AttributeError: module 'typing' has no attribute '_ClassVar'

[yllgl]

🐛 Bug

After I upgrade my pytorch_lightning version to 1.3.5, this error occurs when I try to import pytorch_lightning in my code.

Environment

• CUDA:
  - GPU:
  - Tesla K80
  - Tesla K80
  - Tesla K80
  - Tesla K80
  - available: True
  - version: 10.2
• Packages:
  - numpy: 1.19.4
  - pyTorch_debug: True
  - pyTorch_version: 1.7.0
  - pytorch-lightning: 1.3.5
  - tqdm: 4.47.0
• System:
  - OS: Linux
  - architecture:
  - 64bit
  - ELF
  - processor: x86_64
  - python: 3.8.3
  - version: Thanks for sharing! #2 SMP Mon Apr 23 15:52:50 CST 2018

Additional context

Python 3.8.3 (default, Jul  2 2020, 16:21:59)
[GCC 7.3.0] :: Anaconda, Inc. on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pytorch_lightning
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/__init__.py", line 21, in <module>
    from pytorch_lightning.callbacks import Callback  # noqa: E402
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/callbacks/__init__.py", line 26, in <module>
    from pytorch_lightning.callbacks.stochastic_weight_avg import StochasticWeightAveraging
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/callbacks/stochastic_weight_avg.py", line 26, in <module>
    from pytorch_lightning.trainer.optimizers import _get_default_scheduler_config
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/trainer/__init__.py", line 18, in <module>
    from pytorch_lightning.trainer.trainer import Trainer
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/trainer/trainer.py", line 25, in <module>
    from pytorch_lightning.accelerators import Accelerator
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/accelerators/__init__.py", line 13, in <module>
    from pytorch_lightning.accelerators.accelerator import Accelerator  # noqa F401
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/accelerators/accelerator.py", line 25, in <module>
    from pytorch_lightning.plugins.precision import ApexMixedPrecisionPlugin, NativeMixedPrecisionPlugin, PrecisionPlugin
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/plugins/__init__.py", line 2, in <module>
    from pytorch_lightning.plugins.plugins_registry import (  # noqa: F401
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/plugins/plugins_registry.py", line 21, in <module>
 from pytorch_lightning.trainer.optimizers import _get_default_scheduler_config
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/trainer/__init__.py", line 18, in <module>
    from pytorch_lightning.trainer.trainer import Trainer
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/trainer/trainer.py", line 25, in <module>
    from pytorch_lightning.accelerators import Accelerator
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/accelerators/__init__.py", line 13, in <module>
    from pytorch_lightning.accelerators.accelerator import Accelerator  # noqa F401
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/accelerators/accelerator.py", line 25, in <module>
    from pytorch_lightning.plugins.precision import ApexMixedPrecisionPlugin, NativeMixedPrecisionPlugin, PrecisionPlugin
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/plugins/__init__.py", line 2, in <module>
    from pytorch_lightning.plugins.plugins_registry import (  # noqa: F401
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/plugins/plugins_registry.py", line 21, in <module>
    from pytorch_lightning.plugins.training_type.training_type_plugin import TrainingTypePlugin
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/plugins/training_type/__init__.py", line 3, in <module>
    from pytorch_lightning.plugins.training_type.ddp_spawn import DDPSpawnPlugin  # noqa: F401
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/plugins/training_type/ddp_spawn.py", line 30, in <module>
    from pytorch_lightning.trainer.states import TrainerFn
  File "/THL5/home/hugpu1/.local/lib/python3.8/site-packages/pytorch_lightning/trainer/states.py", line 80, in <module>
    class TrainerState:
  File "/THL5/software/pytorch/1.7.0-cu102-py38/dataclasses.py", line 958, in dataclass
    return wrap(_cls)
  File "/THL5/software/pytorch/1.7.0-cu102-py38/dataclasses.py", line 950, in wrap
    return _process_class(cls, init, repr, eq, order, unsafe_hash, frozen)
  File "/THL5/software/pytorch/1.7.0-cu102-py38/dataclasses.py", line 800, in _process_class
    cls_fields = [_get_field(cls, name, type)
  File "/THL5/software/pytorch/1.7.0-cu102-py38/dataclasses.py", line 800, in <listcomp>
    cls_fields = [_get_field(cls, name, type)
  File "/THL5/software/pytorch/1.7.0-cu102-py38/dataclasses.py", line 659, in _get_field
    if (_is_classvar(a_type, typing)
  File "/THL5/software/pytorch/1.7.0-cu102-py38/dataclasses.py", line 550, in _is_classvar
    return type(a_type) is typing._ClassVar
AttributeError: module 'typing' has no attribute '_ClassVar'

[yllgl]

I upgrade pytorch version and it solves my problem.