Refs #5691 -- Made cache keys independent of USE_L10N.

This mostly reverts af1893c4ff.

django/utils/cache.py

@@ -311,7 +311,7 @@ def has_vary_header(response, header_query):
 
 def _i18n_cache_key_suffix(request, cache_key):
     """If necessary, add the current locale or time zone to the cache key."""
-    if settings.USE_I18N or settings.USE_L10N:
+    if settings.USE_I18N:
         # first check if LocaleMiddleware or another middleware added
         # LANGUAGE_CODE to request, then fall back to the active language
         # which in turn can also fall back to settings.LANGUAGE_CODE
@@ -385,11 +385,11 @@ def learn_cache_key(request, response, cache_timeout=None, key_prefix=None, cach
     if cache is None:
         cache = caches[settings.CACHE_MIDDLEWARE_ALIAS]
     if response.has_header('Vary'):
-        is_accept_language_redundant = settings.USE_I18N or settings.USE_L10N
-        # If i18n or l10n are used, the generated cache key will be suffixed
-        # with the current locale. Adding the raw value of Accept-Language is
-        # redundant in that case and would result in storing the same content
-        # under multiple keys in the cache. See #18191 for details.
+        is_accept_language_redundant = settings.USE_I18N
+        # If i18n is used, the generated cache key will be suffixed with the
+        # current locale. Adding the raw value of Accept-Language is redundant
+        # in that case and would result in storing the same content under
+        # multiple keys in the cache. See #18191 for details.
         headerlist = []
         for header in cc_delim_re.split(response['Vary']):
             header = header.upper().replace('-', '_')

docs/releases/3.2.txt

@@ -336,6 +336,11 @@ Miscellaneous
 
 * Support for ``argon2-cffi`` < 19.1.0 is removed.
 
+* The cache keys no longer includes the language when internationalization is
+  disabled (``USE_I18N = False``) and localization is enabled
+  (``USE_L10N = True``). After upgrading to Django 3.2 in such configurations,
+  the first request to any previously cached value will be a cache miss.
+
 .. _deprecated-features-3.2:
 
 Features deprecated in 3.2

docs/topics/cache.txt

@@ -542,8 +542,7 @@ include the name of the active :term:`language<language code>` -- see also
 :ref:`how-django-discovers-language-preference`). This allows you to easily
 cache multilingual sites without having to create the cache key yourself.
 
-Cache keys also include the active :term:`language <language code>` when
-:setting:`USE_L10N` is set to ``True`` and the :ref:`current time zone
+Cache keys also include the :ref:`current time zone
 <default-current-time-zone>` when :setting:`USE_TZ` is set to ``True``.
 
 __ `Controlling cache: Using other headers`_

tests/cache/tests.py

@@ -1816,7 +1816,7 @@ class CacheI18nTest(SimpleTestCase):
     def tearDown(self):
         cache.clear()
 
-    @override_settings(USE_I18N=True, USE_L10N=False, USE_TZ=False)
+    @override_settings(USE_I18N=True, USE_TZ=False)
     def test_cache_key_i18n_translation(self):
         request = self.factory.get(self.path)
         lang = translation.get_language()
@@ -1837,7 +1837,7 @@ class CacheI18nTest(SimpleTestCase):
         self.assertEqual(key, reference_key)
         self.assertEqual(key2, reference_key)
 
-    @override_settings(USE_I18N=True, USE_L10N=False, USE_TZ=False)
+    @override_settings(USE_I18N=True, USE_TZ=False)
     def test_cache_key_i18n_translation_accept_language(self):
         lang = translation.get_language()
         self.assertEqual(lang, 'en')
@@ -1893,17 +1893,7 @@ class CacheI18nTest(SimpleTestCase):
             key
         )
 
-    @override_settings(USE_I18N=False, USE_L10N=True, USE_TZ=False)
-    def test_cache_key_i18n_formatting(self):
-        request = self.factory.get(self.path)
-        lang = translation.get_language()
-        response = HttpResponse()
-        key = learn_cache_key(request, response)
-        self.assertIn(lang, key, "Cache keys should include the language name when formatting is active")
-        key2 = get_cache_key(request)
-        self.assertEqual(key, key2)
-
-    @override_settings(USE_I18N=False, USE_L10N=False, USE_TZ=True)
+    @override_settings(USE_I18N=False, USE_TZ=True)
     def test_cache_key_i18n_timezone(self):
         request = self.factory.get(self.path)
         tz = timezone.get_current_timezone_name()
@@ -1913,7 +1903,7 @@ class CacheI18nTest(SimpleTestCase):
         key2 = get_cache_key(request)
         self.assertEqual(key, key2)
 
-    @override_settings(USE_I18N=False, USE_L10N=False)
+    @override_settings(USE_I18N=False)
     def test_cache_key_no_i18n(self):
         request = self.factory.get(self.path)
         lang = translation.get_language()