Fixed #20874 -- bump_prefix() in nested subqueries

Also made some cleanup to build_filter() code by introducing submethods
solve_lookup_type() and prepare_lookup_value().

2 files changed, 32 insertions, 3 deletions

diff --git a/tests/foreign_object/tests.py b/tests/foreign_object/tests.py
index cd81cc68a2..77582162a8 100644
--- a/tests/foreign_object/tests.py
+++ b/tests/foreign_object/tests.py
@@ -132,7 +132,6 @@ class MultiColumnFKTests(TestCase):
             ],
             attrgetter('person_id')
         )
-
         self.assertQuerysetEqual(
             Membership.objects.filter(person__in=Person.objects.filter(name='Jim')), [
                 self.jim.id,
@@ -140,6 +139,24 @@ class MultiColumnFKTests(TestCase):
             attrgetter('person_id')
         )
 
+    def test_double_nested_query(self):
+        m1 = Membership.objects.create(membership_country_id=self.usa.id, person_id=self.bob.id,
+                                       group_id=self.cia.id)
+        m2 = Membership.objects.create(membership_country_id=self.usa.id, person_id=self.jim.id,
+                                       group_id=self.cia.id)
+        Friendship.objects.create(from_friend_country_id=self.usa.id, from_friend_id=self.bob.id,
+                                  to_friend_country_id=self.usa.id, to_friend_id=self.jim.id)
+        self.assertQuerysetEqual(Membership.objects.filter(
+            person__in=Person.objects.filter(
+                from_friend__in=Friendship.objects.filter(
+                    to_friend__in=Person.objects.all()))),
+            [m1], lambda x: x)
+        self.assertQuerysetEqual(Membership.objects.exclude(
+            person__in=Person.objects.filter(
+                from_friend__in=Friendship.objects.filter(
+                    to_friend__in=Person.objects.all()))),
+            [m2], lambda x: x)
+
     def test_select_related_foreignkey_forward_works(self):
         Membership.objects.create(membership_country=self.usa, person=self.bob, group=self.cia)
         Membership.objects.create(membership_country=self.usa, person=self.jim, group=self.democrat)
diff --git a/tests/queries/tests.py b/tests/queries/tests.py
index 6e03b0d7f6..cd47f0ccd5 100644
--- a/tests/queries/tests.py
+++ b/tests/queries/tests.py
@@ -27,7 +27,6 @@ from .models import (
     BaseA, FK1, Identifier, Program, Channel, Page, Paragraph, Chapter, Book,
     MyObject, Order, OrderItem)
 
-
 class BaseQuerysetTest(TestCase):
     def assertValueQuerysetEqual(self, qs, values):
         return self.assertQuerysetEqual(qs, values, transform=lambda x: x)
@@ -84,6 +83,19 @@ class Queries1Tests(BaseQuerysetTest):
         Cover.objects.create(title="first", item=i4)
         Cover.objects.create(title="second", item=self.i2)
 
+    def test_subquery_condition(self):
+        qs1 = Tag.objects.filter(pk__lte=0)
+        qs2 = Tag.objects.filter(parent__in=qs1)
+        qs3 = Tag.objects.filter(parent__in=qs2)
+        self.assertEqual(qs3.query.subq_aliases, set(['T', 'U', 'V']))
+        self.assertIn('V0', str(qs3.query))
+        qs4 = qs3.filter(parent__in=qs1)
+        self.assertEqual(qs4.query.subq_aliases, set(['T', 'U', 'V']))
+        # It is possible to reuse U for the second subquery, no need to use W.
+        self.assertNotIn('W0', str(qs4.query))
+        # So, 'U0."id"' is referenced twice.
+        self.assertTrue(str(qs4.query).count('U0."id"'), 2)
+
     def test_ticket1050(self):
         self.assertQuerysetEqual(
             Item.objects.filter(tags__isnull=True),
@@ -810,7 +822,7 @@ class Queries1Tests(BaseQuerysetTest):
         # Make sure bump_prefix() (an internal Query method) doesn't (re-)break. It's
         # sufficient that this query runs without error.
         qs = Tag.objects.values_list('id', flat=True).order_by('id')
-        qs.query.bump_prefix()
+        qs.query.bump_prefix(qs.query)
         first = qs[0]
         self.assertEqual(list(qs), list(range(first, first+5)))