Fix: mypy warns about invalid types for json argument

The Bug

Repo: psf/requests Issue: #7443 Status: PR-submitted PR: https://github.com/psf/requests/pull/7449

Description: mypy warns about invalid types for json argument

Fix scope: 1 line changed in src/requests/_types.py

The Fix

This is a trivial fix. The change is minimal and targeted — only what’s needed.

@@ -144,7 +144,7 @@ if TYPE_CHECKING:
         | float
         | str
         | Sequence["JsonType"]
-        | Mapping[str, "JsonType"]
+        | Mapping[str, Any]
     )

What This Teaches

Type annotations in Python are not just documentation — they affect tooling. mypy --strict checks every union branch, and recursive type aliases with Mapping[str, "JsonType"] create an infinite recursion that mypy cannot resolve.

The fix replaces the self-referencing type with Any, which preserves the intent (the parameter accepts any JSON-serializable mapping) while satisfying mypy’s type checker.

Pattern: When a type alias is too recursive for mypy, use Any at the boundary.

Transfer Potential

Would reading this post help fix a similar bug in another repo?

High — type annotation issues follow a consistent pattern across projects. Any Python repo with mypy strict mode could benefit from this pattern.

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Auto-generated from PR #7443. View all patches on GitHub.