python / python/mypy

mypy should use CoroutineType instead of Coroutine for return types of async def functions

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#18,635 3 comments 2 reactions 0 assignees View on GitHub

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feature
Dominant language
Python
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Forks
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PR merge metrics
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Description

Feature

types.CoroutineType is defined as:

The type of coroutine objects, created by async def functions.

Evidently, async def functions return them. For context, they're a subclass of collections.abc.Coroutine with extra features.

Pitch

https://github.com/python/mypy/issues/18634 ran into this.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading the linked issue #18634 and tracing mypy's handling of return types for async def functions. Confirm where Coroutine is selected and identify the relevant tests or entry points before changing behavior. Done means async def return types use types.CoroutineType and the existing typing tests pass.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
devtools
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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