get rid of NestParentByRefBit

Eigen/src/Core/util/Constants.h

@@ -97,7 +97,6 @@ const unsigned int EvalBeforeAssigningBit = 0x4;
   */
 const unsigned int PacketAccessBit = 0x8;
 
-const unsigned int NestParentByRefBit = 0x80;
 const unsigned int NestByRefBit = 0x100;
 
 #ifdef EIGEN_VECTORIZE

Eigen/src/Core/util/XprHelper.h

@@ -201,28 +201,6 @@ template<typename T> struct ei_plain_matrix_type_row_major
 // we should be able to get rid of this one too
 template<typename T> struct ei_must_nest_by_value { enum { ret = false }; };
 
-template<class T>
-struct ei_is_reference
-{
-#ifndef NDEBUG
-  static void check() { std::cout << typeid(T).name() << std::endl; }
-#else
-  static void check() {}
-#endif
-  enum { ret = false };
-};
-
-template<class T>
-struct ei_is_reference<T&>
-{
-#ifndef NDEBUG
-  static void check() { std::cout << typeid(T).name() << "&" << std::endl; }
-#else
-  static void check() {}
-#endif
-  enum { ret = true };
-};
-
 /**
 * The reference selector for template expressions. The idea is that we don't
 * need to use references for expressions since they are light weight proxy
@@ -238,8 +216,6 @@ struct ei_ref_selector
   >::ret type;
 };
 
-#define EIGEN_PROPAGATE_NESTING_BIT(ReferenceFlags) ((ReferenceFlags) & NestParentByRefBit)<<1
-
 /** \internal Determines how a given expression should be nested into another one.
   * For example, when you do a * (b+c), Eigen will determine how the expression b+c should be
   * nested into the bigger product expression. The choice is between nesting the expression b+c as-is, or