[ty] Diagnostics for async context managers #19704

silamon · 2025-08-02T12:00:50Z

Summary

Implements diagnostics for async context managers. Fixes astral-sh/ty#918.

Test Plan

Mdtests have been added.

github-actions · 2025-08-02T12:08:04Z

Diagnostic diff on typing conformance tests

Changes were detected when running ty on typing conformance tests

--- old-output.txt	2025-08-05 06:55:05.191000775 +0000
+++ new-output.txt	2025-08-05 06:55:05.252000918 +0000
@@ -137,6 +137,7 @@
 callables_annotation.py:57:18: error[invalid-type-form] List literals are not allowed in this context in a type expression: Did you mean `list[int]`?
 callables_annotation.py:58:5: error[invalid-type-form] Special form `typing.Callable` expected exactly two arguments (parameter types and return type)
 callables_annotation.py:58:14: error[invalid-type-form] The first argument to `Callable` must be either a list of types, ParamSpec, Concatenate, or `...`
+callables_annotation.py:114:14: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Protocol`
 callables_kwargs.py:24:5: error[type-assertion-failure] Argument does not have asserted type `int`
 callables_kwargs.py:32:9: error[type-assertion-failure] Argument does not have asserted type `str`
 callables_kwargs.py:35:5: error[type-assertion-failure] Argument does not have asserted type `str`
@@ -147,9 +148,12 @@
 callables_kwargs.py:65:5: error[missing-argument] No argument provided for required parameter `v3` of function `func2`
 callables_protocol.py:97:1: error[invalid-assignment] Object of type `def cb4_bad1(x: int) -> None` is not assignable to `Proto4`
 callables_protocol.py:121:1: error[invalid-assignment] Object of type `def cb6_bad1(*vals: bytes, *, max_len: int | None = None) -> list[bytes]` is not assignable to `NotProto6`
+callables_protocol.py:176:14: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Protocol`
 callables_protocol.py:179:62: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `R@__call__`
 callables_subtyping.py:26:5: error[invalid-assignment] Object of type `(int, /) -> int` is not assignable to `(int | float, /) -> int | float`
 callables_subtyping.py:29:5: error[invalid-assignment] Object of type `(int | float, /) -> int | float` is not assignable to `(int, /) -> int`
+callables_subtyping.py:204:21: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Protocol`
+classes_classvar.py:35:14: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Generic`
 classes_classvar.py:38:11: error[invalid-type-form] Type qualifier `typing.ClassVar` expected exactly 1 argument, got 2
 classes_classvar.py:39:14: error[invalid-type-form] Int literals are not allowed in this context in a type expression
 classes_classvar.py:40:14: error[unresolved-reference] Name `var` used when not defined
@@ -382,6 +386,7 @@
 generics_defaults.py:55:1: error[type-assertion-failure] Argument does not have asserted type `@Todo`
 generics_defaults.py:59:1: error[type-assertion-failure] Argument does not have asserted type `@Todo`
 generics_defaults.py:63:1: error[type-assertion-failure] Argument does not have asserted type `@Todo`
+generics_defaults.py:76:23: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Generic`
 generics_defaults.py:79:1: error[type-assertion-failure] Argument does not have asserted type `@Todo`
 generics_defaults.py:80:1: error[type-assertion-failure] Argument does not have asserted type `@Todo`
 generics_defaults.py:91:26: error[invalid-argument-type] `@Todo` is not a valid argument to `Generic`
@@ -412,6 +417,7 @@
 generics_paramspec_semantics.py:38:28: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `int`
 generics_paramspec_semantics.py:53:34: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `int`
 generics_paramspec_semantics.py:57:34: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `int`
+generics_paramspec_semantics.py:67:9: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Generic`
 generics_paramspec_semantics.py:76:30: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `str`
 generics_paramspec_semantics.py:82:5: error[type-assertion-failure] Argument does not have asserted type `@Todo`
 generics_paramspec_semantics.py:82:28: error[invalid-type-form] List literals are not allowed in this context in a type expression: Did you mean `list[int]`?
@@ -424,9 +430,12 @@
 generics_paramspec_semantics.py:133:23: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `int`
 generics_paramspec_semantics.py:138:29: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `int`
