fix: #517 special handling of typing module

dill/_dill.py

@@ -196,6 +196,7 @@ def get_file_type(*args, **kwargs):
 
 import inspect
 import dataclasses
+import typing
 
 from pickle import GLOBAL
 
@@ -761,6 +762,13 @@ def _create_ftype(ftypeobj, func, args, kwds):
         args = ()
     return ftypeobj(func, *args, **kwds)
 
+def _create_typing_tuple(argz, *args): #NOTE: workaround python bug
+    if not argz:
+        return typing.Tuple[()].copy_with(())
+    if argz == ((),):
+        return typing.Tuple[()]
+    return typing.Tuple[argz]
+
 def _create_lock(locked, *args): #XXX: ignores 'blocking'
     from threading import Lock
     lock = Lock()
@@ -1276,6 +1284,23 @@ def save_classobj(pickler, obj): #FIXME: enable pickler._byref
         logger.trace(pickler, "# C2")
     return
 
+@register(typing._GenericAlias)
+def save_generic_alias(pickler, obj):
+    args = obj.__args__
+    if type(obj.__reduce__()) is str:
+        logger.trace(pickler, "Ga0: %s", obj)
+        StockPickler.save_global(pickler, obj, name=obj.__reduce__())
+        logger.trace(pickler, "# Ga0")
+    elif obj.__origin__ is tuple and (not args or args == ((),)):
+        logger.trace(pickler, "Ga1: %s", obj)
+        pickler.save_reduce(_create_typing_tuple, (args,), obj=obj)
+        logger.trace(pickler, "# Ga1")
+    else:
+        logger.trace(pickler, "Ga2: %s", obj)
+        StockPickler.save_reduce(pickler, *obj.__reduce__(), obj=obj)
+        logger.trace(pickler, "# Ga2")
+    return
+
 @register(LockType)
 def save_lock(pickler, obj):
     logger.trace(pickler, "Lo: %s", obj)

dill/tests/test_selected.py

@@ -98,9 +98,26 @@ def test_frame_related():
   assert ok
   if verbose: print ("")
 
+def test_typing():
+  import typing #FIXME: test special cases
+  x = typing.Dict[int, str]
+  assert x == dill.copy(x)
+  x = typing.List[int]
+  assert x == dill.copy(x)
+  x = typing.Tuple[int, str]
+  assert x == dill.copy(x)
+  x = typing.Tuple[int]
+  assert x == dill.copy(x)
+  x = typing.Tuple[()]
+  assert x == dill.copy(x)
+  x = typing.Tuple[()].copy_with(())
+  assert x == dill.copy(x)
+  return
+
 
 if __name__ == '__main__':
   test_frame_related()
   test_dict_contents()
   test_class()
   test_class_descriptors()
+  test_typing()