[issue41987] singledispatchmethod raises an error when relying on a forward declaration

[Guido van Rossum]

Guido van Rossum <guido at python.org> added the comment:

I spent some time debugging this looking for the root cause.

I think it looks like the recursion check in ForwardRef._evaluate() fails to trigger.  At some point recursive_guard is a frozen set containing "'Integer'" (i.e. a string whose first and last character are single quotes, while self.__forward_arg__ is 'Integer' (i.e. a string that does not contain quotes).

I'm running out of time for the rest of the investigation, so feel free to confirm this and go down the rabbit hole from there...

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue41987>
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