 generics_paramspec_semantics.py:143:25: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `int`
+generics_paramspec_specialization.py:13:14: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Generic`
+generics_paramspec_specialization.py:18:29: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Generic`
 generics_paramspec_specialization.py:32:27: error[invalid-type-form] List literals are not allowed in this context in a type expression: Did you mean `tuple[int, bool]`?
 generics_paramspec_specialization.py:40:27: error[invalid-type-form] List literals are not allowed in this context in a type expression: Did you mean `tuple[()]`?
 generics_paramspec_specialization.py:40:31: error[invalid-type-form] List literals are not allowed in this context in a type expression: Did you mean `tuple[()]`?
+generics_paramspec_specialization.py:48:14: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Generic`
 generics_paramspec_specialization.py:52:22: error[invalid-type-form] List literals are not allowed in this context in a type expression: Did you mean `tuple[int, str, bool]`?
 generics_scoping.py:14:1: error[type-assertion-failure] Argument does not have asserted type `int`
 generics_scoping.py:15:1: error[type-assertion-failure] Argument does not have asserted type `str`
@@ -523,30 +532,23 @@
 generics_type_erasure.py:40:16: error[invalid-argument-type] Argument to bound method `__init__` is incorrect: Expected `str | None`, found `Literal[0]`
 generics_type_erasure.py:47:1: error[type-assertion-failure] Argument does not have asserted type `int`
 generics_type_erasure.py:56:1: error[type-assertion-failure] Argument does not have asserted type `bytes`
-generics_typevartuple_args.py:16:34: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[@Todo, ...]`
 generics_typevartuple_args.py:20:1: error[type-assertion-failure] Argument does not have asserted type `tuple[int, str]`
-generics_typevartuple_args.py:27:77: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[@Todo, ...]`
 generics_typevartuple_args.py:31:1: error[type-assertion-failure] Argument does not have asserted type `tuple[()]`
 generics_typevartuple_args.py:32:1: error[type-assertion-failure] Argument does not have asserted type `tuple[int, str]`
 generics_typevartuple_basic.py:12:14: error[invalid-argument-type] `@Todo` is not a valid argument to `Generic`
-generics_typevartuple_basic.py:16:26: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[@Todo, ...]`
 generics_typevartuple_basic.py:23:13: error[invalid-argument-type] `@Todo` is not a valid argument to `Generic`
-generics_typevartuple_basic.py:42:34: error[invalid-argument-type] Argument to bound method `__init__` is incorrect: Expected `tuple[@Todo, ...]`, found `Literal[1]`
+generics_typevartuple_basic.py:52:14: error[invalid-argument-type] `TypeVarTuple` is not a valid argument to `Generic`
 generics_typevartuple_basic.py:65:27: error[unknown-argument] Argument `covariant` does not match any known parameter of function `__new__`
 generics_typevartuple_basic.py:66:27: error[too-many-positional-arguments] Too many positional arguments to function `__new__`: expected 2, got 4
 generics_typevartuple_basic.py:67:27: error[unknown-argument] Argument `bound` does not match any known parameter of function `__new__`
-generics_typevartuple_basic.py:75:50: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[@Todo, ...]`
 generics_typevartuple_basic.py:84:1: error[type-assertion-failure] Argument does not have asserted type `tuple[int]`
 generics_typevartuple_basic.py:106:14: error[invalid-argument-type] `@Todo` is not a valid argument to `Generic`
-generics_typevartuple_callable.py:29:57: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[@Todo, ...]`
 generics_typevartuple_callable.py:33:54: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[int | float | complex, str, int]`
 generics_typevartuple_callable.py:37:34: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[str]`
 generics_typevartuple_callable.py:41:1: error[type-assertion-failure] Argument does not have asserted type `tuple[str, int, int | float | complex]`
 generics_typevartuple_callable.py:42:1: error[type-assertion-failure] Argument does not have asserted type `tuple[str]`
-generics_typevartuple_callable.py:45:43: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[@Todo, ...]`
 generics_typevartuple_callable.py:49:1: error[type-assertion-failure] Argument does not have asserted type `tuple[int | float, str, int | float | complex]`
