Mypy plugin crashes on an assertion error #559
Description
Describe the problem.
When upgrading the extensions package to proxystore==0.6.5, I got the following mypy crash.
proxystore-extensions$ mypy proxystore_ex/plugins/distributed.py --show
-traceback
proxystore_ex/plugins/distributed.py:406: error: INTERNAL ERROR -- Please try using mypy master on GitHub:
https://mypy.readthedocs.io/en/stable/common_issues.html#using-a-development-mypy-build
Please report a bug at https://github.com/python/mypy/issues
version: 1.10.0
Traceback (most recent call last):
File "mypy/checkexpr.py", line 5760, in accept
File "mypy/nodes.py", line 1831, in accept
File "mypy/checkexpr.py", line 3243, in visit_member_expr
File "mypy/checkexpr.py", line 3264, in analyze_ordinary_member_access
File "mypy/checkmember.py", line 205, in analyze_member_access
File "mypy/checkmember.py", line 229, in _analyze_member_access
File "mypy/checkmember.py", line 466, in analyze_union_member_access
File "mypy/checkmember.py", line 224, in _analyze_member_access
File "mypy/checkmember.py", line 352, in analyze_instance_member_access
File "mypy/checkmember.py", line 573, in analyze_member_var_access
File "/home/jgpaul/workspace/proxystore-extensions/venv/lib/python3.11/site-packages/proxystore/mypy_plugin.py", line 90, in proxy_attribute_access
assert isinstance(ctx.type, Instance)
AssertionError:
proxystore_ex/plugins/distributed.py:406: : note: use --pdb to drop into pdb
The crash happens on this line: https://github.com/proxystore/extensions/blob/b0aba0fc840316e8f1a716343194d7d4d3ad2359/proxystore_ex/plugins/distributed.py#L406
In v0.6.5, __factory__ no longer exists so I'd expect a mypy error but not a crash. Fixing those lines to use get_factory() fixes the crash, but I'd like to avoid crashing entirely.
Here's a minimal reproducer:
from typing import Callable, TypeVar
from proxystore.proxy import Proxy
T = TypeVar('T')
def foo(x: T | Proxy[T]) -> T | Callable[[], T]:
if isinstance(x, Proxy):
return x.__factory__ # crashes
else:
return x
x = Proxy(lambda: 42)
x.__factory__ # errors correctly that int has no attribute __factory__The error seems specific to foo()'s parameter x being T | Proxy[T]. Removing the union and just having x: Proxy[T] makes the crash go away.
How did you install ProxyStore?
$ pip install proxystoreProxyStore Version
v0.6.5
Python Version
All
OS and Platform
All