[ty] Ban nested Required/NotRequired, and ban them both outside of TypedDict fields#23627
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AlexWaygood merged 3 commits intomainfrom Feb 28, 2026
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Add two missing validations for `Required` and `NotRequired` type qualifiers: 1. Reject their use outside of TypedDict class bodies (e.g. in regular classes, at module level, or in function bodies). Also reject `ReadOnly` outside TypedDict since it has the same constraint. 2. Reject nested usage like `Required[Required[int]]`, `NotRequired[NotRequired[int]]`, or `Required[NotRequired[int]]`. https://claude.ai/code/session_01UbEm9rHWd2fidUX2gptzF7
Keep all TypedDict-related tests together in one file rather than creating a separate type_qualifiers/required.md file. https://claude.ai/code/session_01UbEm9rHWd2fidUX2gptzF7
Typing conformance results improved 🎉The percentage of diagnostics emitted that were expected errors increased from 85.39% to 85.44%. The percentage of expected errors that received a diagnostic increased from 76.01% to 76.28%. Summary
True positives addedDetails
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Memory usage reportMemory usage unchanged ✅ |
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charliermarsh
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Feb 28, 2026
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charliermarsh
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This looks reasonable to me.
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From mypy_primer it looks like we might have some false positives around functional TypedDicts... waiting for the ecosystem-analyzer report. Will check back in on it tomorrow... |
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| Lint rule | Added | Removed | Changed |
|---|---|---|---|
invalid-await |
0 | 40 | 0 |
invalid-argument-type |
0 | 0 | 3 |
invalid-return-type |
0 | 1 | 0 |
| Total | 0 | 41 | 3 |
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carljm
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* main: [ty] Move binary expression logic out of `builder.rs` (#23649) [ty] Limit recursion depth when displaying self-referential function types (#23647) [ty] Move comparison logic out of `builder.rs` (#23646) Avoid inserting redundant `None` elements in UP045 (#23459) [ty] Add more ParamSpec validation for `P.args` and `P.kwargs` (#23640) [ty] Sync vendored typeshed stubs (#23642) [ty] Fix inference of `t.__mro__` if `t` is an instance of `type[Any]` (#23632) [ty] Detect inconsistent generic base class specializations (#23615) [ty] Validate type variable defaults don't reference later type parameters or type parameters out of scope (#23623) [ty] Ban nested `Required`/`NotRequired`, and ban them both outside of `TypedDict` fields (#23627) [ty] Reject generic metaclasses parameterized by type variables (#23628) Update default Python version examples (#23605) fix binops with NewType of float and Unknown (#23620) [ty] Reject functions with PEP-695 type parameters that shadow type parameters from enclosing scopes (#23619) [ty] Reject ellipsis literals in odd places in type/annotation expressions (#23611) [ty] hash-cons `UseDefMap` fields (#23283)
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Summary
Add validation for
typing.Required,typing.NotRequired, andtyping.ReadOnlytype qualifiers to ensure they are only validly used withinTypedDictclass bodies.Test Plan
mdtests