 generics_typevartuple_concat.py:22:13: error[invalid-argument-type] `@Todo` is not a valid argument to `Generic`
-generics_typevartuple_concat.py:47:42: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[@Todo, ...]`
 generics_typevartuple_concat.py:52:1: error[type-assertion-failure] Argument does not have asserted type `tuple[int, bool, str]`
 generics_typevartuple_overloads.py:16:13: error[invalid-argument-type] `@Todo` is not a valid argument to `Generic`
 generics_typevartuple_specialization.py:16:13: error[invalid-argument-type] `@Todo` is not a valid argument to `Generic`
@@ -558,14 +560,15 @@
 generics_typevartuple_specialization.py:52:5: error[type-assertion-failure] Argument does not have asserted type `tuple[str, @Todo]`
 generics_typevartuple_specialization.py:52:37: error[invalid-type-form] Tuple literals are not allowed in this context in a type expression: Did you mean `tuple[()]`?
 generics_typevartuple_specialization.py:59:14: error[invalid-argument-type] `@Todo` is not a valid argument to `Generic`
+generics_typevartuple_specialization.py:92:67: error[invalid-type-form] Variable of type `type[@Todo]` is not allowed in a type expression
 generics_typevartuple_specialization.py:93:5: error[type-assertion-failure] Argument does not have asserted type `tuple[str, int]`
 generics_typevartuple_specialization.py:94:5: error[type-assertion-failure] Argument does not have asserted type `tuple[int | float]`
 generics_typevartuple_specialization.py:95:5: error[type-assertion-failure] Argument does not have asserted type `tuple[Any, *tuple[Any, ...]]`
-generics_typevartuple_specialization.py:130:35: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[tuple[@Todo, ...], T1@func7, T2@func7]`
+generics_typevartuple_specialization.py:130:35: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[@Todo, T1@func7, T2@func7]`
 generics_typevartuple_specialization.py:135:5: error[type-assertion-failure] Argument does not have asserted type `tuple[tuple[()], str, bool]`
 generics_typevartuple_specialization.py:136:5: error[type-assertion-failure] Argument does not have asserted type `tuple[tuple[str], bool, int | float]`
 generics_typevartuple_specialization.py:137:5: error[type-assertion-failure] Argument does not have asserted type `tuple[tuple[str, bool], int | float, int]`
-generics_typevartuple_specialization.py:143:39: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[tuple[@Todo, ...], T1@func9, T2@func9, T3@func9]`
+generics_typevartuple_specialization.py:143:39: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `tuple[@Todo, T1@func9, T2@func9, T3@func9]`
 generics_typevartuple_specialization.py:148:5: error[type-assertion-failure] Argument does not have asserted type `tuple[tuple[()], str, bool, int | float]`
 generics_typevartuple_specialization.py:149:5: error[type-assertion-failure] Argument does not have asserted type `tuple[tuple[bool], str, int | float, int]`
 generics_typevartuple_specialization.py:157:5: error[type-assertion-failure] Argument does not have asserted type `tuple[*tuple[int, ...], int]`
@@ -784,6 +787,7 @@
 protocols_subtyping.py:16:6: error[call-non-callable] Cannot instantiate class `Proto1`: This call will raise `TypeError` at runtime
 protocols_subtyping.py:38:5: error[invalid-assignment] Object of type `Proto2` is not assignable to `Concrete2`
 protocols_subtyping.py:55:5: error[invalid-assignment] Object of type `Proto2` is not assignable to `Proto3`
+protocols_variance.py:84:16: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Protocol`
 protocols_variance.py:85:62: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `R@__call__`
 qualifiers_annotated.py:43:17: error[invalid-type-form] List literals are not allowed in this context in a type expression: Did you mean `tuple[int, str]`?
 qualifiers_annotated.py:44:17: error[invalid-type-form] Tuple literals are not allowed in this context in a type expression
@@ -885,4 +889,4 @@
 tuples_type_form.py:36:1: error[invalid-assignment] Object of type `tuple[Literal[1], Literal[2], Literal[3], Literal[""]]` is not assignable to `tuple[int, ...]`
 typeddicts_operations.py:60:1: error[type-assertion-failure] Argument does not have asserted type `str | None`
 typeddicts_type_consistency.py:101:1: error[invalid-assignment] Object of type `Unknown | None` is not assignable to `str`
-Found 886 diagnostics
+Found 890 diagnostics

