bpo-12159: document sys.maxsize limit in len() function reference

[Zac-HD]

See:

• BPO-12159: "needs to be documented",
• BPO-15718: added note to datamodel docs for __len__ method but not len(), and
• BPO-21444: change request / wontfix

https://bugs.python.org/issue12159

[cool-RR]

I think that this is a good addition to the documentation, but the example with range is weird. Maybe you mean that big ranges, such as range(10 ** 100) will be too big. That isn't clear from your text.

[vstinner]

Suggested change

	on inputs larger than :data:`sys.maxsize`, such as :class:`range`.
	on lengths larger than :data:`sys.maxsize`.

I don't understand the "such as range()" part. len(range(5)) returns 5, it doesn't fail with overflow?

[Zac-HD]

I've clarified that this is for cases such as range(2 ** 64).

[vstinner]

LGTM, but I would prefer to get a second review. @csabella @serhiy-storchaka @JulienPalard: What do you think of this len note?

[csabella]

LGTM. Since this has been brought up multiple times, I think it's best to document it, especially since __len__ had a note added in the past. Thanks for the patch, @Zac-HD!

[bedevere-bot]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[Zac-HD]

I have made the requested changes; please review again

[bedevere-bot]

Thanks for making the requested changes!

@csabella, @vstinner: please review the changes made to this pull request.