keep outer block context right in wanted pass

When descending subtrees in the interleaved 'wanted' pass, we can visit
blocks that are done compiling, which means the @!BLOCKS stack in World is
no longer correct.  When entering such a node, we set $*WANTEDOUTERBLOCK
to the correct outer block context, and generate new blocks within
that context.  (This dynvar is a bit of a bandaid that will hopefully no
longer be needed after we switch to following outer chains for everything,
rather than always assuming (as the @!BLOCKS routines assume) that World
routines are only for the single bottom-up pass that happens during parsing.)

src/Perl6/Actions.nqp

@@ -76,6 +76,7 @@ sub wanted($ast,$by) {
     }
     elsif nqp::istype($ast,QAST::Block) {
         my int $i := 1;
+        my $*WANTEDOUTERBLOCK := $ast;
         while $i <= $e {
             $ast[$i] := WANTED($ast[$i], $byby);
             ++$i;
@@ -115,26 +116,24 @@ sub wanted($ast,$by) {
             # we always have a body
             my $cond := WANTED($ast[0],$byby);
             my $body := WANTED($ast[1],$byby);
+            my $block := Perl6::Actions::make_thunk_ref($body, $body.node);
             my $past := QAST::Op.new(:op<callmethod>, :name<from-loop>, :node($body.node),
                 QAST::WVal.new( :value($*W.find_symbol(['Seq']))),
-                block_closure(Perl6::Actions::make_thunk_ref($body, $body.node)) );
+                block_closure($block) );
 
             # conditional (if not always true (or if repeat))
-            $past.push( block_closure(
-                Perl6::Actions::make_thunk_ref(
-                    $while
-                        ?? $cond
-                        !! QAST::Op.new( :op<callmethod>, :name<not>, $cond ),
-                    nqp::can($cond,'node')
-                        ?? $cond.node
-                        !! $body.node
-                )
-            ))
-                if $repeat || !$cond.has_compile_time_value || !$cond.compile_time_value == $while;
+            if $repeat || !$cond.has_compile_time_value || !$cond.compile_time_value == $while {
+                $cond := QAST::Op.new( :op<callmethod>, :name<not>, $cond ) unless $while;
+                $block := Perl6::Actions::make_thunk_ref($cond, nqp::can($cond,'node') ?? $cond.node !! $body.node);
+                $past.push( block_closure($block) );
+            }
 
             # 3rd part of loop, if any
-            $past.push( UNWANTED(block_closure(Perl6::Actions::make_thunk_ref($ast[2], $ast[2].node)),$byby) )
-                if +@($ast) > 2;
+            if +@($ast) > 2 {
+                $block := Perl6::Actions::make_thunk_ref($ast[2], $ast[2].node);
+                $block.annotate('outer',$*WANTEDOUTERBLOCK) if $*WANTEDOUTERBLOCK;
+                $past.push( UNWANTED(block_closure($block),$byby) )
+            }
 
             if $repeat {
                 my $wval := QAST::WVal.new( :value($*W.find_symbol(['True'])) );
@@ -228,6 +227,8 @@ sub unwanted($ast, $by) {
     }
     elsif nqp::istype($ast,QAST::Block) {
         my int $i := 1;
+        my $*WANTEDOUTERBLOCK := $ast;
+        note('++ ' ~ ($*W.is_lexically_visible('&prefix:<++>',$ast) ?? "yes" !! "no"));
         while $i <= $e {
             $ast[$i] := UNWANTED($ast[$i], $byby);
             ++$i;

src/Perl6/World.nqp

@@ -426,7 +426,10 @@ class Perl6::World is HLL::World {
     method push_lexpad($/) {
         # Create pad, link to outer, annotate with creating statement, and add to stack.
         my $pad := QAST::Block.new( QAST::Stmts.new( :node($/) ) );
-        if +@!BLOCKS {
+        if $*WANTEDOUTERBLOCK {  # (outside of 1st push/pop pass)
+            $pad.annotate('outer', $*WANTEDOUTERBLOCK);
+        }
+        elsif +@!BLOCKS {
             $pad.annotate('outer', @!BLOCKS[+@!BLOCKS - 1]);
         }
         $pad.annotate('statement_id', $*STATEMENT_ID);
@@ -1899,7 +1902,12 @@ class Perl6::World is HLL::World {
 
     # Creates a simple code object with an empty signature
     method create_simple_code_object($block, $type) {
-        self.cur_lexpad()[0].push($block);
+        if $*WANTEDOUTERBLOCK {
+            $*WANTEDOUTERBLOCK[0].push($block);
+        }
+        else {
+            self.cur_lexpad()[0].push($block);
+        }
         my $sig := self.create_signature(nqp::hash('parameter_objects', []));
         return self.create_code_object($block, $type, $sig);
     }
@@ -3453,12 +3461,24 @@ class Perl6::World is HLL::World {
         # scopes.
         if +@name == 1 {
             my $final_name := @name[0];
-            my int $i := $start_scope;
-            while $i > 0 {
-                $i := $i - 1;
-                my %sym := @!BLOCKS[$i].symbol($final_name);
-                if +%sym {
-                    return self.force_value(%sym, $final_name, 1);
+            if $*WANTEDOUTERBLOCK {
+                my $scope := $*WANTEDOUTERBLOCK;
+                while $scope {
+                    my %sym := $scope.symbol($final_name);
+                    if +%sym {
+                        return self.force_value(%sym, $final_name, 1);
+                    }
+                    $scope := $scope.ann('outer');
+                }
+            }
+            else {
+                my int $i := $start_scope;
+                while $i > 0 {
+                    $i := $i - 1;
+                    my %sym := @!BLOCKS[$i].symbol($final_name);
+                    if +%sym {
+                        return self.force_value(%sym, $final_name, 1);
+                    }
                 }
             }
         }