Add nullptr to libcpp declarations.

Cython/Includes/libcpp/__init__.pxd

 cdef extern from *:
     ctypedef bint bool
+    ctypedef void* nullptr_t
+    nullptr_t nullptr

Cython/Includes/libcpp/memory.pxd

-from libcpp cimport bool
-    
+from libcpp cimport bool, nullptr_t, nullptr
+
 cdef extern from "<memory>" namespace "std" nogil:
-    ctypedef void* nullptr_t; # Should be decltype(nullptr)
-    
+
     cdef cppclass unique_ptr[T]:
         unique_ptr()
         unique_ptr(nullptr_t)
         unique_ptr(T*)
         unique_ptr(unique_ptr[T]&)
-        
+
         # Modifiers
         T* release()
         void reset()
         void reset(nullptr_t)
         void reset(T*)
         void swap(unique_ptr&)
-        
+
         # Observers
         T* get()
         T& operator*()
         #T* operator->() # Not Supported
         #bool operator bool() # Not Supported
-        
+
         bool operator==(const unique_ptr&)
         bool operator!=(const unique_ptr&)
         bool operator<(const unique_ptr&)
         bool operator>(const unique_ptr&)
         bool operator<=(const unique_ptr&)
         bool operator>=(const unique_ptr&)
-        
+
         bool operator==(nullptr_t)
         bool operator!=(nullptr_t)
-    
+
     # Forward Declaration not working ("Compiler crash in AnalyseDeclarationsTransform")
     #cdef cppclass weak_ptr[T]
-    
+
     cdef cppclass shared_ptr[T]:
         shared_ptr()
         shared_ptr(nullptr_t)
@@ -43,12 +42,12 @@ cdef extern from "<memory>" namespace "std" nogil:
         shared_ptr(shared_ptr[T]&, T*)
         shared_ptr(unique_ptr[T]&)
         #shared_ptr(weak_ptr[T]&) # Not Supported
-        
+
         # Modifiers
         void reset()
         void reset(T*)
         void swap(shared_ptr&)
-        
+
         # Observers
         T* get()
         T& operator*()
@@ -58,26 +57,26 @@ cdef extern from "<memory>" namespace "std" nogil:
         #bool operator bool() # Not Supported
         #bool owner_before[Y](const weak_ptr[Y]&) # Not Supported
         bool owner_before[Y](const shared_ptr[Y]&)
-        
+
         bool operator==(const shared_ptr&)
         bool operator!=(const shared_ptr&)
         bool operator<(const shared_ptr&)
         bool operator>(const shared_ptr&)
         bool operator<=(const shared_ptr&)
         bool operator>=(const shared_ptr&)
-        
+
         bool operator==(nullptr_t)
         bool operator!=(nullptr_t)
-    
+
     cdef cppclass weak_ptr[T]:
         weak_ptr()
         weak_ptr(weak_ptr[T]&)
         weak_ptr(shared_ptr[T]&)
-        
+
         # Modifiers
         void reset()
         void swap(weak_ptr&)
-        
+
         # Observers
         long use_count()
         bool expired()