ast.Constant.n deprecated without warning

@jwilk

BPO	46797
Nosy	@jwilk, @serhiy-storchaka
PRs	gh-90953: Emit deprecation warnings for deprecated ast features #31432

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2022-02-19.08:29:16.968>
labels = ['library', '3.11']
title = 'ast.Constant.n deprecated without warning'
updated_at = <Date 2022-02-19.12:24:07.912>
user = 'https://github.com/jwilk'

bugs.python.org fields:

activity = <Date 2022-02-19.12:24:07.912>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2022-02-19.08:29:16.968>
creator = 'jwilk'
dependencies = []
files = []
hgrepos = []
issue_num = 46797
keywords = ['patch']
message_count = 2.0
messages = ['413541', '413546']
nosy_count = 2.0
nosy_names = ['jwilk', 'serhiy.storchaka']
pr_nums = ['31432']
priority = 'low'
resolution = 'postponed'
stage = 'patch review'
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue46797'
versions = ['Python 3.11']

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ast.Constant.n is documented to be deprecated, but you don't get any warning when you use it:

$ python3.11 -Wd
Python 3.11.0a5 (main, Feb 12 2022, 17:11:59) [GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import ast
>>> help(ast.Constant.n)
Help on property:

Deprecated. Use value instead.

>>> ast.Constant(value=42).n
42

It is because we did not have a plan for removing deprecates features. Deprecation in documentation only helps third-party code. Instead of adding a complex code which switches between using old and new names depending on Python version, the third-party code can continue to use old names without worring about deprecation warnings, and switch completely to using new features only when support of old Python versions be dropped. 3.7 and 3.8 are not so old and may be still supported in third-party code.

I have created a PR which adds deprecation warnings, but I am not sure that it is worth to include it in 3.11.

gh-90953: Emit deprecation warnings for `ast` features deprecated in …

pythongh-90953: Emit deprecation warnings for `ast` features deprecat…

pythongh-90953: Don't use deprecated AST nodes in clinic.py

gh-90953: Don't use deprecated AST nodes in clinic.py (#104322)

Merge branch 'main' into fixloadsuperspec

A deprecation warning is now raised:

Python 3.12.1 (v3.12.1:2305ca5144, Dec  7 2023, 17:23:38) [Clang 13.0.0 (clang-1300.0.29.30)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import ast
>>> help(ast.Constant.n)
Help on property:

    Deprecated. Use value instead.

>>> ast.Constant(value=42).n
<stdin>:1: DeprecationWarning: Attribute n is deprecated and will be removed in Python 3.14; use value instead
42

Replace `ast.Num` with `ast.Constant`

pythongh-90953: Don't use deprecated AST nodes in clinic.py (pythonGH…

[3.10] gh-90953: Don't use deprecated AST nodes in clinic.py (GH-104322…

[3.9] gh-90953: Don't use deprecated AST nodes in clinic.py (GH-104322)…

[3.11] gh-90953: Don't use deprecated AST nodes in clinic.py (GH-104322…

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ast.Constant.n deprecated without warning #90953

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ast.Constant.n deprecated without warning #90953

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jwilk commented on Feb 19, 2022

serhiy-storchaka commented on Feb 19, 2022

hugovk commented on Jan 11, 2024

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