datetime UTC deprecation warnings use the name "datetime" inconsistently

[wjandrea]

Bug report

The UTC deprecation warnings (added in #103858) use the name datetime to refer to both the object and the module, which is confusing. Like, if I copy-paste the code from the warnings, it doesn't work:

>>> import datetime
>>> datetime.datetime.utcnow()
<stdin>:1: DeprecationWarning: datetime.utcnow() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.now(datetime.UTC).
datetime.datetime(2023, 7, 3, 23, 35, 25, 850070)
>>> datetime.now(datetime.UTC)  # <-- Copy-pasted but doesn't work
  ...
AttributeError: module 'datetime' has no attribute 'now'
>>> datetime.datetime.now(datetime.UTC)  # Fixed
datetime.datetime(2023, 7, 3, 23, 35, 32, 898186, tzinfo=datetime.timezone.utc)
>>> 
>>> timestamp = 0
>>> datetime.datetime.utcfromtimestamp(timestamp)
<stdin>:1: DeprecationWarning: datetime.utcfromtimestamp() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.fromtimestamp(timestamp, datetime.UTC).
datetime.datetime(1970, 1, 1, 0, 0)
>>> datetime.fromtimestamp(timestamp, datetime.UTC)  # <-- Copy-pasted but doesn't work
  ...
AttributeError: module 'datetime' has no attribute 'fromtimestamp'
>>> datetime.datetime.fromtimestamp(timestamp, datetime.UTC)  # Fixed
datetime.datetime(1970, 1, 1, 0, 0, tzinfo=datetime.timezone.utc)

To fix it, I'd just put datetime.datetime where necessary. LMK if you want me to submit a PR.

By the way

#104542 brought up the same thing about the deprecated names, but I think it's fine personally:

It's really datetime.datetime.utcnow() and datetime.datetime.utcfromtimestamp(), and not datetime.utcnow() and datetime.utcfromtimestamp().

#105544 might also be relevant, I'm not sure.

Your environment

• CPython versions tested on: 3.12.0b3
• Operating system and architecture: Ubuntu 20.04 x64

Linked PRs

• gh-106392: Fixed datetime UTC deprecation warnings use the name "datetime" inconsistently #106392 (#106392) #106405
• gh-106392: Fix inconsistency in deprecation warnings #106436
• [3.12] gh-106392: Fix inconsistency in deprecation warnings (GH-106436) #108792
• gh-106392: Fix inconsistency in deprecation warnings in datetime module #114761
• gh-106392: Fix consistency in pydatetime error messages #114764
• [3.12] gh-106392: Fix inconsistency in deprecation warnings in datetime module (GH-114761) #114767

[terryjreedy]

The specific inconsistency is that datetime.now(datetime.UTC) uses datetime with two different meanings, first class then module. So the expression can never be correct regardless of the import. I agree with expanding the first datetime to what works with import datetime. This is what @hugovk did with the What'sNew entry. Users should then be able to figure out that the alternative is datetime.now(UTC), with the module label stripped off in both places after both objects are imported from the module.

[hugovk]

@wjandrea Thanks for the report, would you like to create a PR to update the deprecation warning text?

[serhiy-storchaka]

The C implementation was fixed in GH-108073. GH-106436 fixed the Python implementation incompletely, it left inconsistent references to methods at the beginning of warning messages.

[hauntsaninja]

Ah sorry, I was mainly looking at the consistency between datetime.fromtimestamp and datetime.UTC needed to make that expression work, opened #114764