Implement type checks for switch expression

runtime/vm/scopes.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_SCOPES_H_
 #define VM_SCOPES_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/growable_array.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
 class BitVector;
 class JoinEntryInstr;
 class LocalScope;
 class LocalVariable;
 class SourceLabel;
 
 
 class LocalVariable : public ZoneAllocated {
  public:
   LocalVariable(intptr_t token_pos,
                 const String& name,
                 const AbstractType& type)
     : 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),
       is_invisible_(false),
       index_(LocalVariable::kUninitializedIndex) {
     ASSERT(type.IsZoneHandle());
     ASSERT(type.IsFinalized());
   }
 
   intptr_t token_pos() const { return token_pos_; }
   const String& name() const { return name_; }
   LocalScope* owner() const { return owner_; }
   void set_owner(LocalScope* owner) {
     ASSERT(owner_ == NULL);
     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; }
 
   bool is_captured() const { return is_captured_; }
   void set_is_captured() { is_captured_ = true; }
 
   bool HasIndex() const {
     return index_ != kUninitializedIndex;
   }
@@ skipping 35 matching lines @@
   // all parameters.
   int BitIndexIn(intptr_t var_count) const;
 
  private:
   static const int kUninitializedIndex = INT_MIN;
 
   const intptr_t token_pos_;
   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.
 
   bool is_final_;  // If true, this variable is readonly.
   bool is_captured_;  // If true, this variable lives in the context, otherwise
                       // in the stack frame.
   bool is_invisible_;
   int index_;  // Allocation index in words relative to frame pointer (if not
                // captured), or relative to the context pointer (if captured).
 
@@ skipping 251 matching lines @@
   intptr_t end_token_pos_;    // Token index of end of scope.
   GrowableArray<LocalVariable*> variables_;
   GrowableArray<SourceLabel*> labels_;
 
   DISALLOW_COPY_AND_ASSIGN(LocalScope);
 };
 
 }  // namespace dart
 
 #endif  // VM_SCOPES_H_