seqeval build is broken on setuptools<61 (Python 3.8)

[jgerityneurala]

How to reproduce the problem

I noticed this problem while running pip-compile to resolve a dependency graph that includes seqeval, shortly after the 21 Feb 2025 release of setuptools-scm 8.2

Attempt to install seqeval==1.2.2 into a Python environment with setuptools<61, such as a fresh Python 3.8 virtual environment (which will have setuptools 56.0).

$ python3 -V
3.8.14
$ python3 -m venv repro_venv
$ ./repro_venv/bin/python3 -m pip show setuptools | grep Version
Version: 56.0.0
$ ./repro_venv/bin/python3 -m pip install --no-cache seqeval==1.2.2

$ ./repro_venv/bin/python3 -m pip install --no-cache seqeval==1.2.2
$ ./repro_venv/bin/python3 -m pip install --no-cache seqeval==1.2.2
Collecting seqeval==1.2.2
  Downloading seqeval-1.2.2.tar.gz (43 kB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 43.6/43.6 KB 5.4 MB/s eta 0:00:00
  Preparing metadata (setup.py) ... error
  error: subprocess-exited-with-error

  × python setup.py egg_info did not run successfully.
  │ exit code: 1
  ╰─> [73 lines of output]
      WARNING: The wheel package is not available.
      WARNING: The wheel package is not available.
      WARNING: The wheel package is not available.
      WARNING: The wheel package is not available.
      WARNING: The wheel package is not available.
      /tmp/pip-install-u8qnlzk2/seqeval_421dc18d836d45ed8b8fc176526d3cf6/.eggs/setuptools_scm-8.2.0-py3.8.egg/setuptools_scm/_integration/setuptools.py:31: RuntimeWarning:
      ERROR: setuptools==56.0.0 is used in combination with setuptools-scm>=8.x

      Your build configuration is incomplete and previously worked by accident!
      setuptools-scm requires setuptools>=61

      Suggested workaround if applicable:
       - migrating from the deprecated setup_requires mechanism to pep517/518
         and using a pyproject.toml to declare build dependencies
         which are reliably pre-installed before running the build tools

        warnings.warn(
      WARNING setuptools_scm.pyproject_reading toml section missing 'pyproject.toml does not contain a tool.setuptools_scm section'
      Traceback (most recent call last):
        File "/tmp/pip-install-u8qnlzk2/seqeval_421dc18d836d45ed8b8fc176526d3cf6/.eggs/setuptools_scm-8.2.0-py3.8.egg/setuptools_scm/_integration/pyproject_reading.py", line 36, in read_pyproject
          section = defn.get("tool", {})[tool_name]
      KeyError: 'setuptools_scm'
      running egg_info
      creating /tmp/pip-pip-egg-info-fx_p_ap7/seqeval.egg-info
      writing /tmp/pip-pip-egg-info-fx_p_ap7/seqeval.egg-info/PKG-INFO
      writing dependency_links to /tmp/pip-pip-egg-info-fx_p_ap7/seqeval.egg-info/dependency_links.txt
      writing requirements to /tmp/pip-pip-egg-info-fx_p_ap7/seqeval.egg-info/requires.txt
      writing top-level names to /tmp/pip-pip-egg-info-fx_p_ap7/seqeval.egg-info/top_level.txt
      writing manifest file '/tmp/pip-pip-egg-info-fx_p_ap7/seqeval.egg-info/SOURCES.txt'
      Traceback (most recent call last):
...

Note these lines in particular:

      ERROR: setuptools==56.0.0 is used in combination with setuptools-scm>=8.x

      Your build configuration is incomplete and previously worked by accident!
      setuptools-scm requires setuptools>=61

The most straightforward fix to the issue is to add a pyproject.toml declaring setuptools as the build backend, and build isolation will ensure that the building venv ends up with a newer copy of setuptools.

Your Environment

• Operating System: Ubuntu 22.04
• Python Version: Python 3.8
• Package Version: 1.2.2