Mixing generic container from typing and built-in crashes on py3.7-8 #218
Description
- cattrs version: 22.1.0dev0
- Python version: 3.7, 3.8 (FAILS) 3.9, 3.10 (OK)
- Operating System: irrelevant
Description
Specifying an empty generic type from a standard library - so far tested on dict and list - crashes, since these types do not have __args__ attribute until py3.9
Python 3.8.10 (default, Nov 26 2021, 20:14:08)
[GCC 9.3.0] on linux
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>>> import typing as t
>>>
>>> import attrs
>>> import cattrs
>>>
>>> @attrs.define
... class A1:
... bs: t.List[dict]
...
>>> @attrs.define
... class A2:
... bs: t.List[list]
...
>>> @attrs.define
... class D:
... d: dict
...
>>> cattrs.structure({"bs": [{}, {"a": 1}]}, A1)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/converters.py", line 300, in structure
return self._structure_func.dispatch(cl)(obj, cl)
File "<cattrs generated structure __main__.A1>", line 3, in structure_A1
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/converters.py", line 478, in _structure_list
return [
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/converters.py", line 479, in <listcomp>
self._structure_func.dispatch(elem_type)(e, elem_type)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/dispatch.py", line 49, in _dispatch
return self._function_dispatch.dispatch(cl)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/dispatch.py", line 126, in dispatch
return handler(typ)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/converters.py", line 790, in gen_structure_mapping
h = make_mapping_structure_fn(cl, self)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/gen.py", line 465, in make_mapping_structure_fn
if not is_bare(cl):
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/_compat.py", line 171, in is_bare
args = type.__args__
AttributeError: type object 'dict' has no attribute '__args__'
>>> cattrs.structure({"bs": [[], [1]]}, A2)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/converters.py", line 300, in structure
return self._structure_func.dispatch(cl)(obj, cl)
File "<cattrs generated structure __main__.A2>", line 3, in structure_A2
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/converters.py", line 478, in _structure_list
return [
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/converters.py", line 479, in <listcomp>
self._structure_func.dispatch(elem_type)(e, elem_type)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/converters.py", line 474, in _structure_list
if is_bare(cl) or cl.__args__[0] is Any:
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/_compat.py", line 171, in is_bare
args = type.__args__
AttributeError: type object 'list' has no attribute '__args__'
>>>
>>> cattrs.structure({"d": {}}, D)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/converters.py", line 300, in structure
return self._structure_func.dispatch(cl)(obj, cl)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/dispatch.py", line 49, in _dispatch
return self._function_dispatch.dispatch(cl)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/dispatch.py", line 126, in dispatch
return handler(typ)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/converters.py", line 740, in gen_structure_attrs_fromdict
h = make_dict_structure_fn(
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/gen.py", line 280, in make_dict_structure_fn
handler = converter._structure_func.dispatch(t)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/dispatch.py", line 49, in _dispatch
return self._function_dispatch.dispatch(cl)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/dispatch.py", line 126, in dispatch
return handler(typ)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/converters.py", line 790, in gen_structure_mapping
h = make_mapping_structure_fn(cl, self)
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/gen.py", line 465, in make_mapping_structure_fn
if not is_bare(cl):
File "/home/libor/.virtualenvs/cattrs/lib/python3.8/site-packages/cattr/_compat.py", line 171, in is_bare
args = type.__args__
AttributeError: type object 'dict' has no attribute '__args__'
Swapping dict/list for their upper-cased variants produces expected behaviour
>>> @attrs.define
... class D2:
... d: typing.Dict
...
>>>
>>> cattrs.structure({"d": {}}, D2)
D2(d={})