filehandle that was either never opened or has since been closed.
 
 (F) This machine doesn't implement the select() system call.
 
-=item Self-ties are not supported
+=item Self-ties of arrays and hashes are not supported
 
-(F) Self-ties are not supported in the current implementation.
+(F) Self-ties are of arrays and hashes are not supported in
+the current implementation.
 
 =item Semicolon seems to be missing
 
diff --git a/pp_sys.c b/pp_sys.c
index c7cbd46..28ffcda 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -802,9 +802,12 @@ PP(pp_tie)
     POPSTACK;
     if (sv_isobject(sv)) {
 	sv_unmagic(varsv, how);
-	/* Croak if a self-tie is attempted */
-	if (varsv == SvRV(sv))
-	    Perl_croak(aTHX_ "Self-ties are not supported");
+	/* Croak if a self-tie on an aggregate is attempted. */
+	if (varsv == SvRV(sv) &&
+	    (SvTYPE(sv) == SVt_PVAV ||
+	     SvTYPE(sv) == SVt_PVHV))
+	    Perl_croak(aTHX_
+		       "Self-ties of arrays and hashes are not supported");
 	sv_magic(varsv, sv, how, Nullch, 0);
     }
     LEAVE;
diff --git a/t/op/tie.t b/t/op/tie.t
index afcc4a1..4413ed2 100755
--- a/t/op/tie.t
+++ b/t/op/tie.t
@@ -162,19 +162,28 @@ $C = $B = tied %H ;
 untie %H;
 EXPECT
 ########
-
-# verify no leak when underlying object is selfsame tied variable
-my ($a, $b);
+# Forbidden aggregate self-ties
+my ($a, $b) = (0, 0);
 sub Self::TIEHASH { bless $_[1], $_[0] }
-sub Self::DESTROY { $b = $_[0] + 0; }
+sub Self::DESTROY { $b = $_[0] + 1; }
+{
+    my %c = 42;
+    tie %c, 'Self', \%c;
+}
+EXPECT
+Self-ties of arrays and hashes are not supported 
+########
+# Allowed scalar self-ties
+my ($a, $b) = (0, 0);
+sub Self::TIESCALAR { bless $_[1], $_[0] }
+sub Self::DESTROY   { $b = $_[0] + 1; }
 {
-    my %b5;
-    $a = \%b5 + 0;
-    tie %b5, 'Self', \%b5;
+    my $c = 42;
+    $a = $c + 0;
+    tie $c, 'Self', \$c;
 }
-die unless $a == $b;
+die unless $a == 0 && $b == 43;
 EXPECT
-Self-ties are not supported 
 ########
 # Interaction of tie and vec