During the port of 32-bit programs on the 64-bit platform the change of the logic of its work may be found which is related to the use of overload functions. If the function is overlapped for 32-bit and 64-bit values the access to it with the argument of memsize type will be compiled into different calls on different systems. This method may be useful as, for example, in the following code:

static size_t GetBitCount(const unsigned __int32 &) {
  return 32;
}

static size_t GetBitCount(const unsigned __int64 &) {
  return 64;
}

size_t a;
size_t bitCount = GetBitCount(a);

But such a change of logic has a potential danger. Imagine a program in which a class for organizing stack is used for some aims. The peculiarity of this class is that it allows to store value of different types.

class MyStack {
...
public:
  void Push(__int32 &);
  void Push(__int64 &);
  void Pop(__int32 &);
  void Pop(__int64 &);
} stack;

ptrdiff_t value_1;
stack.Push(value_1);
...
int value_2;
stack.Pop(value_2);

A careless programmer placed and then chose form the stack of values of different types (ptrdiff_t and int). On the 32-bit system their sizes coincided and everything worked perfectly. When the size of ptrdiff_t type changes in a 64-bit program stack began to include more bytes than it extract out later.

We think you understand this kind of errors and that you should pay attention to the call of overload functions transferring actual arguments of memsize type.