Fix a segfault in UDP handle

uvloop/handles/handle.pxd

@@ -24,7 +24,6 @@ cdef class UVHandle:
 
     cdef _warn_unclosed(self)
 
-    cdef _dealloc_impl(self)
     cdef _free(self)
     cdef _close(self)
 

uvloop/handles/handle.pyx

@@ -26,9 +26,6 @@ cdef class UVHandle:
                 self.__class__.__name__))
 
     def __dealloc__(self):
-        self._dealloc_impl()
-
-    cdef _dealloc_impl(self):
         if UVLOOP_DEBUG:
             if self._loop is not None:
                 self._loop._debug_handles_current.subtract([
@@ -40,9 +37,6 @@ cdef class UVHandle:
                     .format(self.__class__.__name__))
 
         if self._handle is NULL:
-            if UVLOOP_DEBUG:
-                if self._has_handle == 0:
-                    self._loop._debug_uv_handles_freed += 1
             return
 
         # -> When we're at this point, something is wrong <-

uvloop/handles/process.pyx

@@ -190,7 +190,7 @@ cdef class UVProcess(UVHandle):
                 'UVProcess._close_after_spawn called after uv_spawn')
         self._fds_to_close.add(fd)
 
-    cdef _dealloc_impl(self):
+    def __dealloc__(self):
         if self.uv_opt_env is not NULL:
             PyMem_RawFree(self.uv_opt_env)
             self.uv_opt_env = NULL
@@ -199,8 +199,6 @@ cdef class UVProcess(UVHandle):
             PyMem_RawFree(self.uv_opt_args)
             self.uv_opt_args = NULL
 
-        UVHandle._dealloc_impl(self)
-
     cdef char** __to_cstring_array(self, list arr):
         cdef:
             int i

uvloop/handles/udp.pyx

@@ -100,18 +100,18 @@ cdef class UDPTransport(UVBaseTransport):
         udp._init(loop, sock, r_addr)
         return udp
 
-    cdef _dealloc_impl(self):
+    def __dealloc__(self):
+        # Cython has a weird bug when __dealloc__ is declared on
+        # the base class and calls some overloaded functions.
+        # So we duplicate __dealloc__ declaration here.
+
+        if UVLOOP_DEBUG:
+            self._loop._debug_uv_handles_freed += 1
+
         if self._closed == 0:
             self._warn_unclosed()
             self._close()
 
-        # It is unsafe to call `self.poll._close()` here as
-        # we might be at the stage where all CPython objects
-        # are being freed, and `self.poll` points to some
-        # zombie Python object.  So we do nothing.
-
-        UVHandle._dealloc_impl(self)
-
     cdef _free(self):
         if self.poll is not None:
             self.poll._close()