Fix License in pyproject.toml

[eylenburg]

I'm maintaining a Flatpak program that depends on pillow and with the update to version 11.2.1 the Flathub build bot gave me an error.

ValueError: invalid pyproject.toml config: `project.license`.
  configuration error: `project.license` must be valid exactly by one definition (2 matches found):

I think the cause is this commit which adds another license reference so that the license is now referenced as a file and as a text and at least the Flathub builder only allows one.

So my pull request should hopefully fix this problem for Flatpak projects depending on Pillow.

[radarhere]

Hi. Would you be able to determine what version of setuptools you are using?

[eylenburg]

I don't know. I just maintain a Flatpak app that has pillow as a dependency and the Flathub bot wanted to update it from 11.1.0 to 11.2.1 but this resulted in a build error because it found two definition of the project license for pillow.

This is the relevant pull request:
https://github.com/flathub/net.puddletag.puddletag/pull/20/files

[hugovk]

Flathub build bot gave me an error.

The error:

========================================================================
Building module python3-pillow in /srv/buildbot/worker/build-x86_64-4/build/.flatpak-builder/build/python3-pillow-1
========================================================================
�]2;flatpak-builder: Building python3-pillow��]2;flatpak-builder: Installing python3-pillow�Running: pip3 install --verbose --exists-action=i --no-index --find-links="file://${PWD}" --prefix=${FLATPAK_DEST} "pillow" --no-build-isolation
FB: Running 'flatpak build --die-with-parent --env=FLATPAK_BUILDER_BUILDDIR=/run/build/python3-pillow --nofilesystem=host:reset --filesystem=/srv/buildbot/worker/build-x86_64-4/build/.flatpak-builder/build/python3-pillow-1 --bind-mount=/run/build/python3-pillow=/srv/buildbot/worker/build-x86_64-4/build/.flatpak-builder/build/python3-pillow-1 --build-dir=/run/build/python3-pillow --bind-mount=/run/ccache=/srv/buildbot/worker/build-x86_64-4/build/.flatpak-builder/ccache --unshare=network --env=SOURCE_DATE_EPOCH=1744483774 '--env=CFLAGS=-O2 -pipe -g -Wp,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer ' '--env=CXXFLAGS=-O2 -pipe -g -Wp,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer ' '--env=LDFLAGS=-L/app/lib -Wl,-z,relro,-z,now -Wl,--as-needed ' --env=BASEAPP_REMOVE_WEBENGINE=1 --env=CCACHE_DIR=/run/ccache/disabled --env=PATH=/app/bin:/usr/bin --env=LD_LIBRARY_PATH=/app/lib --env=PKG_CONFIG_PATH=/app/lib/pkgconfig:/app/share/pkgconfig:/usr/lib/pkgconfig:/usr/share/pkgconfig --env=FLATPAK_BUILDER_N_JOBS=64 /srv/buildbot/worker/build-x86_64-4/build/.flatpak-builder/rofiles/rofiles-YxhGiX /bin/sh -c 'pip3 install --verbose --exists-action=i --no-index --find-links="file://${PWD}" --prefix=${FLATPAK_DEST} "pillow" --no-build-isolation'' on host
Using pip 25.0.1 from /usr/lib/python3.12/site-packages/pip (python 3.12)
Looking in links: file:///run/build/python3-pillow
Processing ./pillow-11.2.1.tar.gz
  Running command Preparing metadata (pyproject.toml)
  configuration error: `project.license` must be valid exactly by one definition (2 matches found):
      - keys:
          'file': {type: string}
        required: ['file']
      - keys:
          'text': {type: string}
        required: ['text']
  DESCRIPTION:
      `Project license <https://peps.python.org/pep-0621/#license>`_.
  GIVEN VALUE:
      "MIT-CMU"
  OFFENDING RULE: 'oneOf'
  DEFINITION:
      {
          "oneOf": [
              {
                  "properties": {
                      "file": {
                          "type": "string",
                          "$$description": [
                              "Relative path to the file (UTF-8) which contains the license for the",
                              "project."
                          ]
                      }
                  },
                  "required": [
                      "file"
                  ]
              },
              {
                  "properties": {
                      "text": {
                          "type": "string",
                          "$$description": [
                              "The license of the project whose meaning is that of the",
                              "`License field from the core metadata",
                              "<https://packaging.python.org/specifications/core-metadata/#license>`_."
                          ]
                      }
                  },
                  "required": [
                      "text"
                  ]
              }
          ]
      }
  Traceback (most recent call last):
    File "/usr/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 389, in <module>
      main()
    File "/usr/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 373, in main
      json_out["return_val"] = hook(**hook_input["kwargs"])
                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/usr/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 175, in prepare_metadata_for_build_wheel
      return hook(metadata_directory, config_settings)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/usr/lib/python3.12/site-packages/setuptools/build_meta.py", line 377, in prepare_metadata_for_build_wheel
      self.run_setup()
    File "/usr/lib/python3.12/site-packages/setuptools/build_meta.py", line 320, in run_setup
      exec(code, locals())
    File "<string>", line 1053, in <module>
    File "/usr/lib/python3.12/site-packages/setuptools/__init__.py", line 117, in setup
      return distutils.core.setup(**attrs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/usr/lib/python3.12/site-packages/setuptools/_distutils/core.py", line 160, in setup
      dist.parse_config_files()
    File "/usr/lib/python3.12/site-packages/setuptools/dist.py", line 652, in parse_config_files
      pyprojecttoml.apply_configuration(self, filename, ignore_option_errors)
    File "/usr/lib/python3.12/site-packages/setuptools/config/pyprojecttoml.py", line 72, in apply_configuration
      config = read_configuration(filepath, True, ignore_option_errors, dist)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/usr/lib/python3.12/site-packages/setuptools/config/pyprojecttoml.py", line 140, in read_configuration
      validate(subset, filepath)
    File "/usr/lib/python3.12/site-packages/setuptools/config/pyprojecttoml.py", line 61, in validate
      raise ValueError(f"{error}\n{summary}") from None
  ValueError: invalid pyproject.toml config: `project.license`.
  configuration error: `project.license` must be valid exactly by one definition (2 matches found):
      - keys:
          'file': {type: string}
        required: ['file']
      - keys:
          'text': {type: string}
        required: ['text']
  error: subprocess-exited-with-error
  
