Implement type checks for switch expression

runtime/vm/scopes.h

Index: runtime/vm/scopes.h
===================================================================
--- runtime/vm/scopes.h	(revision 28998)
+++ runtime/vm/scopes.h	(working copy)
@@ -27,7 +27,7 @@
     : token_pos_(token_pos),
       name_(name),
       owner_(NULL),
-      type_(type),
+      type_(&type),

[regis, 2013/10/22 23:17:20]

Why change this now? We usually do not store a pointer in scope, ast, graph,
etc...

[hausner, 2013/10/22 23:22:18]

Because I have to change the type of a variable after it's created. I don't know
the type of the temporary variable holding the evaluated switch expression until
the case clauses have been parsed. Do you have a better idea how to add the type
check to the internal variable retroactively?

       const_value_(NULL),
       is_final_(false),
       is_captured_(false),
@@ -45,7 +45,11 @@
     owner_ = owner;
   }
 
-  const AbstractType& type() const { return type_; }
+  const AbstractType& type() const { return *type_; }
+  void set_type(const AbstractType& value) {
+    ASSERT(value.IsZoneHandle());
+    type_ = &value;
+  }
 
   bool is_final() const { return is_final_; }
   void set_is_final() { is_final_ = true; }
@@ -101,7 +105,7 @@
   const String& name_;
   LocalScope* owner_;  // Local scope declaring this variable.
 
-  const AbstractType& type_;  // Declaration type of local variable.
+  const AbstractType* type_;  // Declaration type of local variable.
 
   const Instance* const_value_;   // NULL or compile-time const value.