Replace error with warning and remove license classifier

Author: cdce8p

setuptools/dist.py

@@ -28,7 +28,6 @@
 from ._reqs import _StrOrIter
 from .config import pyprojecttoml, setupcfg
 from .discovery import ConfigDiscovery
-from .errors import InvalidConfigError
 from .monkey import get_unpatched
 from .warnings import InformationOnly, SetuptoolsDeprecationWarning
 
@@ -414,13 +413,21 @@ def _finalize_license_expression(self) -> None:
                 InformationOnly.emit(f"Normalizing '{license_expr}' to '{normalized}'")
                 self.metadata.license_expression = normalized
 
+            classifiers = []
+            license_classifiers_found = False
             for cl in self.metadata.get_classifiers():
                 if not cl.startswith("License :: "):
+                    classifiers.append(cl)
                     continue
-                raise InvalidConfigError(
-                    "License classifier are deprecated in favor of the license expression. "
-                    f"Remove the '{cl}' classifier."
+                license_classifiers_found = True
+                SetuptoolsDeprecationWarning.emit(
+                    "License classifier are deprecated in favor of the license expression.",
+                    f"Please remove the '{cl}' classifier.",
+                    see_url="https://peps.python.org/pep-0639/",
+                    due_date=(2027, 2, 17),  # Introduced 2025-02-17
                 )
+            if license_classifiers_found:
+                self.metadata.set_classifiers(classifiers)
 
     def _finalize_license_files(self) -> None:
         """Compute names of all license files which should be included."""

setuptools/tests/config/test_apply_pyprojecttoml.py

@@ -9,6 +9,7 @@
 import io
 import re
 import tarfile
+import warnings
 from inspect import cleandoc
 from pathlib import Path
 from unittest.mock import Mock
@@ -23,7 +24,8 @@
 from setuptools.config import expand, pyprojecttoml, setupcfg
 from setuptools.config._apply_pyprojecttoml import _MissingDynamic, _some_attrgetter
 from setuptools.dist import Distribution
-from setuptools.errors import InvalidConfigError, RemovedConfigError
+from setuptools.errors import RemovedConfigError
+from setuptools.warnings import SetuptoolsDeprecationWarning
 
 from .downloads import retrieve_file, urls_from_file
 
@@ -178,6 +180,7 @@ def main_tomatoes(): pass
 license = "mit or apache-2.0"  # should be normalized in metadata
 classifiers = [
     "Development Status :: 5 - Production/Stable",
+    "Programming Language :: Python",
 ]
 """
 
@@ -324,10 +327,19 @@ def test_license_expression_with_bad_classifier(tmp_path):
         "README",
         f"{text}\n    \"License :: OSI Approved :: MIT License\"\n]",
     )
-    msg = "License classifier are deprecated.*'License :: OSI Approved :: MIT License'"
-    with pytest.raises(InvalidConfigError, match=msg):
+    msg = "License classifier are deprecated(?:.|\n)*'License :: OSI Approved :: MIT License'"
+    with pytest.raises(SetuptoolsDeprecationWarning, match=msg):
         pyprojecttoml.apply_configuration(makedist(tmp_path), pyproject)
 
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore", SetuptoolsDeprecationWarning)
+        dist = pyprojecttoml.apply_configuration(makedist(tmp_path), pyproject)
+        # Check 'License :: OSI Approved :: MIT License' is removed
+        assert dist.metadata.get_classifiers() == [
+            "Development Status :: 5 - Production/Stable",
+            "Programming Language :: Python",
+        ]
+
 
 class TestLicenseFiles:
     def base_pyproject(self, tmp_path, additional_text):