GV

GeezerVison

The World Wide Web, restored to 800 pixels of glory.

Home|About|Gaming cabinet|Archives|How it works|Starter sites

On this site

  • Sign in
  • ActionsCI/CD and automation
  • CodespacesCloud development environments
  • All Features
  • Documentation
  • Training
  • Certifications
  • Build with Copilot
  • Customize Copilot
  • Integrations
  • Trending repos
  • GitHub Sponsors
  • Developer articles
  • Enterprises

This view

  • Original page
  • New address

GeezerVison is showing github.com — Fix `itertools.count()` accepting `None` for `start` and `step` by jseop-lim · Pull Request #1262 · oracle/graalpython

Conversation

@jseop-lim

@jseop-lim jseop-lim commented Oct 31, 2026

Copy link
Copy Markdown
Contributor

Description

Fixes #1251

CountNode declared start and step with useDefaultForNone = true, so an explicit None was replaced by the default before the number check. CPython defaults only an omitted argument and rejects None in itertools_count_impl (itertoolsmodule.c#L4022-L4026).

AS-IS

>>> itertools.count(None)
count(0)
>>> itertools.count(0, None)
count(0)
>>> itertools.count(step=None)
count(0)

TO-BE

>>> itertools.count(None)
TypeError: a number is required
>>> itertools.count(0, None)
TypeError: a number is required
>>> itertools.count(step=None)
TypeError: a number is required

(matching CPython)

Changes

  • Drop useDefaultForNone = true from the start and step annotations of CountNode, so the defaults apply only to an omitted argument.
  • Add tests/test_itertools_count.py.

Testing

mx python-jvm on darwin-aarch64, then the new test_itertools_count.py (3 passed) and the tagged test_itertools (124 passed). The new test fails on the unpatched build. count(), count(5), count(1.5, 2) and count(step=2) print the same as before, and count(start=None) now raises TypeError like CPython 3.13.14.

Sorry, something went wrong.

Uh oh!

There was an error while loading. Please reload this page.
All reactions
@jseop-lim
Reject None for itertools.count() start and step
086037a 
Both arguments were declared with useDefaultForNone, so an explicit
None was replaced by the default and count(None) and count(0, None)
returned count(0). CPython requires a number for any argument that
is passed and raises TypeError for None.

Signed-off-by: Jeongseop Lim <[email protected]>
@oracle-contributor-agreement oracle-contributor-agreement Bot added the OCA Verified All contributors have signed the Oracle Contributor Agreement. label Oct 31, 2026
msimacek
msimacek reviewed Nov 9, 2026
View reviewed changes
Comment thread graalpython/com.oracle.graal.python.test/src/tests/test_itertools_count.py
assert raised


def test_count_rejects_none_start():

@msimacek msimacek Nov 9, 2026

Copy link
Copy Markdown
Contributor

There was a problem hiding this comment.

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Could you please move the tests into the existing test_itertools.py as a new suite? I don't want to end up with a separate test file for every single method

Sorry, something went wrong.

Uh oh!

There was an error while loading. Please reload this page.
All reactions

This branch has not been deployed

No deployments
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@msimacek msimacek msimacek left review comments

At least 1 approving review is required to merge this pull request.

Uh oh!

There was an error while loading. Please reload this page.

Assignees

No one assigned

Labels

OCA Verified All contributors have signed the Oracle Contributor Agreement.

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

[Bug]: itertools.count() accepts None for start and step

Uh oh!

There was an error while loading. Please reload this page.

2 participants

@jseop-lim @msimacek
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
You are visitor 01402503 — GeezerVison does not store the pages you look up.
Best viewed with Netscape Navigator 4.7 or Internet Explorer 6 at 800×600. No cookies required.