The bool of a large range raises OverflowError:

    >>> bool(range(2**63))
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    OverflowError: Python int too large to convert to C ssize_t

This is a side-effect of len raising OverflowError, which is a general problem that's nontrivial to fix (the sq_length slot is constrained to return a ssize_t). In theory, though, it would be possible to implement nb_bool for range objects to do the right thing.

In practice, this may well not be worth fixing, though I think it's at least worth reporting.

+1 for implementing nb_bool for range objects.

Here's a patch with range_bool() implementation, tests and the docs update.

I'm not sure how it should be documented. I've specified it as 
versionchanged:: 3.6

> I'm not sure how it should be documented.

I think a change at this level probably isn't worth documenting in the official docs; it's enough that there's a Misc/NEWS entry for it.

I've removed the documentation changes from the patch.

Patch LGTM. You could safely drop the initialisers beyond `nb_bool` in the `range_as_number` struct (per C99 6.7.8p21), but it's fine as it is.

Following the python-dev discussion [1] I've added a variant of the patch that uses c99 designated initializers [2]

[1] https://mail.python.org/pipermail/python-dev/2017-January/147175.html
[2] https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html

This patch looks ready to go.  I'll wait a bit to see it there are any other comments.  If not, I'll apply it shortly.

LGTM, except 2-space indent.

I've updated the patch to use 4-space indent (pep-7).

I've added space around "=" (pep-7); unlike the usual
"dict(designator=value)" -- no space around "=" for keyword argument
(pep-8).

Latest patch LGTM too.

Akira, could you open a pull request on GitHub?

> Akira, could you open a pull request on GitHub?

Done. PR 699

In issue29840 proposed an alternate and more general solution. But I think that nb_bool should be implemented for range objects since issue29840 is 3.7 only and nb_bool is faster.

Thank you Akira for your patch.

New changeset 4276068fe57e93b4c8d428f0b1cde8ca04b8fb99 by Serhiy Storchaka in branch '3.5':
bpo-28876: bool of large range raises OverflowError (#699) (#735)
https://github.com/python/cpython/commit/4276068fe57e93b4c8d428f0b1cde8ca04b8fb99

New changeset 6fad4090ec9a27f8572bb00661b9890f01fb62f7 by Serhiy Storchaka in branch '3.6':
bpo-28876: bool of large range raises OverflowError (#699) (#734)
https://github.com/python/cpython/commit/6fad4090ec9a27f8572bb00661b9890f01fb62f7

New changeset e46fb8611867fa3b407a813f53137929b7cb4a10 by Serhiy Storchaka (4kir4) in branch 'master':
bpo-28876: bool of large range raises OverflowError (#699)
https://github.com/python/cpython/commit/e46fb8611867fa3b407a813f53137929b7cb4a10