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Make iscoroutinefunction TypeIs #15928

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d3b5ad9
Make TypeIs
InvincibleRMC Jun 20, 2026
4147a3e
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Jun 20, 2026
05ecac1
Remove unused import
InvincibleRMC Jun 20, 2026
53b2137
Merge branch 'iscoroutinefunction-TypeIs' of github.com:InvincibleRMC…
InvincibleRMC Jun 20, 2026
aa30a76
Update test
InvincibleRMC Jun 20, 2026
f7e25b3
fix inspect tests
InvincibleRMC Jun 20, 2026
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8 changes: 4 additions & 4 deletions stdlib/@tests/test_cases/asyncio/check_coroutines.py
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Original file line number Diff line number Diff line change
Expand Up @@ -19,10 +19,10 @@ def test_iscoroutinefunction_asyncio(
assert_type(x, Callable[[str, int], Coroutine[str, int, bytes]])

if iscoroutinefunction(y): # pyright: ignore
assert_type(y, Callable[[str, int], Coroutine[Any, Any, bytes]])
assert_type(y, Callable[[str, int], Awaitable[bytes]])

if iscoroutinefunction(z): # pyright: ignore
assert_type(z, Callable[[str, int], Coroutine[Any, Any, Any]])
assert_type(z, Callable[[str, int], str | Awaitable[bytes]])

if iscoroutinefunction(xx): # pyright: ignore
assert_type(xx, Callable[..., Coroutine[Any, Any, Any]])
Expand All @@ -31,10 +31,10 @@ def test_iscoroutinefunction_asyncio(
assert_type(x, Callable[[str, int], Coroutine[str, int, bytes]])

if iscoroutinefunction(y):
assert_type(y, Callable[[str, int], Coroutine[Any, Any, bytes]])
assert_type(y, Callable[[str, int], Awaitable[bytes]])

if iscoroutinefunction(z):
assert_type(z, Callable[[str, int], Coroutine[Any, Any, Any]])
assert_type(z, Callable[[str, int], str | Awaitable[bytes]])

if iscoroutinefunction(xx):
assert_type(xx, Callable[..., Coroutine[Any, Any, Any]])
4 changes: 2 additions & 2 deletions stdlib/@tests/test_cases/check_inspect.py
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Original file line number Diff line number Diff line change
Expand Up @@ -17,10 +17,10 @@ def test_iscoroutinefunction_inspect(
assert_type(x, Callable[[str, int], Coroutine[str, int, bytes]])

if inspect.iscoroutinefunction(y):
assert_type(y, Callable[[str, int], CoroutineType[Any, Any, bytes]])
assert_type(y, Callable[[str, int], Awaitable[bytes]])

if inspect.iscoroutinefunction(z):
assert_type(z, Callable[[str, int], CoroutineType[Any, Any, Any]])
assert_type(z, Callable[[str, int], str | Awaitable[bytes]])

if inspect.iscoroutinefunction(xx):
assert_type(xx, Callable[..., CoroutineType[Any, Any, Any]])
14 changes: 7 additions & 7 deletions stdlib/asyncio/coroutines.pyi
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
import sys
from collections.abc import Awaitable, Callable, Coroutine
from typing import Any, ParamSpec, TypeGuard, TypeVar, overload
from typing import Any, ParamSpec, TypeVar, overload
from typing_extensions import TypeIs, deprecated

