Refactor check for deprecations in 'setup.py'

Author: abravalheri

setuptools/dist.py

@@ -231,18 +231,6 @@ def check_packages(dist, attr, value):
             )
 
 
-def _check_deprecated_metadata_field(
-    dist: Distribution, attr: str, value: object
-) -> None:
-    if value:
-        SetuptoolsDeprecationWarning.emit(
-            f"Deprecated usage of `{attr}` in setuptools configuration.",
-            see_docs=f"references/keywords.html#keyword-{attr.replace('_', '-')}",
-            due_date=(2027, 1, 25),
-            # Warning initially introduced in 14 Jan 2025
-        )
-
-
 if TYPE_CHECKING:
     # Work around a mypy issue where type[T] can't be used as a base: https://github.com/python/mypy/issues/10962
     from distutils.core import Distribution as _Distribution
@@ -338,9 +326,6 @@ def __init__(self, attrs: MutableMapping[str, Any] | None = None) -> None:
         dist_attrs = {k: v for k, v in attrs.items() if k not in metadata_only}
         _Distribution.__init__(self, dist_attrs)
 
-        for attr in self._DEPRECATED_FIELDS:
-            _check_deprecated_metadata_field(self, attr, dist_attrs.get(attr))
-
         # Private API (setuptools-use only, not restricted to Distribution)
         # Stores files that are referenced by the configuration and need to be in the
         # sdist (e.g. `version = file: VERSION.txt`)
@@ -349,9 +334,9 @@ def __init__(self, attrs: MutableMapping[str, Any] | None = None) -> None:
         self.set_defaults = ConfigDiscovery(self)
 
         self._set_metadata_defaults(attrs)
-
         self.metadata.version = self._normalize_version(self.metadata.version)
         self._finalize_requires()
+        self._check_deprecated_metadata_fields()
 
     def _validate_metadata(self):
         required = {"name"}
@@ -366,6 +351,16 @@ def _validate_metadata(self):
             msg = f"Required package metadata is missing: {missing}"
             raise DistutilsSetupError(msg)
 
+    def _check_deprecated_metadata_fields(self) -> None:
+        for attr in self._DEPRECATED_FIELDS:
+            if getattr(self.metadata, attr, None):
+                anchor = f"keyword-{attr.replace('_', '-')}"
+                SetuptoolsDeprecationWarning.emit(
+                    f"Deprecated usage of `{attr}` in setuptools configuration.",
+                    see_docs=f"references/keywords.html#{anchor}",
+                    due_date=(2027, 1, 25),  # introduced in 20 Jan 2025
+                )
+
     def _set_metadata_defaults(self, attrs):
         """
         Fill-in missing metadata fields not supported by distutils.
@@ -1016,8 +1011,9 @@ def handle_display_options(self, option_order):
 
     def run_command(self, command) -> None:
         self.set_defaults()
-        # Postpone defaults until all explicit configuration is considered
-        # (setup() args, config files, command line and plugins)
+        self._check_deprecated_metadata_fields()
+        # Postpone defaults and validations until all explicit configuration is
+        # considered (setup() args, config files, command line and plugins)
 
         super().run_command(command)