Refs #35667 -- Cached Django file prefixes for warnings.

3 files changed, 38 insertions, 5 deletions

diff --git a/django/template/base.py b/django/template/base.py
index b87291746b..5e541c3960 100644
--- a/django/template/base.py
+++ b/django/template/base.py
@@ -52,13 +52,12 @@ times with multiple contexts)
 
 import inspect
 import logging
-import os
 import re
 import warnings
 from enum import Enum
 
-import django
 from django.template.context import BaseContext
+from django.utils.deprecation import django_file_prefixes
 from django.utils.formats import localize
 from django.utils.html import conditional_escape
 from django.utils.regex_helper import _lazy_re_compile
@@ -329,7 +328,7 @@ class PartialTemplate:
                 "PartialTemplate.source is only available when template "
                 "debugging is enabled.",
                 RuntimeWarning,
-                skip_file_prefixes=(os.path.dirname(django.__file__),),
+                skip_file_prefixes=django_file_prefixes(),
             )
         return self.find_partial_source(template.source)
 
diff --git a/django/utils/deprecation.py b/django/utils/deprecation.py
index 7d5289bd3c..376eb33fae 100644
--- a/django/utils/deprecation.py
+++ b/django/utils/deprecation.py
@@ -9,6 +9,15 @@ from asgiref.sync import iscoroutinefunction, markcoroutinefunction, sync_to_asy
 import django
 
 
+@functools.cache
+def django_file_prefixes():
+    try:
+        file = django.__file__
+    except AttributeError:
+        return ()
+    return (os.path.dirname(file),)
+
+
 class RemovedInDjango61Warning(DeprecationWarning):
     pass
 
@@ -237,7 +246,7 @@ def deprecate_posargs(deprecation_warning, remappable_names, /):
                 f"Passing positional argument(s) {remapped_names_str} to {func_name}() "
                 "is deprecated. Use keyword arguments instead.",
                 deprecation_warning,
-                skip_file_prefixes=(os.path.dirname(django.__file__),),
+                skip_file_prefixes=django_file_prefixes(),
             )
 
             return remaining_args, updated_kwargs
diff --git a/tests/deprecation/tests.py b/tests/deprecation/tests.py
index 66f6a4d922..3d384b38b7 100644
--- a/tests/deprecation/tests.py
+++ b/tests/deprecation/tests.py
@@ -1,7 +1,32 @@
+import os
 import warnings
 
+import django
 from django.test import SimpleTestCase
-from django.utils.deprecation import RemovedAfterNextVersionWarning, RenameMethodsBase
+from django.utils.deprecation import (
+    RemovedAfterNextVersionWarning,
+    RenameMethodsBase,
+    django_file_prefixes,
+)
+
+
+class DjangoFilePrefixesTests(SimpleTestCase):
+    def setUp(self):
+        django_file_prefixes.cache_clear()
+
+    def test_no_file(self):
+        orig_file = django.__file__
+        try:
+            del django.__file__
+            self.assertEqual(django_file_prefixes(), ())
+        finally:
+            django.__file__ = orig_file
+
+    def test_with_file(self):
+        prefixes = django_file_prefixes()
+        self.assertIsInstance(prefixes, tuple)
+        self.assertEqual(len(prefixes), 1)
+        self.assertTrue(prefixes[0].endswith(f"{os.path.sep}django"))
 
 
 class RenameManagerMethods(RenameMethodsBase):