isinstance:
> If classinfo is not a class (type object), it may be a tuple of type objects, or may recursively contain other such tuples (other sequence types are not accepted).

issubclass:
> classinfo may be a tuple of class objects, in which case every entry in classinfo will be checked.

It is unclear from the docs whether
    issubclass(bool, (int, float))
should return True (because bool is a subclass of int),
or False (because bool is NOT a subclass of float).
(It returns True.)

It's likely also false that every entry will be checked, since presumably the function uses short-circuit logic.

issubclass's doc also doesn't mention the recursive tuple case that isinstance's doc has.

Where are you seeing the text you've quoted for isinstance? You've marked as all versions affected, but for the master docs the text for isinstance is different and is unambiguous re treatment of tuple classinfo.

I agree with all your points about issubclass

> It's likely also false that every entry will be checked, since presumably the function uses short-circuit logic.

This, however, would be good to verify first.

My mistake. I selected all versions after checking issubclass for 2.7 and several 3.x, but added the isinstance notes later without paying attention to versions.

I copied the isinstance text from 3.2 docs. As you said, it's not the current text.

docstring for issubclass is a bit clear on the behavior


issubclass(cls, class_or_tuple, /)
    Return whether 'cls' is a derived from another class or is the same class.

    A tuple, as in ``issubclass(x, (A, B, ...))``, may be given as the target to
    check against. This is equivalent to ``issubclass(x, A) or issubclass(x, B)
    or ...`` etc.

> > It's likely also false that every entry will be checked, since presumably the function uses short-circuit logic.

> This, however, would be good to verify first.

Verified.
https://github.com/python/cpython/blob/36dcaab7fde5d2e54cdeff5b705b5adcb27726dd/Objects/abstract.c#L2517

It loops through the tuple until it finds success or error.

It's the same behaviour as for isinstance, could be enough to add "classinfo is treated as in isinstance call" to avoid duplication. This would also solve short-cutting imprecision.