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[ty] Type inference for @asynccontextmanager#21876

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sharkdp merged 2 commits intomainfrom
david/fix-1804
Dec 9, 2025
Merged

[ty] Type inference for @asynccontextmanager#21876
sharkdp merged 2 commits intomainfrom
david/fix-1804

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@sharkdp sharkdp commented Dec 9, 2025 •
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Summary

This PR adds special handling for asynccontextmanager calls as a temporary solution for astral-sh/ty#1804. We will be able to remove this soon once we have support for generic protocols in the solver.

closes astral-sh/ty#1804

Ecosystem

+ tests/test_downloadermiddleware.py:305:56: error[invalid-argument-type] Argument to bound method `download` is incorrect: Expected `Spider`, found `Unknown | Spider | None`
+ tests/test_downloadermiddleware.py:305:56: warning[possibly-missing-attribute] Attribute `spider` may be missing on object of type `Crawler | None`

These look like true positives

+ pymongo/asynchronous/database.py:1021:35: error[invalid-assignment] Object of type `(AsyncClientSession & ~AlwaysTruthy & ~AlwaysFalsy) | (_ServerMode & ~AlwaysFalsy) | Unknown | Primary` is not assignable to `_ServerMode | None`
+ pymongo/asynchronous/database.py:1025:17: error[invalid-argument-type] Argument to bound method `_conn_for_reads` is incorrect: Expected `_ServerMode`, found `_ServerMode | None`

Known problems or true positives, just caused by the new type for session

- src/integrations/prefect-sqlalchemy/prefect_sqlalchemy/database.py:269:16: error[invalid-return-type] Return type does not match returned value: expected `Connection | AsyncConnection`, found `_GeneratorContextManager[Unknown, None, None] | _AsyncGeneratorContextManager[Unknown, None] | Connection | AsyncConnection`
+ src/integrations/prefect-sqlalchemy/prefect_sqlalchemy/database.py:269:16: error[invalid-return-type] Return type does not match returned value: expected `Connection | AsyncConnection`, found `_GeneratorContextManager[Unknown, None, None] | _AsyncGeneratorContextManager[AsyncConnection, None] | Connection | AsyncConnection`

Just a more concrete type

- src/prefect/flow_engine.py:1277:24: error[missing-argument] No argument provided for required parameter `cls`
- src/prefect/server/api/server.py:696:49: error[missing-argument] No argument provided for required parameter `cls`
- src/prefect/task_engine.py:1426:24: error[missing-argument] No argument provided for required parameter `cls`

Good

Test Plan

  • Adapted and newly added Markdown tests
  • Tested on internal codebase

@sharkdp sharkdp added ty Multi-file analysis & type inference ecosystem-analyzer labels Dec 9, 2025
sharkdp
sharkdp commented Dec 9, 2025
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crates/ty_python_semantic/src/types/call/bind.rs Outdated
Comment on lines 4663 to 4665
if yield_ty.is_divergent() {
return Some(yield_ty);
}
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@sharkdp sharkdp Dec 9, 2025

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This took me a while to figure out. Looks related to astral-sh/ty#1821 / astral-sh/ty#1821. If we don't do this, we end up with unions of the actual type that we want to have and Divergent

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astral-sh-bot bot commented Dec 9, 2025 •
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Diagnostic diff on typing conformance tests

No changes detected when running ty on typing conformance tests ✅

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astral-sh-bot bot commented Dec 9, 2025 •
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mypy_primer results

Changes were detected when running on open source projects 
beartype (https://github.com/beartype/beartype)
- beartype/claw/_package/clawpkgtrie.py:66:29: warning[unsupported-base] Unsupported class base with type `<class 'dict[str, PackagesTrieBlacklist]'> | <class 'dict[str, Divergent]'>`
- beartype/claw/_package/clawpkgtrie.py:247:29: warning[unsupported-base] Unsupported class base with type `<class 'dict[str, PackagesTrieWhitelist]'> | <class 'dict[str, Divergent]'>`
- Found 494 diagnostics
+ Found 492 diagnostics

scrapy (https://github.com/scrapy/scrapy)
+ tests/test_downloadermiddleware.py:305:56: error[invalid-argument-type] Argument to bound method `download` is incorrect: Expected `Spider`, found `Unknown | Spider | None`
+ tests/test_downloadermiddleware.py:305:56: warning[possibly-missing-attribute] Attribute `spider` may be missing on object of type `Crawler | None`
- Found 1735 diagnostics
+ Found 1737 diagnostics

mongo-python-driver (https://github.com/mongodb/mongo-python-driver)
+ pymongo/asynchronous/database.py:1021:35: error[invalid-assignment] Object of type `(AsyncClientSession & ~AlwaysTruthy & ~AlwaysFalsy) | (_ServerMode & ~AlwaysFalsy) | Unknown | Primary` is not assignable to `_ServerMode | None`
+ pymongo/asynchronous/database.py:1025:17: error[invalid-argument-type] Argument to bound method `_conn_for_reads` is incorrect: Expected `_ServerMode`, found `_ServerMode | None`
- Found 460 diagnostics
+ Found 462 diagnostics

trio (https://github.com/python-trio/trio)
+ src/trio/_channel.py:610:12: error[invalid-return-type] Return type does not match returned value: expected `(**P@as_safe_channel) -> AbstractAsyncContextManager[ReceiveChannel[T@as_safe_channel], bool | None]`, found `((self, *args: P@as_safe_channel.args, **kwargs: P@as_safe_channel.kwargs) -> _AsyncGeneratorContextManager[Unknown, None]) | Unknown`
- Found 494 diagnostics
+ Found 495 diagnostics

scikit-build-core (https://github.com/scikit-build/scikit-build-core)
+ src/scikit_build_core/_logging.py:153:13: warning[unsupported-base] Unsupported class base with type `<class 'Mapping[str, Style]'> | <class 'Mapping[str, Divergent]'>`
- Found 41 diagnostics
+ Found 42 diagnostics

prefect (https://github.com/PrefectHQ/prefect)
- src/integrations/prefect-sqlalchemy/prefect_sqlalchemy/database.py:269:16: error[invalid-return-type] Return type does not match returned value: expected `Connection | AsyncConnection`, found `_GeneratorContextManager[Unknown, None, None] | _AsyncGeneratorContextManager[Unknown, None] | Connection | AsyncConnection`
+ src/integrations/prefect-sqlalchemy/prefect_sqlalchemy/database.py:269:16: error[invalid-return-type] Return type does not match returned value: expected `Connection | AsyncConnection`, found `_GeneratorContextManager[Unknown, None, None] | _AsyncGeneratorContextManager[AsyncConnection, None] | Connection | AsyncConnection`
- src/prefect/flow_engine.py:1277:24: error[missing-argument] No argument provided for required parameter `cls`
- src/prefect/server/api/server.py:696:49: error[missing-argument] No argument provided for required parameter `cls`
- src/prefect/task_engine.py:1426:24: error[missing-argument] No argument provided for required parameter `cls`
- Found 5480 diagnostics
+ Found 5477 diagnostics

No memory usage changes detected ✅

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astral-sh-bot bot commented Dec 9, 2025 •
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ecosystem-analyzer results

Lint rule Added Removed Changed
invalid-argument-type 2 0 0
invalid-return-type 1 0 1
invalid-assignment 1 0 0
possibly-missing-attribute 1 0 0
unsupported-base 0 1 0
Total 5 1 1

Full report with detailed diff (timing results)

@sharkdp sharkdp force-pushed the david/fix-1804 branch 2 times, most recently from 810e257 to f02359c Compare December 9, 2025 20:40
sharkdp
sharkdp commented Dec 9, 2025
View reviewed changes
scripts/check_ecosystem.py

@asynccontextmanager
async def clone(self: Self, checkout_dir: Path) -> AsyncIterator[Path]:
async def clone(self: Self, checkout_dir: Path) -> AsyncIterator[str]:
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Oh look, we found a bug.

@sharkdp sharkdp marked this pull request as ready for review December 9, 2025 20:56
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astral-sh-bot bot commented Dec 9, 2025 •
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ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.

carljm
carljm approved these changes Dec 9, 2025
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This looks like a reasonable temporary patch for a common case to me!

dcreager
dcreager approved these changes Dec 9, 2025
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👍 thank you!

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sharkdp commented Dec 9, 2025

Merging despite the failing benchmark run (timeout). Benchmarks were running on a previous version of this PR and I only made a completely trivial change since then.

@sharkdp sharkdp merged commit a9be810 into main Dec 9, 2025
39 of 40 checks passed
@sharkdp sharkdp deleted the david/fix-1804 branch December 9, 2025 21:49
dcreager added a commit that referenced this pull request Dec 10, 2025
@dcreager
Merge remote-tracking branch 'origin/main' into dcreager/callable-return
4f7ad7b 
* origin/main: (33 commits)
  [ty] Simplify union lower bounds and intersection upper bounds in constraint sets (#21871)
  [ty] Collapse `never` paths in constraint set BDDs (#21880)
  Fix leading comment formatting for lambdas with multiple parameters (#21879)
  [ty] Type inference for `@asynccontextmanager` (#21876)
  Fix comment placement in lambda parameters (#21868)
  [`pylint`] Detect subclasses of builtin exceptions (`PLW0133`) (#21382)
  Fix stack overflow with recursive generic protocols (depth limit) (#21858)
  New diagnostics for unused range suppressions (#21783)
  [ty] Use default settings in completion tests
  [ty] Infer type variables within generic unions  (#21862)
  [ty] Fix overload filtering to prefer more "precise" match (#21859)
  [ty] Stabilize auto-import
  [ty] Fix reveal-type E2E test (#21865)
  [ty] Use concise message for LSP clients not supporting related diagnostic information (#21850)
  Include more details in Tokens 'offset is inside token' panic message (#21860)
  apply range suppressions to filter diagnostics (#21623)
  [ty] followup: add-import action for `reveal_type` too (#21668)
  [ty] Enrich function argument auto-complete suggestions with annotated types
  [ty] Add autocomplete suggestions for function arguments
  [`flake8-bugbear`] Accept immutable slice default arguments (`B008`) (#21823)
  ...
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@dcreager dcreager dcreager approved these changes

@carljm carljm carljm approved these changes

@AlexWaygood AlexWaygood Awaiting requested review from AlexWaygood AlexWaygood is a code owner

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async with usage with asynccontextmanager-decorated function results in Unknown

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