Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Walrus in comprehension can leak into PEP 695 scope #104640

Closed
JelleZijlstra opened this issue May 19, 2023 · 0 comments · Fixed by #104641
Closed

Walrus in comprehension can leak into PEP 695 scope #104640

JelleZijlstra opened this issue May 19, 2023 · 0 comments · Fixed by #104641
Assignees
@JelleZijlstra
Labels
type-bug An unexpected behavior, bug, or error

Comments

@JelleZijlstra
Copy link
Member

JelleZijlstra commented May 19, 2023 •
edited by bedevere-bot
Loading

Example:

>>> class B: pass
... 
>>> class X[T]([(x := 3) for _ in range(2)] and B): print(x)
... 
3

This is because a walrus in a comprehension assigns to the immediately enclosing scope, which is now the type parameter scope. I don't think this causes any concrete problem right now, but I don't like it because I'd like to preserve the invariant that type parameters are the only names that can be defined in PEP 695 scopes.

Linked PRs
@JelleZijlstra JelleZijlstra added the type-bug An unexpected behavior, bug, or error label May 19, 2023
@JelleZijlstra JelleZijlstra self-assigned this May 19, 2023
JelleZijlstra added a commit to JelleZijlstra/cpython that referenced this issue May 19, 2023
@JelleZijlstra
pythongh-104640: Disallow walrus in comprehension within type scopes
d43cf9c
@JelleZijlstra JelleZijlstra mentioned this issue May 19, 2023
Merged
JelleZijlstra added a commit that referenced this issue May 19, 2023
@JelleZijlstra
gh-104640: Disallow walrus in comprehension within type scopes (#104641)
8a8853a
carljm added a commit to gsallam/cpython_with_perfmap_apii that referenced this issue May 20, 2023
@carljm
Merge branch 'main' into gsallam/main
ea5965a 
* main: (30 commits)
  pythongh-103987: fix several crashes in mmap module (python#103990)
  docs: fix wrong indentation causing rendering error in dis page (python#104661)
  pythongh-94906: Support multiple steps in math.nextafter (python#103881)
  pythongh-104472: Skip `test_subprocess.ProcessTestCase.test_empty_env` if ASAN is enabled (python#104667)
  pythongh-103839: Allow building Tkinter against Tcl 8.7 without external libtommath (pythonGH-103842)
  pythongh-85984: New additions and improvements to the tty library. (python#101832)
  pythongh-104659: Consolidate python examples in enum documentation (python#104665)
  pythongh-92248: Deprecate `type`, `choices`, `metavar` parameters of `argparse.BooleanOptionalAction` (python#103678)
  pythongh-104645: fix error handling in marshal tests (python#104646)
  pythongh-104600: Make type.__type_params__ writable (python#104634)
  pythongh-104602: Add additional test for listcomp with lambda (python#104639)
  pythongh-104640: Disallow walrus in comprehension within type scopes (python#104641)
  pythongh-103921: Rename "type" header in argparse docs (python#104654)
  Improve readability of `typing._ProtocolMeta.__instancecheck__` (python#104649)
  pythongh-96522: Fix deadlock in pty.spawn (python#96639)
  pythonGH-102818: Do not call `PyTraceBack_Here` in sys.settrace trampoline.  (pythonGH-104579)
  pythonGH-103545: Add macOS specific constants for ``os.setpriority`` to ``os`` (python#104606)
  pythongh-104623: Update macOS installer to SQLite 3.42.0 (pythonGH-104624)
  pythongh-104619: never leak comprehension locals to outer locals() (python#104637)
  pythongh-104602: ensure all cellvars are known up front (python#104603)
  ...
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees

@JelleZijlstra JelleZijlstra

Labels
type-bug An unexpected behavior, bug, or error
Projects
None yet
Milestone
No milestone
Development

Successfully merging a pull request may close this issue.

gh-104640: Disallow walrus in comprehension within type scopes JelleZijlstra/cpython
1 participant
@JelleZijlstra