Release the imported settings class during interpreter cleanup

src/dependency_injector/providers.pyx

@@ -45,7 +45,7 @@ except ImportError:
 
 has_pydantic_settings = False
 cdef bint pydantic_v1 = False
-cdef object PydanticSettings = None
+PydanticSettings = None
 cdef str pydantic_module = "pydantic_settings"
 cdef str pydantic_extra = "pydantic2"
 

tests/unit/providers/configuration/test_settings_shutdown.py

@@ -0,0 +1,60 @@
+"""Imported settings classes must participate in interpreter cleanup."""
+
+import subprocess
+import sys
+import textwrap
+
+import pytest
+
+
+@pytest.mark.pydantic
+def test_settings_released_after_exit_callbacks():
+    result = subprocess.run(
+        [
+            sys.executable,
+            "-u",
+            "-c",
+            textwrap.dedent(
+                """
+                import atexit
+                import os
+
+                def check_provider():
+                    config.from_pydantic(Settings(value=43))
+                    assert config.value() == 43
+                    print("EXIT_CALLBACK_OK")
+
+                atexit.register(check_provider)
+                from dependency_injector import providers
+                try:
+                    from pydantic_settings import BaseSettings
+                except ImportError:
+                    from pydantic import BaseSettings
+
+                class Marker:
+                    def __del__(self, write=os.write):
+                        write(1, b"SETTINGS_RELEASED\\n")
+
+                BaseSettings.shutdown_test_marker = Marker()
+
+                class Settings(BaseSettings):
+                    value: int = 42
+
+                config = providers.Configuration()
+                config.from_pydantic(Settings)
+                assert config.value() == 42
+                atexit.register(check_provider)
+                """
+            ),
+        ],
+        capture_output=True,
+        text=True,
+        timeout=30,
+        check=True,
+    )
+    assert result.stdout.splitlines() == [
+        "EXIT_CALLBACK_OK",
+        "EXIT_CALLBACK_OK",
+        "SETTINGS_RELEASED",
+    ]
+    assert result.stderr == ""