Recursion error with nested Union #9657
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That's fun; I can repro. Thanks for the clear report. |
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Not that this isn't a bug, but note that Iterator is a subclass of Iterable (https://github.com/python/typeshed/blob/master/stdlib/3/typing.pyi#L177; every Iterator is also an Iterable), so the Union in your original example is redundant. |
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Thank you @JelleZijlstra. If I had checked collections.abc I would have seen this too, I feel like a bit of a numpty now. Thank you I'll shift over to that. Tests to check Iterable = Iterdef foo_list() -> Iterable[int]:
return [0]
def foo_set() -> Iterable[int]:
return {0}
def foo_dict() -> Iterable[int]:
return {0: 'a'}
def foo_iterator() -> Iterable[int]:
yield 0
def bar(foo: Iterable[int]) -> None:
pass
bar([0])
bar({0})
bar({0: 'a'})
bar(iter([0]))In light of this I tested changing to from typing import Union, Iterator, Iterable
def bar(
values: Union[
Iterable[Union[
Iterable[Union[Iterable[int], Iterator[int]]],
Iterator[Union[Iterable[int], Iterator[int]]],
]],
Iterator[Union[
Iterable[Union[Iterable[int], Iterator[int]]],
Iterator[Union[Iterable[int], Iterator[int]]],
]],
]
) -> Iterator[int]:
for i in values:
for j in i:
for k in j:
yield k
bar([[[1]]]) |
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Crash Report
Many of my functions take
Iter = Union[Iterator[T], Iterable[T]]as arguments. Asforand many other functions in Python work with both iterators and iterables. However when I useIter[Iter[T]]the code can break.I've used
Iter[Iter[Iter[int]]]as an example asIter[Iter[T]]didn't break locally on the MVCE. Possibly due to a smaller existing stack.Traceback
Traceback - it's long
To Reproduce
Playground. However, I'm not sure if these are the same errors. My local mypy results in a status 2 where the playground has status 139.
Existing issues
This error seems related to #6730 however the tracebacks are different. Whilst the crashes may be related I think this shows that the current code is exponential leading to crashes.
My recursive traceback
6730 recursive traceback
Caching
The error seems somewhat tempermental. If
baris proceeded with a subset of the type it seems some caching comes in to play. This runs without error.The text was updated successfully, but these errors were encountered: