ruff/crates/ty_python_semantic/resources/mdtest/expression
David Peter 4ecf1d205a
[ty] Support async/await, async with and yield from (#19595)
## Summary

- Add support for the return types of `async` functions
- Add type inference for `await` expressions
- Add support for `async with` / async context managers
- Add support for `yield from` expressions

This PR is generally lacking proper error handling in some cases (e.g.
illegal `__await__` attributes). I'm planning to work on this in a
follow-up.

part of https://github.com/astral-sh/ty/issues/151

closes https://github.com/astral-sh/ty/issues/736

## Ecosystem

There are a lot of true positives on `prefect` which look similar to:
```diff
prefect (https://github.com/PrefectHQ/prefect)
+ src/integrations/prefect-aws/tests/workers/test_ecs_worker.py:406:12: error[unresolved-attribute] Type `str` has no attribute `status_code`
```

This is due to a wrong return type annotation
[here](e926b8c4c1/src/integrations/prefect-aws/tests/workers/test_ecs_worker.py (L355-L391)).

```diff
mitmproxy (https://github.com/mitmproxy/mitmproxy)
+ test/mitmproxy/addons/test_clientplayback.py:18:1: error[invalid-argument-type] Argument to function `asynccontextmanager` is incorrect: Expected `(...) -> AsyncIterator[Unknown]`, found `def tcp_server(handle_conn, **server_args) -> Unknown | tuple[str, int]`
```


[This](a4d794c59a/test/mitmproxy/addons/test_clientplayback.py (L18-L19))
is a true positive. That function should return
`AsyncIterator[Address]`, not `Address`.

I looked through almost all of the other new diagnostics and they all
look like known problems or true positives.

## Typing conformance

The typing conformance diff looks good.

## Test Plan

New Markdown tests
2025-07-30 11:51:21 +02:00
..
assert.md
attribute.md
boolean.md [ty] Make tuple subclass constructors sound (#19469) 2025-07-21 21:25:11 +00:00
if.md
lambda.md [ty] Treat lambda functions as instances of types.FunctionType (#18431) 2025-06-02 16:46:26 +01:00
len.md [ty] Extend tuple __len__ and __bool__ special casing to also cover tuple subclasses (#19289) 2025-07-21 12:50:46 +00:00
yield_and_yield_from.md [ty] Support async/await, async with and yield from (#19595) 2025-07-30 11:51:21 +02:00