New submission from Kefei Lu <klu...@gmail.com>:
This is a new regression in Python3.7.
Create the following file as `test.py`
```
# test.py
import typing as t
T = t.TypeVar("T")
class BaseOfGeneric:
@classmethod
def f(cls):
# when called from an instantiated generic type, e.g.,
# `MyList[int]`, expect `cls` to be the GenericAlias with its type
# argument already insteantiated
print(f"current class is {cls}")
print(f"current class's type: {type(cls)}")
class MyList(t.List[T], BaseOfGeneric):
pass
MyIntList = MyList[int]
MyIntList.f()
```
Run with Python3.6:
>>> python3.6 ./test.py
current class is __main__.MyList[int]
^^^ as expected
current class's type: <class 'typing.GenericMeta'>
EXPECTED BEHAVIOR: The outcome is expected: `cls` of `BaseOfGeneric.f` should
be `MyList` **with** type argument `int`
However this is wrong in Python3.7:
>>> python3.7 ./test.py
current class is <class '__main__.MyList'>
^^^^^^^^^^^^^^^ type argument is LOST !!!
current class's type: <class 'type'>
Note that `cls` of `BaseOfGeneric.f` has lost the type argument `int`! It is
not expected.
----------
messages: 353386
nosy: kflu
priority: normal
severity: normal
status: open
title: Base class of generic type has wrong `cls` argument in classmethods
type: behavior
versions: Python 3.7
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue38298>
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