Fix locate_file() type hints for older Pythons

[ichard26]

🤦

See #11685 (comment).

Admittedly, _PIP_USE_IMPORTLIB_METADATA is probably pretty rare and the backend seems to be broken on the older Pythons already, but it can work in some limited situations. Unless people complain on mass, this doesn't warrant a bugfix release.

[ichard26]

I'm not a huge fan of this wording as it seems to be actually still broken on the older Pythons, but that is the risk when you try to use a private envvar...

Obtaining file:///home/ichard26/dev/oss/pip
  Installing build dependencies ... error
  error: subprocess-exited-with-error
  
  × pip subprocess to install build dependencies did not run successfully.
  │ exit code: 2
  ╰─> [53 lines of output]
      Collecting setuptools>=67.6.1
        Using cached setuptools-75.8.0-py3-none-any.whl.metadata (6.7 kB)
      ERROR: Exception:
      Traceback (most recent call last):
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/cli/base_command.py", line 105, in _run_wrapper
          status = _inner_run()
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/cli/base_command.py", line 96, in _inner_run
          return self.run(options, args)
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/cli/req_command.py", line 67, in wrapper
          return func(self, options, args)
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/commands/install.py", line 379, in run
          requirement_set = resolver.resolve(
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/resolution/resolvelib/resolver.py", line 95, in resolve
          result = self._result = resolver.resolve(
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_vendor/resolvelib/resolvers.py", line 546, in resolve
          state = resolution.resolve(requirements, max_rounds=max_rounds)
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_vendor/resolvelib/resolvers.py", line 397, in resolve
          self._add_to_criteria(self.state.criteria, r, parent=None)
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_vendor/resolvelib/resolvers.py", line 173, in _add_to_criteria
          if not criterion.candidates:
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_vendor/resolvelib/structs.py", line 156, in __bool__
          return bool(self._sequence)
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/resolution/resolvelib/found_candidates.py", line 174, in __bool__
          return any(self)
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/resolution/resolvelib/found_candidates.py", line 162, in <genexpr>
          return (c for c in iterator if id(c) not in self._incompatible_ids)
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/resolution/resolvelib/found_candidates.py", line 53, in _iter_built
          candidate = func()
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/resolution/resolvelib/factory.py", line 187, in _make_candidate_from_link
          base: Optional[BaseCandidate] = self._make_base_candidate_from_link(
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/resolution/resolvelib/factory.py", line 233, in _make_base_candidate_from_link
          self._link_candidate_cache[link] = LinkCandidate(
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/resolution/resolvelib/candidates.py", line 304, in __init__
          super().__init__(
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/resolution/resolvelib/candidates.py", line 159, in __init__
          self.dist = self._prepare()
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/resolution/resolvelib/candidates.py", line 236, in _prepare
          dist = self._prepare_distribution()
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/resolution/resolvelib/candidates.py", line 315, in _prepare_distribution
          return preparer.prepare_linked_requirement(self._ireq, parallel_builds=True)
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/operations/prepare.py", line 521, in prepare_linked_requirement
          metadata_dist = self._fetch_metadata_only(req)
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/operations/prepare.py", line 373, in _fetch_metadata_only
          return self._fetch_metadata_using_link_data_attr(
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/operations/prepare.py", line 412, in _fetch_metadata_using_link_data_attr
          if canonicalize_name(metadata_dist.raw_name) != canonicalize_name(req.req.name):
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/metadata/base.py", line 419, in raw_name
          return self.metadata.get("Name", self.canonical_name)
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/metadata/importlib/_dists.py", line 162, in canonical_name
          return get_dist_canonical_name(self._dist)
        File "/home/ichard26/.local/share/vem/envs/pip-20250126-105715/lib/python3.9/site-packages/pip/_internal/metadata/importlib/_compat.py", line 82, in get_dist_canonical_name
          name = cast(Any, dist).name
      AttributeError: 'PathDistribution' object has no attribute 'name'
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.

[notice] A new release of pip is available: 24.3.1 -> 25.0
[notice] To update, run: pip install --upgrade pip
error: subprocess-exited-with-error

× pip subprocess to install build dependencies did not run successfully.
│ exit code: 2
╰─> See above for output.

note: This error originates from a subprocess, and is likely not a problem with pip.

[jsirois]

LGTM

[notatallshaw]

This linting rule would have picked this up: https://docs.astral.sh/ruff/rules/future-required-type-annotation/

Worth enabling? I can create a seperate PR. It also picks up 3 issues in build-project.py which I guess is not Python 3.8/3.9 compatible.

[ichard26]

Please :)

[notatallshaw]

IMO this is safe to land onto main (and the follow up #13182), all the methods are internal and so not exposed to outside consumers with any guarantees, and even then it shouldn't affect any consumers as it doesn't change the semantics of the type hints, it just uses more compatible syntax.

But I ofcourse leave that to @sbidoul to judge.