VM: Fix bug in deferred loading.

runtime/vm/ast.h

Index: runtime/vm/ast.h
diff --git a/runtime/vm/ast.h b/runtime/vm/ast.h
index ef265639dc34d025ec93bbf489975616f0e8a1bd..0560dbcc6e8fb3ea3fcb1825a4d07c68f04d556b 100644
--- a/runtime/vm/ast.h
+++ b/runtime/vm/ast.h
@@ -564,14 +564,15 @@ class ClosureNode : public AstNode {
 class PrimaryNode : public AstNode {
  public:
   PrimaryNode(TokenPosition token_pos, const Object& primary)
-      : AstNode(token_pos), primary_(primary), is_deferred_reference_(false) {
+      : AstNode(token_pos), primary_(primary), prefix_(NULL) {
     ASSERT(primary_.IsNotTemporaryScopedHandle());
   }
 
   const Object& primary() const { return primary_; }
 
-  void set_is_deferred(bool value) { is_deferred_reference_ = value; }
-  bool is_deferred_reference() const { return is_deferred_reference_; }
+  void set_prefix(const LibraryPrefix* prefix) { prefix_ = prefix; }

[rmacnak, 2017/01/05 22:50:11]

prefix -> deferred_prefix

ASSERT(prefix.is_deferred_load());

[Florian Schneider, 2017/01/06 02:12:12]

Done.

+  const LibraryPrefix* prefix() const { return prefix_; }
+  bool is_deferred_reference() const { return prefix_ != NULL; }
 
   bool IsSuper() const {
     return primary().IsString() && (primary().raw() == Symbols::Super().raw());
@@ -583,7 +584,7 @@ class PrimaryNode : public AstNode {
 
  private:
   const Object& primary_;
-  bool is_deferred_reference_;
+  const LibraryPrefix* prefix_;

[hausner, 2017/01/05 21:50:44]

We don't typically store pointers to handles in the ast.

[Florian Schneider, 2017/01/05 22:07:16]

I'd have to allocate an extra handle per PrimaryNode, right?
Also, we do store pointers to handles in a few places in
intermediate_language.h, so I don't see why not in the AST.

Would it be ok if I add an assertion that the pointer points to a ZoneHandle?
(i.e. not a scoped handle)

[hausner, 2017/01/05 22:39:40]

Fine with me. Yes, otherwise you'd have to allocate a handle. Or else you
introduce a null handle in the VM isolate, but that's overkill I think.

 
   DISALLOW_IMPLICIT_CONSTRUCTORS(PrimaryNode);
 };