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 — gh-98724: Fix type punning issue in Py_SETREF() by vstinner · Pull Request #99739 · python/cpython

Conversation

@vstinner

@vstinner vstinner commented Nov 23, 2022 •
edited by bedevere-bot
Loading

Uh oh!

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

Copy link
Copy Markdown
Member

Fix type punning issue in Py_CLEAR(), Py_SETREF() and Py_XSETREF() macros. Don't cast pointers to avoid type punning which cause miscompilation of functions using these macros.

  • Issue: Macro Py_CLEAR references argument two times. #98724

Sorry, something went wrong.

Uh oh!

There was an error while loading. Please reload this page.
All reactions
@bedevere-bot bedevere-bot mentioned this pull request Nov 23, 2022
Macro Py_CLEAR references argument two times. #98724
Closed
@bedevere-bot bedevere-bot added the awaiting core review label Nov 23, 2022
@vstinner vstinner added skip news and removed awaiting core review labels Nov 23, 2022
@vstinner
vstinner marked this pull request as draft November 23, 2022 23:25
@vstinner
gh-98724: Fix type punning issue in Py_SETREF()
822d566 
Fix type punning issue in Py_CLEAR(), Py_SETREF() and Py_XSETREF()
macros. Don't cast pointers to avoid type punning which cause
miscompilation of functions using these macros.
This was referenced Nov 23, 2022
Type punning (and strict aliasing) issue in Py_CLEAR() and Py_SETREF() macros: Python --enable-pystats is miscompiled #99701
Closed
Revert "gh-98724: Fix Py_CLEAR() macro side effects" #99737
Merged
@vstinner

vstinner commented Nov 23, 2022

Copy link
Copy Markdown
Member Author 
#define _PY_TYPEOF(EXPR) __typeof__(EXPR)

On GCC and clang, typeof() can maybe used. In "GNU mode", typeof is treated as a keyword by the C compiler.

On MSVC, if __typeof__() doesn't work, maybe decltype() can be used instead.
All reactions

Sorry, something went wrong.

Uh oh!

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

vstinner commented Nov 23, 2022

Copy link
Copy Markdown
Member Author

Ah, building Python with the PR fails on Windows (MSVC) with:

warning C4013: '__typeof__' undefined
All reactions

Sorry, something went wrong.

Uh oh!

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

vstinner commented Nov 29, 2022

Copy link
Copy Markdown
Member Author

Since MSVC doesn't implement __typeof__(), I don't think that this approach works. I would like the C API to behave the same on all platforms: see #98724 (comment) I close my PR.
All reactions

Sorry, something went wrong.

Uh oh!

There was an error while loading. Please reload this page.
@vstinner vstinner closed this Nov 29, 2022
@vstinner
vstinner deleted the setref_typeof branch November 29, 2022 16:11
@vstinner vstinner mentioned this pull request Dec 7, 2022
gh-98724: Fix Py_CLEAR() macro side effects (#99100) #100070
Merged
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

No reviews

Uh oh!

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

Assignees

No one assigned

Labels

skip news

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

Uh oh!

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

2 participants

@vstinner @bedevere-bot
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.