[1.11.x] Fixed #27862 -- Fixed incorrectly quoted table aliases in Subquery SQL.

Add aliases from resolved querysets to the parent query's external
aliases to prevent those aliases from being quoted.

Thanks to Vasily Stepanov for the report and Tim Graham for the review.

Backport of f48bc7c3dbd204eefb3c19016b1e4906ac26bee3 from master

2 files changed, 15 insertions, 1 deletions

diff --git a/django/db/models/expressions.py b/django/db/models/expressions.py
index 01f1333651..a05a1b35ab 100644
--- a/django/db/models/expressions.py
+++ b/django/db/models/expressions.py
@@ -933,10 +933,15 @@ class Subquery(Expression):
 
         def resolve(child):
             if hasattr(child, 'resolve_expression'):
-                return child.resolve_expression(
+                resolved = child.resolve_expression(
                     query=query, allow_joins=allow_joins, reuse=reuse,
                     summarize=summarize, for_save=for_save,
                 )
+                # Add table alias to the parent query's aliases to prevent
+                # quoting.
+                if hasattr(resolved, 'alias'):
+                    clone.queryset.query.external_aliases.add(resolved.alias)
+                return resolved
             return child
 
         resolve_all(clone.queryset.query.where)
diff --git a/tests/expressions/tests.py b/tests/expressions/tests.py
index f6c1c273b7..6e5cf58295 100644
--- a/tests/expressions/tests.py
+++ b/tests/expressions/tests.py
@@ -517,6 +517,15 @@ class BasicExpressionsTests(TestCase):
             [{'salary': 10, 'total_employees': 2300}, {'salary': 20, 'total_employees': 35}],
         )
 
+    def test_subquery_references_joined_table_twice(self):
+        inner = Company.objects.filter(
+            num_chairs__gte=OuterRef('ceo__salary'),
+            num_employees__gte=OuterRef('point_of_contact__salary'),
+        )
+        # Another contrived example (there is no need to have a subquery here)
+        outer = Company.objects.filter(pk__in=Subquery(inner.values('pk')))
+        self.assertFalse(outer.exists())
+
 
 class IterableLookupInnerExpressionsTests(TestCase):
     @classmethod