replace usage of peppyproject with simply reading pyproject.toml

Author: zacharyburnett

.github/workflows/tox.yml

@@ -156,7 +156,7 @@ jobs:
       - if: inputs.fill
         run: echo $SUPPORTED_PYTHONS_SCRIPT | base64 --decode > supported_pythons.py
         env:
-          SUPPORTED_PYTHONS_SCRIPT: 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
+          SUPPORTED_PYTHONS_SCRIPT: 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
       - if: inputs.fill # zizmor: ignore[template-injection]
         id: supported-pythons
         run: uv run supported_pythons.py --package-source . ${{ inputs.fill_platforms != '' && format('--platforms {0}', inputs.fill_platforms) || '' }} ${{ inputs.fill_factors != '' && format('--factors {0}', inputs.fill_factors) || '' }}

tools/supported_pythons.py

@@ -2,9 +2,9 @@
 # requires-python = ">=3.12"
 # dependencies = [
 #     "click==8.2.1",
-#     "peppyproject==1.0.2",
-#     "requests==2.32.5",
 #     "packaging==25.0",
+#     "requests==2.32.5",
+#     "tomli==2.4.0",
 # ]
 # ///
 import os
@@ -13,9 +13,9 @@
 
 import click
 import requests
+import tomli
 from packaging.specifiers import SpecifierSet
 from packaging.version import Version
-from peppyproject import PyProjectConfiguration
 
 
 @click.command()
@@ -69,19 +69,38 @@ def supported_pythons(
     if not package_source:
         supported_versions = current_python_versions
     else:
-        configuration = PyProjectConfiguration.from_directory(package_source)
         try:
-            python_version_requirements = SpecifierSet(configuration["project"]["requires-python"])
+            pyproject_toml_filename = Path(package_source) / "pyproject.toml"
+            if pyproject_toml_filename.exists():
+                with open(pyproject_toml_filename, "rb") as pyproject_toml_file:
+                    pyproject_toml = tomli.load(pyproject_toml_file)
+                if "project" in pyproject_toml:
+                    project_metadata = pyproject_toml["table"]
+                    if "requires_python" in project_metadata:
+                        python_version_requirements = SpecifierSet(
+                            project_metadata["requires-python"]
+                        )
+                    else:
+                        raise KeyError(
+                            "`project.requires_python` not found in `pyproject.toml`; ensure your package conforms to PEP621"
+                        )
+                else:
+                    raise KeyError(
+                        "`project` not found in `pyproject.toml`; ensure your package conforms to PEP621"
+                    )
+            else:
+                raise FileNotFoundError(
+                    "could not find `pyproject.toml` in the provided package source; ensure your package conforms to PEP621"
+                )
 
             supported_versions = [
                 python_version
                 for python_version in current_python_versions
                 if python_version in python_version_requirements
             ]
-        except (KeyError, TypeError):
-            warnings.warn(
-                "could not find `requires-python` in metadata; falling back to current Python versions..."
-            )
+        except (KeyError, TypeError, FileNotFoundError) as error:
+            warnings.warn(str(error))
+            warnings.warn("falling back to current Python versions...")
             supported_versions = current_python_versions
 
     return supported_versions