BUG: pip install SciPy fails under PyPy

Describe your issue.

I’m seeing this in SymPy CI in https://github.com/sympy/sympy/pull/23859. I don’t immediately have a computer on which I can test this with PyPy locally.

Essentially pip install scipy has failed under PyPy with:

        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/_tags.py", line 79, in __init__
          f'Unknown Python implementation: {self.implementation}. '
      NotImplementedError: Unknown Python implementation: pypy38. Please report this to https://github.com/FFY00/mesonpy/issues and include information about the Python distribution you are using.

You can see the CI setup for this up to the line that fails here: https://github.com/sympy/sympy/blob/7754d037d97d56de9e1bcecb81ecadd4a2e683be/.github/workflows/runtests.yml#L170-L208

The logs for the failed SciPy build are here: https://github.com/sympy/sympy/runs/7583332309?check_suite_focus=true

I have just confirmed that the same CI setup with scipy!=1.9.0 builds 1.8.1 just fine so it seems to be a problem with the 1.9.0 release.

Reproducing Code Example

# Run on Ubuntu 20.04 under PyPy 3.8.
# There might be more to it than this.
# See the CI config above.
pip install scipy

Error message

+ meson install --destdir /tmp/pip-install-pkqrdcy5/scipy_8a1b991ddd494020a114650533cb4ba6/.mesonpy-ve4kjypi/install
      Traceback (most recent call last):
        File "/opt/hostedtoolcache/PyPy/3.8.13/x64/lib/pypy3.8/site-packages/pip/_vendor/pep517/in_process/_in_process.py", line 156, in prepare_metadata_for_build_wheel
          hook = backend.prepare_metadata_for_build_wheel
      AttributeError: module 'mesonpy' has no attribute 'prepare_metadata_for_build_wheel'
      
      During handling of the above exception, another exception occurred:
      
      Traceback (most recent call last):
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/__init__.py", line 714, in _calculate_file_abi_tag_heuristic_posix
          return mesonpy._tags.StableABITag(tag)
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/_tags.py", line 39, in __init__
          raise ValueError(f'Invalid PEP 3149 stable ABI tag, expecting pattern `{self._REGEX.pattern}`')
      ValueError: Invalid PEP 3149 stable ABI tag, expecting pattern `^abi(?P<abi_number>[0-9]+)$`
      
      During handling of the above exception, another exception occurred:
      
      Traceback (most recent call last):
        File "/opt/hostedtoolcache/PyPy/3.8.13/x64/lib/pypy3.8/site-packages/pip/_vendor/pep517/in_process/_in_process.py", line 363, in <module>
          main()
        File "/opt/hostedtoolcache/PyPy/3.8.13/x64/lib/pypy3.8/site-packages/pip/_vendor/pep517/in_process/_in_process.py", line 345, in main
          json_out['return_val'] = hook(**hook_input['kwargs'])
        File "/opt/hostedtoolcache/PyPy/3.8.13/x64/lib/pypy3.8/site-packages/pip/_vendor/pep517/in_process/_in_process.py", line 160, in prepare_metadata_for_build_wheel
          whl_basename = backend.build_wheel(metadata_directory, config_settings)
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/__init__.py", line 927, in build_wheel
          return project.wheel(out).name
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/__init__.py", line 875, in wheel
          wheel = _WheelBuilder(self).build(self._install_plan, self._copy_files, self._build_dir)
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/__init__.py", line 356, in build
          wheel_file = pathlib.Path(directory, f'{self.name}.whl')
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/__init__.py", line 165, in name
          python_tag=self._project.python_tag,
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/__init__.py", line 657, in python_tag
          selected_tag = self._select_abi_tag()
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/__init__.py", line 779, in _select_abi_tag
          tags = self._files_by_tag()
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/__init__.py", line 759, in _files_by_tag
          tag = self._calculate_file_abi_tag_heuristic(file)
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/__init__.py", line 723, in _calculate_file_abi_tag_heuristic
          return self._calculate_file_abi_tag_heuristic_posix(filename)
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/__init__.py", line 716, in _calculate_file_abi_tag_heuristic_posix
          return mesonpy._tags.LinuxInterpreterTag(tag)
        File "/tmp/pip-build-env-mupbdlja/overlay/lib/pypy3.8/site-packages/mesonpy/_tags.py", line 79, in __init__
          f'Unknown Python implementation: {self.implementation}. '
      NotImplementedError: Unknown Python implementation: pypy38. Please report this to https://github.com/FFY00/mesonpy/issues and include information about the Python distribution you are using.

SciPy/NumPy/Python version information

SciPy 1.9.0, PyPy 3.8

[mattip]

See https://foss.heptapod.net/pypy/pypy/-/issues/3870. This was fixed on PyPy HEAD.

[oscarbenjamin]

In SymPy’s case in particular I doubt that testing this setup does much besides detecting upstream bugs. You can question the value of that but apparently it picks up things that are not tested in upstream CI e.g. because SciPy CI doesn’t have anything checking the PyPy build itself.