GV

GeezerVison

The World Wide Web, restored to 800 pixels of glory.

Home|About|Gaming cabinet|Archives|How it works|Starter sites

On this site

  • Sign in
  • ActionsCI/CD and automation
  • CodespacesCloud development environments
  • All Features
  • Documentation
  • Training
  • Certifications
  • Build with Copilot
  • Customize Copilot
  • Integrations
  • Trending repos
  • GitHub Sponsors
  • Developer articles
  • Enterprises

This view

  • Original page
  • New address

GeezerVison is showing github.com — [functools] Make `partial` covariant in its return type by sumit-2007-git · Pull Request #16769 · python/typeshed

Conversation

@sumit-2007-git

@sumit-2007-git sumit-2007-git commented Nov 11, 2026

Copy link
Copy Markdown

Partially addresses #10566 (specifically functools.partial; partialmethod and singledispatch are left untouched to avoid overlapping with #16736 and #15635).

functools.partial only exposes _T via read-only properties (func) and return positions (__call__, __get__) plus __new__, so _T_co makes partial[Child] assignable to partial[Parent], as noted by @JelleZijlstra in #10566.

Verification

  • Added a covariance test (check_partial_covariance) in stdlib/@tests/test_cases/check_functools.py.
  • Tested locally with mypy (3.10, 3.14), pyright (stricter 3.10, 3.14, and testcases 3.12), ty, pyrefly, stubtest on functools, regr_test, ruff, black, flake8, and check_typeshed_structure.py.

Sorry, something went wrong.

Uh oh!

There was an error while loading. Please reload this page.
All reactions
@sumit-2007-git
[functools] Make partial covariant in its return type
f15c352
@github-actions

This comment has been minimized.

Sign in to view
@sumit-2007-git
Merge branch 'main' into fix/functools-partial-covariance
5676fca
@github-actions

github-actions Bot commented Nov 12, 2026

Copy link
Copy Markdown
Contributor

Diff from mypy_primer, showing the effect of this PR on open source code:

jax (https://github.com/google/jax)
- jax/experimental/pallas/ops/tpu/splash_attention/splash_attention_kernel.py:2598: error: Argument 1 to "_process_dynamic_mask" has incompatible type "Array | MultiHeadMask"; expected "Array"  [arg-type]
- jax/experimental/pallas/ops/tpu/splash_attention/splash_attention_kernel.py:2614: error: Argument 1 to "_process_dynamic_mask" has incompatible type "Array | MultiHeadMask"; expected "Array"  [arg-type]
- jax/experimental/pallas/ops/tpu/splash_attention/splash_attention_kernel.py:2615: error: Argument 2 to "_process_dynamic_mask" has incompatible type "tuple[int | Any | None, int | Any | None]"; expected "tuple[int, int]"  [arg-type]
- jax/experimental/pallas/ops/tpu/splash_attention/splash_attention_kernel.py:2624: error: Argument 1 to "_process_dynamic_mask" has incompatible type "Array | MultiHeadMask"; expected "Array"  [arg-type]
- jax/experimental/pallas/ops/tpu/splash_attention/splash_attention_kernel.py:2625: error: Argument 2 to "_process_dynamic_mask" has incompatible type "tuple[int | Any | None, int | Any | None]"; expected "tuple[int, int]"  [arg-type]
All reactions

Sorry, something went wrong.

Uh oh!

There was an error while loading. Please reload this page.

This branch has not been deployed

No deployments
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

No reviews

Uh oh!

There was an error while loading. Please reload this page.

Assignees

No one assigned

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

Uh oh!

There was an error while loading. Please reload this page.

1 participant

@sumit-2007-git
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
You are visitor 01402503 — GeezerVison does not store the pages you look up.
Best viewed with Netscape Navigator 4.7 or Internet Explorer 6 at 800×600. No cookies required.