Restore Blueprint support in CORS type signatures (#410) - #411
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The strict typing added in #409 (released in 6.0.4) narrowed the ``app`` parameter of ``CORS.__init__``/``init_app`` to ``Flask | None``. Flask-CORS supports applying CORS directly to a ``Blueprint`` at runtime (``get_app_kwarg_dict`` already guards for the missing ``config`` attribute, and the exception-handler wrapping is guarded by ``hasattr``), so passing a Blueprint still worked but failed ``mypy --strict`` for downstream users. - Widen the accepted type to ``Flask | Blueprint | None`` on ``CORS.__init__``, ``init_app``, and the internal ``merge_options`` / ``get_cors_options`` / ``get_app_kwarg_dict`` helpers. - Route the Flask-only ``make_response`` / ``handle_exception`` accesses through an ``Any`` alias, gated by the existing ``hasattr`` guard, so the union type checks cleanly. - Add runtime tests exercising CORS on a Blueprint via both the constructor and ``init_app`` (there was previously no Blueprint test coverage). - Add a type-checking regression test (``tests/typecheck``) included in the mypy ``files`` list so a future narrowing of the signature fails CI. - Type-check the ``examples`` directory under strict mypy as well, fixing the ``os.sys`` path hack and adding view return annotations.
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Summary
Fixes #410.
The strict typing added in #409 (released in 6.0.4) narrowed the
appparameter ofCORS.__init__/init_apptoFlask | None. Flask-CORS supports applying CORS directly to aBlueprintat runtime —get_app_kwarg_dictalready guards for the missingconfigattribute, and the exception-handler wrapping is guarded byhasattr(app, "handle_exception")— so passing a Blueprint still worked, but it began failingmypy --strictfor downstream users:This realigns the type annotation with the behavior the runtime guards already implement.
Changes
Flask | Blueprint | NoneonCORS.__init__,init_app, and the internalmerge_options/get_cors_options/get_app_kwarg_dicthelpers.make_response/handle_exceptionaccesses through anAnyalias, gated by the existinghasattrguard, so the wider union type-checks cleanly (no behavior change — the block already only ran for full apps).init_app(there was previously no Blueprint test coverage).tests/typecheck/) included in the mypyfileslist, so a future narrowing of the signature fails CI. Verified: reverting the signature makes mypy fail on exactly that test.examples/directory under strict mypy as well, fixing the non-exportedos.syspath hack and adding view return annotations.Verification
mypy— clean (9 source files)pytest— 98 passed, 1 skippedruff— cleanFollow-up
6.0.4 isn't broken at runtime (it only fails strict typing for Blueprint users), so the suggested path is to release this as 6.0.5 and then yank 6.0.4 on PyPI with a reason pointing at 6.0.5 (yank keeps it installable for anyone already pinned, while steering new installs past it).
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