del __debug__ should be a SyntaxError

[aroberge]

BPO	45000
Nosy	@aroberge, @corona10, @lysnikolaou, @pablogsal, @miss-islington
PRs	bpo-45000: Raise SyntaxError when try to delete __debug__ #27947 bpo-45000: Update whatsnews about deleting __debug__ #27956 [3.10] bpo-45000: Raise SyntaxError when try to delete __debug__ (GH-27947) #27957 [3.10] bpo-45000: Update whatsnews about deleting __debug__ (GH-27956). #27958

^{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 = None
closed_at = <Date 2021-08-26.09:52:32.700>
created_at = <Date 2021-08-25.11:50:39.044>
labels = ['interpreter-core', 'type-bug', '3.10', '3.11']
title = 'del __debug__ should be a SyntaxError'
updated_at = <Date 2021-08-26.09:52:32.699>
user = 'https://github.com/aroberge'

bugs.python.org fields:

activity = <Date 2021-08-26.09:52:32.699>
actor = 'pablogsal'
assignee = 'none'
closed = True
closed_date = <Date 2021-08-26.09:52:32.700>
closer = 'pablogsal'
components = ['Parser']
creation = <Date 2021-08-25.11:50:39.044>
creator = 'aroberge'
dependencies = []
files = []
hgrepos = []
issue_num = 45000
keywords = ['patch']
message_count = 5.0
messages = ['400256', '400277', '400302', '400331', '400332']
nosy_count = 5.0
nosy_names = ['aroberge', 'corona10', 'lys.nikolaou', 'pablogsal', 'miss-islington']
pr_nums = ['27947', '27956', '27957', '27958']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue45000'
versions = ['Python 3.10', 'Python 3.11']

[aroberge]

Consider the following:

Python 3.10.0rc1  ...
>>> __debug__
True
>>> del __debug__
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name '__debug__' is not defined
>>> __debug__
True
>>> __debug__ = False
  File "<stdin>", line 1
SyntaxError: cannot assign to __debug__

I suggest that attempting to delete __debug__ should be a SyntaxError, similar to attempting to delete None and other constants.

>>> del None
  File "<stdin>", line 1
    del None
        ^^^^
SyntaxError: cannot delete None

= = =
The same NameError exception is raised for Python 3.9 when attempting to delete __debug__. For Python 3.8, attempting to delete __debug__ silently fails, so the current behaviour is at least an improvement.

[miss-islington]

New changeset 551da59 by Dong-hee Na in branch 'main':
bpo-45000: Raise SyntaxError when try to delete __debug__ (GH-27947)
551da59

[corona10]

New changeset c764dfb by Dong-hee Na in branch 'main':
bpo-45000: Update whatsnews about deleting __debug__ (GH-27956)
c764dfb

[pablogsal]

New changeset 6ea6cf2 by Dong-hee Na in branch '3.10':
[3.10] bpo-45000: Update whatsnews about deleting __debug__ (GH-27956) (GH-27958)
6ea6cf2

[pablogsal]

New changeset 32c1caa by Dong-hee Na in branch '3.10':
bpo-45000: Raise SyntaxError when try to delete __debug__ (GH-27947) (GH-27957)
32c1caa