[red-knot] Assignability for subclasses of Any and Unknown#17557
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[red-knot] Assignability for subclasses of Any and Unknown#17557
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sharkdp
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sharkdp
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AlexWaygood
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This LGTM, though I'd also include Unknown, and I think making some exceptions for @final classes does make sense.
It's unrelated to your PR, but while we're here: I find the comment at the top of this is_assignable_to method slightly confusing. I'm not sure what it's trying to say (or why); I'd be inclined to just delete it?
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## Summary We currently emit a diagnostic for code like the following: ```py from typing import Any # error: Invalid class base with type `GenericAlias` (all bases must be a class, `Any`, `Unknown` or `Todo`) class C(tuple[Any, ...]): ... ``` The changeset here silences this diagnostic by recognizing instances of `GenericAlias` in `ClassBase::try_from_type`, and inferring a `@Todo` type for them. This is a change in preparation for #17557, because `C` previously had `Unknown` in its MRO … ```py reveal_type(C.__mro__) # tuple[Literal[C], Unknown, Literal[object]] ``` … which would cause us to think that `C` is assignable to everything. The changeset also removes some false positive `invalid-base` diagnostics across the ecosystem. ## Test Plan Updated Markdown tests.
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Any and Unknown
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With the new changes, we also allow subclasses of # This is a union with Unknown, because `IOError` is a
# simple `IOError = OSError` type alias in typeshed
reveal_type(IOError) # Unknown | Literal[OSError]
class MyError(IOError): ...
reveal_type(MyError.__mro__) # tuple[Literal[MyError], Unknown, Literal[object]]
raise MyError() # no invalid-raise diagnostic anymorewe still raise "Invalid class base with type |
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* main: (28 commits) [red-knot] Make `BoundMethodType` a salsa interned (#17581) [red-knot] Emit a diagnostic if a non-protocol is passed to `get_protocol_members` (#17551) [red-knot] Add more tests for protocol members (#17550) [red-knot] Assignability for subclasses of `Any` and `Unknown` (#17557) [red-knot] mypy_primer: add strawberry, print compilation errors to stderr (#17578) [red-knot] GenericAlias instances as a base class (#17575) Remove redundant `type_to_visitor_function` entries (#17564) Fixes how the checker visits `typing.cast`/`typing.NewType` arguments (#17538) [red-knot] Class literal `__new__` function callable subtyping (#17533) [red-knot] Surround intersections with `()` in potentially ambiguous contexts (#17568) [minor] Delete outdated TODO comment (#17565) [red-knot] add regression test for fixed cycle panic (#17535) [red-knot] fix unions of literals, again (#17534) red_knot_python_semantic: remove last vestige of old diagnostics! red_knot_python_semantic: migrate `types` to new diagnostics red_knot_python_semantic: migrate `types/diagnostic` to new diagnostics red_knot_python_semantic: migrate `types/call/bind` to new diagnostics red_knot_python_semantic: migrate `types/string_annotation` to new diagnostics red_knot_python_semantic: migrate `types/infer` to new diagnostic model red_knot_python_semantic: migrate INVALID_ASSIGNMENT for inference ...
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…var-instance * dcreager/generic-constructor: (29 commits) We don't need this [red-knot] Make `BoundMethodType` a salsa interned (#17581) [red-knot] Emit a diagnostic if a non-protocol is passed to `get_protocol_members` (#17551) [red-knot] Add more tests for protocol members (#17550) [red-knot] Assignability for subclasses of `Any` and `Unknown` (#17557) [red-knot] mypy_primer: add strawberry, print compilation errors to stderr (#17578) [red-knot] GenericAlias instances as a base class (#17575) Remove redundant `type_to_visitor_function` entries (#17564) Fixes how the checker visits `typing.cast`/`typing.NewType` arguments (#17538) [red-knot] Class literal `__new__` function callable subtyping (#17533) [red-knot] Surround intersections with `()` in potentially ambiguous contexts (#17568) [minor] Delete outdated TODO comment (#17565) [red-knot] add regression test for fixed cycle panic (#17535) [red-knot] fix unions of literals, again (#17534) red_knot_python_semantic: remove last vestige of old diagnostics! red_knot_python_semantic: migrate `types` to new diagnostics red_knot_python_semantic: migrate `types/diagnostic` to new diagnostics red_knot_python_semantic: migrate `types/call/bind` to new diagnostics red_knot_python_semantic: migrate `types/string_annotation` to new diagnostics red_knot_python_semantic: migrate `types/infer` to new diagnostic model ...
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Summary
Allow (instances of) subclasses of
AnyandUnknownto be assignable to (instances of) other classes, unless they are final. This allows us to get rid of ~1000 false positives, mostly when mock-objects likeunittest.mock.MagicMockare assigned to various targets.Test Plan
Adapted and new Markdown tests.