[ty] Fix descriptor lookups for most types that overlap with `None` by AlexWaygood · Pull Request #19120 · astral-sh/ruff

AlexWaygood · 2025-07-03T13:22:57Z

Summary

Helps with astral-sh/ty#737. The problem remains for calling methods on None itself, but no longer applies to object, AlwaysTruthy, AlwaysFalsy, or protocols that are not disjoint from None.

Test Plan

mdtests

github-actions · 2025-07-03T13:26:41Z

`mypy_primer` results

Changes were detected when running on open source projects

parso (https://github.com/davidhalter/parso)
-     memo fields = ~54MB
+     memo fields = ~49MB

async-utils (https://github.com/mikeshardmind/async-utils)
- TOTAL MEMORY USAGE: ~45MB
+ TOTAL MEMORY USAGE: ~49MB

beartype (https://github.com/beartype/beartype)
- TOTAL MEMORY USAGE: ~88MB
+ TOTAL MEMORY USAGE: ~97MB

werkzeug (https://github.com/pallets/werkzeug)
- error[non-subscriptable] src/werkzeug/utils.py:91:13: Cannot subscript object of type `property` with no `__getitem__` method
+ error[non-subscriptable] src/werkzeug/utils.py:91:13: Cannot subscript object of type `object` with no `__getitem__` method
- error[non-subscriptable] src/werkzeug/utils.py:118:17: Cannot subscript object of type `property` with no `__getitem__` method
+ error[non-subscriptable] src/werkzeug/utils.py:118:17: Cannot subscript object of type `object` with no `__getitem__` method

discord.py (https://github.com/Rapptz/discord.py)
-     memo fields = ~189MB
+     memo fields = ~207MB

rich (https://github.com/Textualize/rich)
-     memo fields = ~117MB
+     memo fields = ~106MB

isort (https://github.com/pycqa/isort)
-     memo metadata = ~5MB
+     memo metadata = ~6MB

pylox (https://github.com/sco1/pylox)
-     memo fields = ~49MB
+     memo fields = ~54MB

poetry (https://github.com/python-poetry/poetry)
-     memo fields = ~189MB
+     memo fields = ~171MB

jinja (https://github.com/pallets/jinja)
-     memo fields = ~80MB
+     memo fields = ~88MB

pytest (https://github.com/pytest-dev/pytest)
- TOTAL MEMORY USAGE: ~276MB
+ TOTAL MEMORY USAGE: ~251MB

vision (https://github.com/pytorch/vision)
- error[missing-argument] torchvision/datasets/vision.py:81:17: No argument provided for required parameter `self` of function `__repr__`
- error[missing-argument] torchvision/datasets/vision.py:101:17: No argument provided for required parameter `self` of function `__repr__`
- Found 1474 diagnostics
+ Found 1472 diagnostics

psycopg (https://github.com/psycopg/psycopg)
-     memo metadata = ~25MB
+     memo metadata = ~28MB

openlibrary (https://github.com/internetarchive/openlibrary)
-     memo fields = ~171MB
+     memo fields = ~189MB

bokeh (https://github.com/bokeh/bokeh)
- TOTAL MEMORY USAGE: ~251MB
+ TOTAL MEMORY USAGE: ~276MB

prefect (https://github.com/PrefectHQ/prefect)
- error[missing-argument] src/prefect/settings/legacy.py:80:16: No argument provided for required parameter `value` of function `__eq__`
- Found 3753 diagnostics
+ Found 3752 diagnostics

scipy (https://github.com/scipy/scipy)
- TOTAL MEMORY USAGE: ~1399MB
+ TOTAL MEMORY USAGE: ~1271MB

AlexWaygood · 2025-07-03T13:33:53Z

crates/ty_python_semantic/src/types.rs

                                    .with_annotated_type(descriptor),
                                Parameter::positional_only(Some(Name::new_static("instance")))
-                                    .with_annotated_type(not_none),
+                                    .with_annotated_type(Type::object(db)),


this means that we now selected overload 2 rather than overload 1 for types such as object that are not subtypes of None, but are also not disjoint from None

crates/ty_python_semantic/resources/mdtest/descriptor_protocol.md

sharkdp · 2025-07-03T17:45:20Z

crates/ty_python_semantic/src/types.rs

                // TODO: Consider merging this signature with the one in the previous match clause,
                // since the previous one is just this signature with the `self` parameters
                // removed.
-                let not_none = Type::none(db).negate(db);


I think you may want to apply the same change to the match case just above, right? It's slightly harder to write a test for, because you might need to call __get__ manually? Let me know if you need help.

thanks, yes, you're correct that we emitted false positive diagnostics for object.__str__.__get__(object(), None)() as well as object().__str__() 😆

I added a regression test!

object.__str__.__get__(object(), None)()

Just imagine how happy users will be that this finally works correctly.

AlexWaygood added the ty Multi-file analysis & type inference label Jul 3, 2025

AlexWaygood marked this pull request as ready for review July 3, 2025 13:28

AlexWaygood requested review from carljm, dcreager and sharkdp as code owners July 3, 2025 13:28

AlexWaygood commented Jul 3, 2025

View reviewed changes

AlexWaygood added the bug Something isn't working label Jul 3, 2025

carljm approved these changes Jul 3, 2025

View reviewed changes

crates/ty_python_semantic/resources/mdtest/descriptor_protocol.md Outdated Show resolved Hide resolved

sharkdp reviewed Jul 3, 2025

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AlexWaygood added 2 commits July 5, 2025 19:20

[ty] Fix descriptor lookups for most types that overlap with None

c1164cc

fix explicit calls to __get__ also

d69aab4

AlexWaygood force-pushed the alex/none-descr branch from 5f26ed4 to d69aab4 Compare July 5, 2025 18:29

AlexWaygood merged commit 08d8819 into main Jul 5, 2025
35 checks passed

AlexWaygood deleted the alex/none-descr branch July 5, 2025 18:34

This was referenced Jul 5, 2025

Incorrect descriptor lookup for methods on types that are not disjoint from None astral-sh/ty#737

Closed

Draft for negation types article JelleZijlstra/JelleZijlstra.github.io#17

Merged

sharkdp mentioned this pull request Feb 12, 2026

[ty] Fix bound method access on None #23246

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[ty] Fix descriptor lookups for most types that overlap with `None`#19120

[ty] Fix descriptor lookups for most types that overlap with `None`#19120
AlexWaygood merged 2 commits intomainfrom
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AlexWaygood commented Jul 3, 2025 •

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