Fixed #35674 -- Added system check for removed settings.

django/core/checks/__init__.py

@@ -24,6 +24,7 @@ import django.core.checks.model_checks  # NOQA isort:skip
 import django.core.checks.security.base  # NOQA isort:skip
 import django.core.checks.security.csrf  # NOQA isort:skip
 import django.core.checks.security.sessions  # NOQA isort:skip
+import django.core.checks.settings  # NOQA isort:skip
 import django.core.checks.templates  # NOQA isort:skip
 import django.core.checks.translation  # NOQA isort:skip
 import django.core.checks.urls  # NOQA isort:skip

django/core/checks/registry.py

@@ -18,6 +18,7 @@ class Tags:
     files = "files"
     models = "models"
     security = "security"
+    settings = "settings"
     signals = "signals"
     sites = "sites"
     staticfiles = "staticfiles"

django/core/checks/settings.py

@@ -0,0 +1,123 @@
+from django.conf import settings
+
+from . import Tags, Warning, register
+
+REMOVED_SETTINGS = {
+    # Django 1.0
+    # https://docs.djangoproject.com/en/stable/releases/1.0/
+    # Django 1.1
+    # https://docs.djangoproject.com/en/stable/releases/1.1/#features-deprecated-in-1-1
+    # Django 1.2
+    # https://docs.djangoproject.com/en/stable/releases/1.2/#features-deprecated-in-1-2
+    "DATABASE_ENGINE",
+    "DATABASE_HOST",
+    "DATABASE_NAME",
+    "DATABASE_OPTIONS",
+    "DATABASE_PASSWORD",
+    "DATABASE_PORT",
+    "DATABASE_USER",
+    "TEST_DATABASE_CHARSET",
+    "TEST_DATABASE_COLLATION",
+    "TEST_DATABASE_NAME",
+    # Django 1.3
+    # https://docs.djangoproject.com/en/stable/releases/1.3/#features-deprecated-in-1-3
+    # Django 1.4
+    # https://docs.djangoproject.com/en/stable/releases/1.4/#features-deprecated-in-1-4
+    "TRANSACTIONS_MANAGED",
+    # Django 1.5
+    # https://docs.djangoproject.com/en/stable/releases/1.5/#features-deprecated-in-1-5
+    "AUTH_PROFILE_MODULE",
+    # Django 1.7
+    # https://docs.djangoproject.com/en/stable/releases/1.7/#features-removed-in-1-7
+    "SOUTH_DATABASE_ADAPTER",
+    "SOUTH_DATABASE_ADAPTERS",
+    "SOUTH_AUTO_FREEZE_APP",
+    "SOUTH_TESTS_MIGRATE",
+    "SOUTH_LOGGING_ON",
+    "SOUTH_LOGGING_FILE",
+    "SOUTH_MIGRATION_MODULES",
+    "SOUTH_USE_PYC",
+    "TEST_CREATE",
+    "TEST_USER_CREATE",
+    "TEST_PASSWD",
+    "TEST_DATABASE_ENGINE",
+    "TEST_DATABASE_HOST",
+    "TEST_DATABASE_NAME",
+    "TEST_DATABASE_OPTIONS",
+    "TEST_DATABASE_PASSWORD",
+    "TEST_DATABASE_PORT",
+    "TEST_DATABASE_USER",
+    # Django 1.8
+    # https://docs.djangoproject.com/en/stable/releases/1.8/#features-removed-in-1-8
+    "SEND_BROKEN_LINK_EMAILS",
+    "CACHE_MIDDLEWARE_ANONYMOUS_ONLY",
+    # Django 1.9
+    # https://docs.djangoproject.com/en/stable/releases/1.9/#features-removed-in-1-9
+    # Django 1.10
+    # https://docs.djangoproject.com/en/stable/releases/1.10/#features-removed-in-1-10
+    "ALLOWED_INCLUDE_ROOTS",
+    "LOGOUT_URL",
+    "TEMPLATE_CONTEXT_PROCESSORS",
+    "TEMPLATE_DEBUG",
+    "TEMPLATE_DIRS",
+    "TEMPLATE_LOADERS",
+    "TEMPLATE_STRING_IF_INVALID",
+    # Django 2.0
+    # https://docs.djangoproject.com/en/stable/releases/2.0/#features-removed-in-2-0
+    "MIDDLEWARE_CLASSES",
+    # Django 2.1
+    # https://docs.djangoproject.com/en/stable/releases/2.1/#features-removed-in-2-1
+    "USE_ETAGS",
+    "SECURE_BROWSER_XSS_FILTER",
+    # Django 3.0
+    # https://docs.djangoproject.com/en/stable/releases/3.0/#features-removed-in-3-0
+    "DEFAULT_CONTENT_TYPE",
+    "PASSWORD_RESET_TIMEOUT_DAYS",
+    # Django 3.1
+    # https://docs.djangoproject.com/en/stable/releases/3.1/#features-removed-in-3-1
+    "DEFAULT_FILE_STORAGE",
+    "FILE_CHARSET",
+    # Django 4.0
+    # https://docs.djangoproject.com/en/stable/releases/4.0/#features-removed-in-4-0
+    "DEFAULT_HASHING_ALGORITHM",
+    "PASSWORD_RESET_TIMEOUT_DAYS",
+    "SECURE_BROWSER_XSS_FILTER",
+    # Django 4.1
+    # https://docs.djangoproject.com/en/stable/releases/4.1/#features-removed-in-4-1
+    # Django 5.0
+    # https://docs.djangoproject.com/en/stable/releases/5.0/#features-removed-in-5-0
+    "USE_L10N",
+    "USE_DEPRECATED_PYTZ",
+    "CSRF_COOKIE_MASKED",
+    "DATABASE_OPTIONS",
+    # Django 5.1
+    # https://docs.djangoproject.com/en/stable/releases/5.1/#features-removed-in-5-1
+    "DEFAULT_FILE_STORAGE",
+    "STATICFILES_STORAGE",
+    # Django 6.0
+    # RemovedInDjango60Warning: when the deprecation ends, replace with:
+    # "FORMS_URLFIELD_ASSUME_HTTPS",
+}
+
+
+@register(Tags.settings)
+def check_removed_settings(**kwargs):
+    """
+    This check warns users who still use deprecated settings variables.
+    """
+
+    warnings = []
+    for setting_name in dir(settings):
+        if setting_name.isupper() and setting_name in REMOVED_SETTINGS:
+            warnings.append(
+                Warning(
+                    f"The {setting_name!r} setting was removed and its use is "
+                    f"not recommended.",
+                    hint="Please refer to the documentation and remove/replace "
+                    "this setting.",
+                    obj=setting_name,
+                    id="settings.W001",
+                )
+            )
+
+    return warnings

