From @carbin

Also occurs with methods etc.

sub foo { my $a = "baz"; undefine $a; }; say foo;
Null PMC access in type()
in Main (<unknown>​:1)

--
Carlin

From @carbin

On a side note, it looks like there are inconsistencies in the Null
PMC access error messages ;-)

23​:22 < carlin> rakudo​: sub foo {}; undefine undefine foo;
23​:22 <+p6eval> rakudo 0d77e4​: OUTPUT«Null PMC in copy␤»

--
Carlin

From @carbin

More undefined silliness :-)

04​:31 < carlin> rakudo​: sub foo($bar) { say $bar }; my $x = 'x';
foo(undefine $x);
04​:31 <+p6eval> rakudo 0d77e4​: OUTPUT«Null PMC access in isa()␤in sub foo
  (/tmp/MFiaifDhR7​:2)␤called from Main (/tmp/MFiaifDhR7​:2)␤»

--
Carlin

From jswitzer@gmail.com

This patch should move undefine to the setting, providing both the multi
method and the multi sub. Note that the is export is not working in
aliased classes. If that is fixed, remove the multi sub and add is
export to the multi method.

-Jason "s1n" Switzer

From jswitzer@gmail.com

diff --git a/src/builtins/named-unary.pir b/src/builtins/named-unary.pir
index 6d67a70..ca82b6d 100644
--- a/src/builtins/named-unary.pir
+++ b/src/builtins/named-unary.pir
@@ -45,19 +45,6 @@ Returns a true value if $x is defined, and a false value otherwise.
 .end
 
 
-=item undefine $x
-
-Sets $x to an undefined value
-
-=cut
-
-.sub 'undefine'
-    .param pmc x
-    $P0 = root_new ['parrot';'Perl6Scalar']
-    copy x, $P0
-.end
-
-
 =back
 
 =cut
diff --git a/src/setting/Object.pm b/src/setting/Object.pm
index b406657..7e3b54a 100644
--- a/src/setting/Object.pm
+++ b/src/setting/Object.pm
@@ -73,6 +73,14 @@ class Object is also {
 
         return @methods;
     }
+
+    multi method undefine() {
+        self = undef;
+    }
+}
+
+multi sub undefine($x) {
+    $x.undefine;
 }
 
 # vim: ft=perl6

jswitzer@gmail.com - Status changed from 'new' to 'open'

From @moritz

I'm not sure if the patch attached to this ticket ever got applied, but
undefine() now lives in the setting, there's no Null PMC access anymore,
and there's a test in S32-scalar/undef.t -- so all in all nothing
prevents me from closing this ticket for good :-).

@moritz - Status changed from 'open' to 'resolved'