  × Preparing metadata (pyproject.toml) did not run successfully.
  │ exit code: 1
  ╰─> See above for output.
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
  full command: /usr/bin/python /usr/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py prepare_metadata_for_build_wheel /tmp/tmptk08hvfu
  cwd: /tmp/pip-install-9z6io9hx/pillow_046586ea5fbd47d4b26f9c8d6fcdd86b
  Preparing metadata (pyproject.toml) ... �[?25l�[?25herror
error: metadata-generation-failed
× Encountered error while generating package metadata.
╰─> See above for output.
note: This is an issue with the package mentioned above, not pip.
hint: See above for details.

I think the cause is this commit which adds another license reference so that the license is now referenced as a file and as a text and at least the Flathub builder only allows one.

That commit adds PEP 639 licence metadata: https://peps.python.org/pep-0639/

I think the likely cause is Flathub builder, or something it calls, doesn't support PEP 639 metadata yet.

[radarhere]

Testing, https://buildbot.flathub.org/#/builders/9/builds/18241 showed that it is currently using setuptools 76.0.0.post20250313, rather than >= 77 as cda26be added to the requirements.

March 13 was relatively recent, more recent than any changes to the base https://github.com/flathub/com.riverbankcomputing.PyQt.BaseApp, so I suspect it will update by itself in this corner of the flatpak ecosystem at some point in the near future.

[radarhere]

flathub/com.riverbankcomputing.PyQt.BaseApp#458 was merged. This apparently triggered a setuptools update, and your problem is now resolved.

I created flathub/net.puddletag.puddletag#24 to demonstrate, and you can see that it passed - https://github.com/flathub-infra/vorarbeiter/actions/runs/14653373037