From @masak

Submitting the below message as a bug per John's request.

---------- Forwarded message ----------
From​: John M. Dlugosz <2nb81lz02@​sneakemail.com>
Date​: Mon, Jun 15, 2009 at 4​:43 AM
Subject​: Re​: Why pass by reference?
To​: perl6-language@​perl.org

[...]

No, "is rw" does not like immutables.  It will cause autovivification
to take place, but will not accept something that is not an lvalue
such as 1 or "Hello" literals.  This was just doubled-checked with
S06, S09, and discussion with Larry in #perl6.  If Ra

  <ruoso>    rakudo​: sub foo($a is rw) { $a += 1; say $a }; foo(1);
  <p6eval>   rakudo 77f9d7​: OUTPUT«2␤»

that directly contradicts S06, which states "Otherwise the signature
fails to bind, and this candidate routine cannot be considered for
servicing this particular call."  Doing otherwise affects the
semantics of MMD for allowing overloading based on whether the
parameter is an lvalue or not.

Somebody who works with rakudo could submit a bug, if it's not in there already?

From @kyleha

This is an automatically generated mail to inform you that tests are now available in at least one of these files​: t/spec/S02-magicals/dollar_bang.t, t/spec/S06-multi/by-trait.t

commit a264981ad5f9439aec2e797a9c35b55d354183b1
Author​: kyle <kyle@​c213334d-75ef-0310-aa23-eaa082d1ae64>
Date​: Fri Nov 13 19​:05​:21 2009 +0000

  [t/spec] Tests for RT 66588
 
  git-svn-id​: http://svn.pugscode.org/pugs@&#8203;29071 c213334d-75ef-0310-aa23-eaa082d1ae64

diff --git a/t/spec/S02-magicals/dollar_bang.t b/t/spec/S02-magicals/dollar_bang.t
index 3b33e06..b283493 100644
--- a/t/spec/S02-magicals/dollar_bang.t
+++ b/t/spec/S02-magicals/dollar_bang.t
@@ -40,7 +40,7 @@ ok $!, 'Dividing one by zero sets $!';
 sub incr ( $a is rw ) { $a++ };
 undefine $!;
 try { incr(19) };
-#?rakudo todo 'containers/values'
+#?rakudo todo 'RT 66588: containers/values'
 ok $!, 'Modifying a constant sets $!';
 
 try {
diff --git a/t/spec/S06-multi/by-trait.t b/t/spec/S06-multi/by-trait.t
new file mode 100644
index 0000000..45b33df
--- /dev/null
+++ b/t/spec/S06-multi/by-trait.t
@@ -0,0 +1,23 @@
+use v6;
+use Test;
+plan *;
+
+{
+    my $ro_call = 0;
+    my $rw_call = 0;
+    sub uno_mas( Int $ro       ) { $ro_call++; return 1 + $ro }
+    sub uno_mas( Int $rw is rw ) { $rw_call++; return ++$rw }
+    
+    is uno_mas(42), 43, 'multi works with constant';
+    is $ro_call, 1, 'read-only multi was called';
+
+    my $x = 99;
+    is uno_mas( $x ), 100, 'multi works with variable';
+    #?rakudo 2 todo 'RT 66588: multi dispatch by trait'
+    is $x, 100, 'variable was modified';
+    is $rw_call, 1, 'read-write multi was called';
+}
+
+done_testing;
+
+# vim: ft=perl6

The RT System itself - Status changed from 'new' to 'open'

From @moritz

now fails properly with "Cannot assign to readonly value"

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