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Constrained TypeVars with Any default #20184
Description
Bug Report
In python/typeshed#13683 I'm trying to change a type var to the following:
_I = TypeVar("_I", int, bytes, float, bool, default=Any) # possibly memoryview typesUnfortunately, mypy complains: error: TypeVar default must be one of the constraint types [misc]. While this is of course generally sound advice, a default of Any should always be permissible, as this allows memoryview to stand for any possible memoryview type. Without it, users are forced to write memoryview[Any] in every instance, which is unreasonable.
Your Environment
- Mypy version used: 1.18.2
Activity
sterliakov commentedon Nov 7, 2025
I agree with your position, yet the spec seems to disallow that:
srittau commentedon Nov 10, 2025
Thanks, for pointing this out. I've opened a discussion at https://discuss.python.org/t/constrained-type-vars-with-any-default/104799.