docs/ref/checks.txt

@@ -120,6 +120,12 @@ upgrading Django.
   :setting:`CSRF_TRUSTED_ORIGINS` setting must start with a scheme (usually
   ``http://`` or ``https://``) but found ``<hostname>``.
 
+Removed setting variables
+-------------------------
+
+* **settings.W001**: The ``<name>`` setting was removed and its use is not
+  recommended.
+
 Caches
 ------
 

docs/releases/5.2.txt

@@ -291,6 +291,13 @@ Signals
 
 * ...
 
+System checks
+~~~~~~~~~~~~~
+
+* Added a new system check for detecting removed Django setting variables.
+  This check will point out all usages of known removals starting from
+  Django v1.0 and will raise a **settings.W001** warning.
+
 Templates
 ~~~~~~~~~
 

tests/check_framework/test_settings.py

@@ -0,0 +1,23 @@
+from django.apps import apps
+from django.core import checks
+from django.test import SimpleTestCase, override_settings
+
+
+class RemovedSettingsCheckTests(SimpleTestCase):
+    @override_settings(TRANSACTIONS_MANAGED=True)
+    def test_check_removed_settings(self):
+        all_issues = checks.run_checks(app_configs=apps.get_app_configs())
+
+        self.assertGreater(len(all_issues), 0)
+
+        self.assertIn(
+            checks.Warning(
+                "The 'TRANSACTIONS_MANAGED' setting was removed and its use "
+                "is not recommended.",
+                hint="Please refer to the documentation and remove/replace "
+                "this setting.",
+                obj="TRANSACTIONS_MANAGED",
+                id="settings.W001",
+            ),
+            all_issues,
+        )