Drop support for Python 3.11

[tiran]

Fromager currently supports Python >= 3.11. I propose to drop support for Python 3.11 and make Python 3.12 the minimum supported Python version. It would allow us to use Python 3.12 features and reduce our test matrix.

In upstream, Python 3.11 is in security-fix only mode. In downstream, we have stopped using Python 3.11 a while ago. Python 3.11 in RHEL 9 is reaching end of support in a few months.

https://docs.python.org/3/whatsnew/3.12.html#improved-modules

[tiran]

Download stats for Python 3.11 vs. 3.12 from https://pypistats.org/packages/fromager

[LalatenduMohanty]

I am fine with dropping 3.11 support. @dhellmann @rd4398 WDYT?

[dhellmann]

I am fine with dropping 3.11 support. @dhellmann @rd4398 WDYT?

Fine with me.

[LalatenduMohanty]

FYI, this issue is blocking #947

[tiran]

• remove 3.11 tests from GitHub Actions
• update classifiers in pyproject.toml
• update [tool.ruff] target-version = "py311" and then let ruff check --fix do the fixing

[shifa-khan]

The reason I unassigned myself is that Shanmukh mentioned he has the fix locally. He’s just waiting to be added to the org so he can push the changes.

[smoparth]

The core 3.11 drop changes are ready. CI matrix, pyproject.toml classifiers, requires-python, ruff target-version, Mergify config.

1. Documentation references:
   docs/quickstart.rst
   CONTRIBUTING.md
   docs/example/Containerfile
   docs/how-tos/containers.rst and docs/getting-started.rst
   The first three are straightforward text fixes. The last two are example output logs that would need to be regenerated by re-running the examples, needs some time.

2. After bumping target-version to py312 in ruff config, I ran hatch run lint:fix. Formatting produced no changes, but ruff check now flags 7 UP040 violations — type aliases that should use the Python 3.12 type keyword instead of typing.TypeAlias:

smoparth@smoparth-mac fromager % hatch run lint:fix
cmd [1] | ruff format src tests docs
92 files left unchanged
cmd [2] | ruff check --fix src tests docs
UP040 Type alias `BuildSequenceEntryFuture` uses `TypeAlias` annotation instead of the `type` keyword
  --> src/fromager/commands/build.py:61:1
   |
61 | / BuildSequenceEntryFuture: typing.TypeAlias = concurrent.futures.Future[
62 | |     BuildSequenceEntry
63 | | ]
   | |_^
64 |   DependencyNodeSet: typing.TypeAlias = set[dependency_graph.DependencyNode]
   |
help: Use the `type` keyword

UP040 Type alias `DependencyNodeSet` uses `TypeAlias` annotation instead of the `type` keyword
  --> src/fromager/commands/build.py:64:1
   |
62 |     BuildSequenceEntry
63 | ]
64 | DependencyNodeSet: typing.TypeAlias = set[dependency_graph.DependencyNode]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
help: Use the `type` keyword

UP040 Type alias `RequirementsMap` uses `TypeAlias` annotation instead of the `type` keyword
   --> src/fromager/resolver.py:372:1
    |
372 | RequirementsMap: typing.TypeAlias = typing.Mapping[str, typing.Iterable[Requirement]]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
373 | Candidates: typing.TypeAlias = typing.Iterable[Candidate]
374 | CandidatesMap: typing.TypeAlias = typing.Mapping[str, Candidates]
    |
help: Use the `type` keyword

UP040 Type alias `Candidates` uses `TypeAlias` annotation instead of the `type` keyword
   --> src/fromager/resolver.py:373:1
    |
372 | RequirementsMap: typing.TypeAlias = typing.Mapping[str, typing.Iterable[Requirement]]
373 | Candidates: typing.TypeAlias = typing.Iterable[Candidate]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
374 | CandidatesMap: typing.TypeAlias = typing.Mapping[str, Candidates]
375 | # {identifier: [cls, cachekey]: list[candidates]}}
    |
help: Use the `type` keyword

UP040 Type alias `CandidatesMap` uses `TypeAlias` annotation instead of the `type` keyword
   --> src/fromager/resolver.py:374:1
    |
372 | RequirementsMap: typing.TypeAlias = typing.Mapping[str, typing.Iterable[Requirement]]
373 | Candidates: typing.TypeAlias = typing.Iterable[Candidate]
374 | CandidatesMap: typing.TypeAlias = typing.Mapping[str, Candidates]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
375 | # {identifier: [cls, cachekey]: list[candidates]}}
376 | ResolverCache: typing.TypeAlias = dict[
    |
help: Use the `type` keyword

UP040 Type alias `ResolverCache` uses `TypeAlias` annotation instead of the `type` keyword
   --> src/fromager/resolver.py:376:1
    |
374 |   CandidatesMap: typing.TypeAlias = typing.Mapping[str, Candidates]
375 |   # {identifier: [cls, cachekey]: list[candidates]}}
376 | / ResolverCache: typing.TypeAlias = dict[
377 | |     str, dict[tuple[type[ExtrasProvider], str], list[Candidate]]
378 | | ]
    | |_^
379 |   VersionSource: typing.TypeAlias = typing.Callable[
380 |       [str],
    |
help: Use the `type` keyword

UP040 Type alias `VersionSource` uses `TypeAlias` annotation instead of the `type` keyword
   --> src/fromager/resolver.py:379:1
    |
377 |       str, dict[tuple[type[ExtrasProvider], str], list[Candidate]]
378 |   ]
379 | / VersionSource: typing.TypeAlias = typing.Callable[
380 | |     [str],
381 | |     typing.Iterable[Candidate | tuple[str, str | Version]],
382 | | ]
    | |_^
    |
help: Use the `type` keyword

Found 7 errors.
No fixes available (7 hidden fixes can be enabled with the `--unsafe-fixes` option).

The affected code:
src/fromager/commands/build.py — 2 type aliases (BuildSequenceEntryFuture, DependencyNodeSet)
src/fromager/resolver.py — 5 type aliases (RequirementsMap, Candidates, CandidatesMap, ResolverCache, VersionSource)

Should I address these in the same PR as a separate commit, or open a follow-up PR?

@LalatenduMohanty , @tiran

[LalatenduMohanty]

@smoparth Please send a PR