Making CompileType a Value object.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
===================================================================
--- runtime/vm/intermediate_language.h	(revision 18930)
+++ runtime/vm/intermediate_language.h	(working copy)
@@ -113,11 +113,24 @@
 // Values of CompileType form a lattice with a None type as a bottom and a
 // nullable Dynamic type as a top element. Method Union provides a join
 // operation for the lattice.
-class CompileType {
+class CompileType : public ValueObject {
  public:
   static const bool kNullable = true;
   static const bool kNonNullable = false;
 
+  CompileType(const CompileType& other)
+      : ValueObject(),
+        is_nullable_(other.is_nullable_),
+        cid_(other.cid_),
+        type_(other.type_) { }
+
+  CompileType& operator=(const CompileType& other) {
+    is_nullable_ = other.is_nullable_;
+    cid_ = other.cid_;
+    type_ =  other.type_;
+    return *this;
+  }
+

[Florian Schneider, 2013/02/25 11:18:20]

This introduces additional unnecessary dependencies, i.e. whenever adding a
field to CompileType, both have to be updated. Why duplicate the default
behavior of both the copy constructor and the assignment object?

[srdjan, 2013/02/25 17:30:36]

What do you suggest as alternative? Implicit copy constructors should not be
used (see Google style guide).

   // Return type such that concrete value's type in runtime is guaranteed to
   // be subtype of it.
   const AbstractType* ToAbstractType();