[regression] symtable.Symbol.is_local() is no longer True for bound global symbols

[CendioOssman]

BPO	41840
Nosy	@pablogsal, @CendioOssman
PRs	bpo-41840: Report module-level globals as both local and global in the symtable module #22391 [3.9] bpo-41840: Report module-level globals as both local and global in the symtable module (GH-22391) #22528 [3.8] bpo-41840: Report module-level globals as both local and global in the symtable module (GH-22391) #22529

^{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 2020-10-03.21:49:56.503>
created_at = <Date 2020-09-23.12:22:04.951>
labels = ['3.8', '3.7', 'library', '3.9', '3.10']
title = '[regression] symtable.Symbol.is_local() is no longer True for bound global symbols'
updated_at = <Date 2020-10-03.21:50:03.298>
user = 'https://github.com/CendioOssman'

bugs.python.org fields:

activity = <Date 2020-10-03.21:50:03.298>
actor = 'pablogsal'
assignee = 'none'
closed = True
closed_date = <Date 2020-10-03.21:49:56.503>
closer = 'pablogsal'
components = ['Library (Lib)']
creation = <Date 2020-09-23.12:22:04.951>
creator = 'CendioOssman'
dependencies = []
files = []
hgrepos = []
issue_num = 41840
keywords = ['patch']
message_count = 5.0
messages = ['377373', '377428', '377901', '377903', '377904']
nosy_count = 2.0
nosy_names = ['pablogsal', 'CendioOssman']
pr_nums = ['22391', '22528', '22529']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue41840'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8', 'Python 3.9', 'Python 3.10']

[CendioOssman]

So bpo-40196 (and PR 19391) broke things for us here as Symbol.is_local() no longer works properly for symbols on the global/module scope.

Previously it would return True for all global symbols that were bound. Now it only returns True when the symbol is not used in any other scope. This means we cannot tell the difference between globals that are from the module itself, and globals that come in via imports.

This also seems to contradict this part of the language reference:

"(The variables of the module code block are local and global.)"

https://docs.python.org/3/reference/executionmodel.html

I don't see any clean workaround as there is no Symbol.is_bound() that could be used instead.

(inb4 https://xkcd.com/1172/)

[pablogsal]

Hi Cendio Ossman and thanks for the report.

Indeed, there are a bunch of problems here taking into account the language reference "The variables of the module code block are local and global". PR 22391 fixes those and also the repr-generation for module-level that was also broken

[pablogsal]

New changeset fb0a465 by Pablo Galindo in branch 'master':
bpo-41840: Report module-level globals as both local and global in the symtable module (GH-22391)
fb0a465

[pablogsal]

New changeset 7b7aa94 by Pablo Galindo in branch '3.9':
[3.9] bpo-41840: Report module-level globals as both local and global in the symtable module (GH-22391). (GH-22528)
7b7aa94

[pablogsal]

New changeset fd22823 by Pablo Galindo in branch '3.8':
[3.8] bpo-41840: Report module-level globals as both local and global in the symtable module (GH-22391). (GH-22529)
fd22823