Refs #27149 -- Based recursive nested subquery detection on sys.getrecursionlimit().

This makes sure the test_avoid_infinite_loop_on_too_many_subqueries test
doesn't fail on systems with a non-default recursion limit.

django/db/models/sql/query.py

@@ -9,6 +9,7 @@ all about the internals of models in order to get the information it needs.
 import difflib
 import functools
 import inspect
+import sys
 import warnings
 from collections import Counter, namedtuple
 from collections.abc import Iterator, Mapping
@@ -883,7 +884,11 @@ class Query(BaseExpression):
             # No clashes between self and outer query should be possible.
             return
 
-        local_recursion_limit = 67  # explicitly avoid infinite loop
+        # Explicitly avoid infinite loop. The constant divider is based on how
+        # much depth recursive subquery references add to the stack. This value
+        # might need to be adjusted when adding or removing function calls from
+        # the code path in charge of performing these operations.
+        local_recursion_limit = sys.getrecursionlimit() // 16
         for pos, prefix in enumerate(prefix_gen()):
             if prefix not in self.subq_aliases:
                 self.alias_prefix = prefix

tests/queries/tests.py

@@ -1,5 +1,6 @@
 import datetime
 import pickle
+import sys
 import unittest
 from operator import attrgetter
 
@@ -402,10 +403,10 @@ class Queries1Tests(TestCase):
 
     def test_avoid_infinite_loop_on_too_many_subqueries(self):
         x = Tag.objects.filter(pk=1)
-        local_recursion_limit = 67
+        local_recursion_limit = sys.getrecursionlimit() // 16
         msg = 'Maximum recursion depth exceeded: too many subqueries.'
         with self.assertRaisesMessage(RuntimeError, msg):
-            for i in range(local_recursion_limit * 2):
+            for i in range(local_recursion_limit + 2):
                 x = Tag.objects.filter(pk__in=x)
 
     def test_reasonable_number_of_subq_aliases(self):