[Dhairya-007]

The keyword validation functions in _keywords and _legacy_keywords are generators that yield ValidationError, but 49 of them were declared -> None. Iterating the result — the only way to use them — was a type error:

for error in additionalProperties(validator, False, instance, schema):
    ...
# error: "None" has no attribute "__iter__" (not iterable)  [attr-defined]
# error: "additionalProperties" does not return a value  [func-returns-value]

A representative usage file reported 7 errors before this change and none after.

The correct type is already in these files

_legacy_keywords.pyi annotates two of its own functions, unevaluatedItems_draft2019 and unevaluatedProperties_draft2019, as Iterator[ValidationError], and protocols.pyi types iter_errors the same way. This just makes the remaining 49 consistent with both, and _legacy_keywords.pyi already imports Iterator and ValidationError for that reason.

Scope

Checked against jsonschema 4.26.0, matching the pinned ~=4.26.0. Every one of the 49 contains a yield or yield from outside any nested function, and at runtime inspect.isgeneratorfunction is True:

>>> list(additionalProperties(v, False, {"a": 1}, {"properties": {}}))
[<ValidationError: "Additional properties are not allowed (*a* was unexpected)">]

• _keywords.pyi — all 36 functions, plus the two imports the file now needs
• _legacy_keywords.pyi — 13 of the 18

The three non-generators in _legacy_keywords are deliberately untouched: ignore_ref_siblings, find_evaluated_item_indexes_by_schema and find_evaluated_property_keys_by_schema genuinely return list types and are already annotated as such.

Why stubtest did not catch this

stubtest does not compare return types. It reports the same 12 pre-existing _format errors before and after this change (optional format dependencies, unrelated) — the error sets diff identically. mypy --strict and pyright are both clean on the stubs, and ruff/black pass.

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