github-actions · 2025-08-02T12:10:05Z

`mypy_primer` results

Changes were detected when running on open source projects

prefect (https://github.com/PrefectHQ/prefect)
+ src/prefect/artifacts.py:675:16: error[invalid-context-manager] Object of type `nullcontext[PrefectClient & ~AlwaysFalsy] | PrefectClient` cannot be used with `async with` because the methods `__aenter__` and `__aexit__` are possibly unbound
+ src/prefect/artifacts.py:675:40: error[invalid-assignment] Object of type `CoroutineType[Any, Any, Unknown]` is not assignable to `PrefectClient | None`
+ src/prefect/artifacts.py:689:15: warning[possibly-unbound-attribute] Attribute `update_artifact` on type `PrefectClient | None` is possibly unbound
- Found 3838 diagnostics
+ Found 3841 diagnostics

No memory usage changes detected ✅

sharkdp

Thank you very much — this is great!

Only two minor comments. And we should probably take a look at the three new diagnostics in the ecosystem (see mypy_primer results PR comment)

crates/ty_python_semantic/resources/mdtest/with/async.md

...apshots/async.md_-_Async_with_statement…_-_Accidental_use_of_no…_(517649917c6efb00).snap.new

silamon · 2025-08-04T19:29:41Z

Everything CI-wise should be expected to pass right now.

carljm · 2025-08-05T03:14:30Z

Looks like tests are still failing due to a stray .snap file that isn't referenced by any test -- that needs to be removed.

carljm · 2025-08-05T14:40:47Z

This looks good to me, merging.

I reviewed the ecosystem hit and it looks like a true positive: nullcontext in Python 3.9 (which is the minimum supported version in the prefect pyproject.toml) does not implement __aenter__ or __aexit__. Switching to asyncnullcontext (also imported in that file) fixes the diagnostic. (The other two diagnostics are just cascading impact of not getting an accurate return type from __aenter__; if we want to avoid that, maybe we should infer simply Unknown instead of CoroutineType[Any, Any, Unknown] from a failed __aenter__ call, but that seems like a separate issue.)

The other issue I notice from looking at this ecosystem hit is that our diagnostics for failed dunder calls on union types could be better, but that issue pre-exists this PR and doesn't need to be fixed here; I filed astral-sh/ty#940 to track that.

Diagnostics for async context managers

b459e61

silamon requested review from carljm, AlexWaygood, sharkdp and dcreager as code owners August 2, 2025 12:00

MichaReiser added ty Multi-file analysis & type inference diagnostics Related to reporting of diagnostics. labels Aug 2, 2025

resolve correctly in async context

13a14f7

sharkdp approved these changes Aug 4, 2025

View reviewed changes

crates/ty_python_semantic/resources/mdtest/with/async.md Outdated Show resolved Hide resolved

...apshots/async.md_-_Async_with_statement…_-_Accidental_use_of_no…_(517649917c6efb00).snap.new Outdated Show resolved Hide resolved

silamon added 2 commits August 4, 2025 18:48

Update based on pull request feedback

6a5e734

Correct incorrect signature message

576eba6

sharkdp self-assigned this Aug 4, 2025

Formatting

fc431f7

Remove old snapshot

eaa7271

carljm merged commit 934fd37 into astral-sh:main Aug 5, 2025
38 checks passed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

[ty] Diagnostics for async context managers #19704

[ty] Diagnostics for async context managers #19704

Uh oh!

silamon commented Aug 2, 2025 •

edited

Loading

Uh oh!

github-actions bot commented Aug 2, 2025 •

edited

Loading

Uh oh!

github-actions bot commented Aug 2, 2025 •

edited

Loading

Uh oh!

sharkdp left a comment •

edited

Loading

Uh oh!

Uh oh!

Uh oh!

silamon commented Aug 4, 2025

Uh oh!

carljm commented Aug 5, 2025

Uh oh!

carljm commented Aug 5, 2025 •

edited

Loading

Uh oh!

Uh oh!

Uh oh!

[ty] Diagnostics for async context managers #19704

[ty] Diagnostics for async context managers #19704

Uh oh!

Conversation

silamon commented Aug 2, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

Test Plan

Uh oh!

github-actions bot commented Aug 2, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Diagnostic diff on typing conformance tests

Uh oh!

github-actions bot commented Aug 2, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

mypy_primer results

Uh oh!

sharkdp left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

silamon commented Aug 4, 2025

Uh oh!

carljm commented Aug 5, 2025

Uh oh!

carljm commented Aug 5, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

Uh oh!

silamon commented Aug 2, 2025 •

edited

Loading

github-actions bot commented Aug 2, 2025 •

edited

Loading

github-actions bot commented Aug 2, 2025 •

edited

Loading

`mypy_primer` results

sharkdp left a comment •

edited

Loading

carljm commented Aug 5, 2025 •

edited

Loading