Incorrect logging in importlib when '.pyc' file creation fails

[qagren]

BPO	35024
Nosy	@brettcannon, @ncoghlan, @ericsnowcurrently, @pablogsal, @miss-islington, @tirkarthi, @qagren, @iritkatriel
PRs	bpo-35024: Remove redundant and possibly incorrect verbose message after writing '.pyc' #9998

^{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 2020-08-18.18:42:10.091>
created_at = <Date 2018-10-19.04:00:41.592>
labels = ['type-bug', 'library']
title = "Incorrect logging in importlib when '.pyc' file creation fails"
updated_at = <Date 2020-08-18.18:42:10.089>
user = 'https://github.com/qagren'

bugs.python.org fields:

activity = <Date 2020-08-18.18:42:10.089>
actor = 'brett.cannon'
assignee = 'none'
closed = True
closed_date = <Date 2020-08-18.18:42:10.091>
closer = 'brett.cannon'
components = ['Library (Lib)']
creation = <Date 2018-10-19.04:00:41.592>
creator = 'qagren'
dependencies = []
files = []
hgrepos = []
issue_num = 35024
keywords = ['patch']
message_count = 4.0
messages = ['328029', '328586', '375569', '375624']
nosy_count = 8.0
nosy_names = ['brett.cannon', 'ncoghlan', 'eric.snow', 'pablogsal', 'miss-islington', 'xtreak', 'qagren', 'iritkatriel']
pr_nums = ['9998']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue35024'
versions = ['Python 3.6']

[qagren]

Hi,

This is the first issue I submit so please correct me if I do anything wrong.

Description of the issue:
imporlib logs 'wrote <path to .pyc file>' even when file creation fails with OSError (for lack of write persmission for example)

Reproducing the bug in Python 3.6 on ubuntu 16.04:

cd /home/quentin/tmp
mkdir __pycache__
chmod -R -w __pycache__
echo '1 + 1' > spam.py
python -vv -c'import spam' 2>&1 | grep '__pycache__/spam'

Output:
# could not create '/home/quentin/tmp/pycache/spam.cpython-36.pyc': PermissionError(13, 'Permission denied')
# wrote '/home/quentin/tmp/pycache/spam.cpython-36.pyc'

Reason:
SourceFileLoader.set_data() silences OSError raised by _write_atomic (importlib/_bootstrap_external.py line 875)
Then SourceLoader.get_code() does not see that something went awry and logs file creation (same file, line 789)

If it is worth fixing I would be glad to contribute a patch, but would probably need a little guidance.

[miss-islington]

New changeset 9e14e49 by Miss Islington (bot) (Quentin Agren) in branch 'master':
bpo-35024: Remove redundant and possibly incorrect verbose message after writing '.pyc' (GH-9998)
9e14e49

[iritkatriel]

This seems resolved, can it be closed?

[brettcannon]

It looks like it! Thanks, Irit!