bool of large range raises OverflowError

[mdickinson]

BPO	28876
Nosy	@rhettinger, @mdickinson, @methane, @4kir4, @serhiy-storchaka
PRs	bpo-28876: bool of large range raises OverflowError #699 bpo-28876: bool of large range raises OverflowError (#699) #734 bpo-28876: bool of large range raises OverflowError (#699) #735
Files	range_bool.patch range_bool-no_docs.patch: no docs updates range_bool-c99-designated-initializers.patch: use c99 designated initializers range_bool-c99-designated-initializers-indent.patch: use 4-space indent, space around "="

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/rhettinger'
closed_at = <Date 2017-03-20.07:39:08.069>
created_at = <Date 2016-12-05.09:37:42.421>
labels = ['interpreter-core', 'type-bug', '3.7']
title = 'bool of large range raises OverflowError'
updated_at = <Date 2017-03-24.20:18:43.324>
user = 'https://github.com/mdickinson'

bugs.python.org fields:

activity = <Date 2017-03-24.20:18:43.324>
actor = 'serhiy.storchaka'
assignee = 'rhettinger'
closed = True
closed_date = <Date 2017-03-20.07:39:08.069>
closer = 'serhiy.storchaka'
components = ['Interpreter Core']
creation = <Date 2016-12-05.09:37:42.421>
creator = 'mark.dickinson'
dependencies = []
files = ['45765', '45773', '46378', '46391']
hgrepos = []
issue_num = 28876
keywords = ['patch']
message_count = 18.0
messages = ['282402', '282405', '282414', '282418', '282506', '283137', '286008', '286048', '286055', '286089', '286092', '289772', '289778', '289786', '289876', '290129', '290130', '290132']
nosy_count = 5.0
nosy_names = ['rhettinger', 'mark.dickinson', 'methane', 'akira', 'serhiy.storchaka']
pr_nums = ['699', '734', '735']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue28876'
versions = ['Python 3.5', 'Python 3.6', 'Python 3.7']

[mdickinson]

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.

[rhettinger]

+1 for implementing nb_bool for range objects.

[4kir4]

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

[mdickinson]

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.

[4kir4]

I've removed the documentation changes from the patch.

[mdickinson]

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.

[4kir4]

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

[rhettinger]

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.

[methane]

LGTM, except 2-space indent.

[4kir4]

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).

[mdickinson]

Latest patch LGTM too.