[ty] Detect terminal await calls to async functions#23479
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Typing conformance resultsNo changes detected ✅ |
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Memory usage reportSummary
Significant changesClick to expand detailed breakdownprefect
trio
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| Lint rule | Added | Removed | Changed |
|---|---|---|---|
invalid-await |
40 | 0 | 0 |
invalid-return-type |
1 | 3 | 0 |
type-assertion-failure |
1 | 0 | 0 |
| Total | 42 | 3 | 0 |
charliermarsh
requested review from
AlexWaygood,
carljm,
dcreager,
ibraheemdev and
sharkdp
as code owners
Member
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Nice, three false positives going away on mongo-python-driver and trio! |
sharkdp
approved these changes
Feb 23, 2026
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| if no_overloads_return_never && !any_overload_is_generic { | ||
| if no_overloads_return_never && !any_overload_is_generic && !is_await { |
Contributor
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Instead of excluding async functions from the fast-path check, I think we could adapt the check above to get the return type of the coroutine and unwrap it, to see if it's Never.
Contributor
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I'm playing around with removing that optimization though, so maybe let's keep this as is.
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| ## Narrowing after awaiting a `NoReturn` async function | ||
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| When an async function is annotated as returning `NoReturn`, awaiting it should be treated as | ||
| terminal, just like calling a synchronous `NoReturn` function. | ||
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| ```py | ||
| from typing import NoReturn | ||
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| async def stop() -> NoReturn: | ||
| raise NotImplementedError | ||
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| async def main(flag: bool): | ||
| if flag: | ||
| x = 1 | ||
| await stop() | ||
| else: | ||
| x = 2 | ||
| pass | ||
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| reveal_type(x) # revealed: Literal[2] | ||
| ``` |
Contributor
There was a problem hiding this comment.
This test has nothing to do with narrowing, and should therefore go into the reachability section.
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Summary
Closes astral-sh/ty#2789.