fix condition to make struct conversion generate struct field conversion helpers at need

--HG--
extra : amend_source : 240f49031159777036e1e6a139b6d736f59de337

Cython/Compiler/PyrexTypes.py

@@ -2842,7 +2842,7 @@ class CStructOrUnionType(CType):
 
         if self._convert_to_py_code is None:
             for member in self.scope.var_entries:
-                if not member.type.to_py_function or not member.type.create_to_py_utility_code(env):
+                if not member.type.to_py_function and not member.type.create_to_py_utility_code(env):
                     self.to_py_function = None
                     self._convert_to_py_code = False
                     return False
@@ -2860,7 +2860,7 @@ class CStructOrUnionType(CType):
 
         if self._convert_from_py_code is None:
             for member in self.scope.var_entries:
-                if (not member.type.from_py_function or not
+                if (not member.type.from_py_function and not
                         member.type.create_from_py_utility_code(env)):
                     self.from_py_function = None
                     self._convert_from_py_code = False