Implement proper autovivifying array access

SAFE.setting

@@ -348,9 +348,10 @@ sub infix:<~~>($t,$m) { ($m.defined) ?? ($m.ACCEPTS($t)) !! ($t.^does($m)) }
 # TODO: Implement 'augment'
 
 PRE-INIT {
-    Mu.HOW.add-method("defined", anon method defined() {
+    # rawcall to avoid putting a rw binding on self... TODO
+    Mu.HOW.add-method("defined", anon method defined is rawcall {
             Q:CgOp { (box Bool (!= (null Dictionary<string,object>)
-                (getfield slots (cast DynObject (@ (l self)))))) }
+                (getfield slots (cast DynObject (@ (pos 0)))))) }
         });
     Mu.HOW.add-method("Bool", anon method Bool() { self.defined });
     Mu.HOW.add-method("Str", anon method Str() {

test2.pl

@@ -58,4 +58,21 @@ sub postcircumfix:<[ ]> is rawcall {
 my @arr = <a b c>;
 is @arr.join("|"), 'a|b|c', "word splitter works";
 
+my @narr;
+@narr[0];
+ok +@narr == 0, "rvalue reference to out of range value does not add";
+@narr[2] = 5;
+ok +@narr == 3, "assigning to element 2 makes length 3";
+ok !(@narr[0].defined), "first element undefined";
+ok !(@narr[1].defined), "second element undefined";
+ok @narr[2] == 5, "third element properly assigned";
+
+my @darr;
+@darr[1][1];
+ok +@darr == 0, "rvalue nested reference, no effect";
+@darr[2][2] = 'pie';
+ok +@darr == 3, "outer level vivifies elements";
+ok @darr[2] ~~ Array, "inner Array created";
+is @darr[2][2], 'pie', "inner value retained";
+
 done-testing;