# Keep asyncio.__all__ updated with any changes to __all__ here
Expand All @@ -25,21 +25,21 @@ if sys.version_info >= (3, 11):
def iscoroutinefunction(func: Callable[..., Coroutine[Any, Any, Any]]) -> bool: ...
@overload
@deprecated("Deprecated since Python 3.14. Use `inspect.iscoroutinefunction()` instead.")
def iscoroutinefunction(func: Callable[_P, Awaitable[_T]]) -> TypeGuard[Callable[_P, Coroutine[Any, Any, _T]]]: ...
def iscoroutinefunction(func: Callable[_P, Awaitable[_T]]) -> TypeIs[Callable[_P, Coroutine[Any, Any, _T]]]: ...
@overload
@deprecated("Deprecated since Python 3.14. Use `inspect.iscoroutinefunction()` instead.")
def iscoroutinefunction(func: Callable[_P, object]) -> TypeGuard[Callable[_P, Coroutine[Any, Any, Any]]]: ...
def iscoroutinefunction(func: Callable[_P, object]) -> TypeIs[Callable[_P, Coroutine[Any, Any, Any]]]: ...
@overload
@deprecated("Deprecated since Python 3.14. Use `inspect.iscoroutinefunction()` instead.")
def iscoroutinefunction(func: object) -> TypeGuard[Callable[..., Coroutine[Any, Any, Any]]]: ...
def iscoroutinefunction(func: object) -> TypeIs[Callable[..., Coroutine[Any, Any, Any]]]: ...
else:
# Sometimes needed in Python < 3.11 due to the fact that it supports @coroutine
# which was removed in 3.11 which the inspect version doesn't support.
@overload
def iscoroutinefunction(func: Callable[..., Coroutine[Any, Any, Any]]) -> bool: ...
@overload
def iscoroutinefunction(func: Callable[_P, Awaitable[_T]]) -> TypeGuard[Callable[_P, Coroutine[Any, Any, _T]]]: ...
def iscoroutinefunction(func: Callable[_P, Awaitable[_T]]) -> TypeIs[Callable[_P, Coroutine[Any, Any, _T]]]: ...
@overload
def iscoroutinefunction(func: Callable[_P, object]) -> TypeGuard[Callable[_P, Coroutine[Any, Any, Any]]]: ...
def iscoroutinefunction(func: Callable[_P, object]) -> TypeIs[Callable[_P, Coroutine[Any, Any, Any]]]: ...
@overload
def iscoroutinefunction(func: object) -> TypeGuard[Callable[..., Coroutine[Any, Any, Any]]]: ...
def iscoroutinefunction(func: object) -> TypeIs[Callable[..., Coroutine[Any, Any, Any]]]: ...
6 changes: 3 additions & 3 deletions stdlib/inspect.pyi
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Original file line number Diff line number Diff line change
Expand Up @@ -239,11 +239,11 @@ def isgeneratorfunction(obj: object) -> TypeGuard[Callable[..., GeneratorType[An
@overload
def iscoroutinefunction(obj: Callable[..., Coroutine[Any, Any, Any]]) -> bool: ...
@overload
def iscoroutinefunction(obj: Callable[_P, Awaitable[_T]]) -> TypeGuard[Callable[_P, CoroutineType[Any, Any, _T]]]: ...
def iscoroutinefunction(obj: Callable[_P, Awaitable[_T]]) -> TypeIs[Callable[_P, CoroutineType[Any, Any, _T]]]: ...

@JelleZijlstra JelleZijlstra Sep 6, 2026

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This is incorrect because it does not return true for all callables that return a CoroutineType.

@linuxdaemon linuxdaemon Oct 31, 2026

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Perhaps a new type needs to be added to represent async functions, because with the current typing system there is no way to type

def foo(a) -> Awaitable[int]:
    return asyncio.Future()

as being distinct from

async def foo(a) -> int:
    return 5

and no way to distinguish them at runtime other than iscoroutinefunction, which can't be accurately typed as the annotations indicate a narrowing on the return type, while the logic of iscoroutinefunction is using flags on the function's code object.

Thus, you can't know definitively if a function is asynchronous in the current system.

@overload
def iscoroutinefunction(obj: Callable[_P, object]) -> TypeGuard[Callable[_P, CoroutineType[Any, Any, Any]]]: ...
def iscoroutinefunction(obj: Callable[_P, object]) -> TypeIs[Callable[_P, CoroutineType[Any, Any, Any]]]: ...
@overload
def iscoroutinefunction(obj: object) -> TypeGuard[Callable[..., CoroutineType[Any, Any, Any]]]: ...
def iscoroutinefunction(obj: object) -> TypeIs[Callable[..., CoroutineType[Any, Any, Any]]]: ...

def isgenerator(object: object) -> TypeIs[GeneratorType[Any, Any, Any]]: ...
def iscoroutine(object: object) -> TypeIs[CoroutineType[Any, Any, Any]]: ...
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