return in finally swallows exceptions

[iritkatriel]

Things to check first

• I have searched the existing issues and didn't find my bug already reported there

• I have checked that my bug is still present in the latest release

AnyIO version

mater branch

Python version

NA

What happened?

In

anyio/src/anyio/from_thread.py

Line 119 in 3a62738

return result

there is a return statement in a finally block, which would swallow any in-flight exception.

This means that if an unhandled exception (including a BaseException such as KeyboardInterrupt) is raised from the try body, it will not propagate on as expected.

If the intention is to suppress all exceptions, I would propose to make this clear by using except BaseException.

See also https://docs.python.org/3/tutorial/errors.html#defining-clean-up-actions.

How can we reproduce the bug?

NA

[agronholm]

Note to self: this can be found in anyio.from_thread._BlockingAsyncContextManager.run_async_cm().