Refs #34551 -- Fixed QuerySet.aggregate() crash on precending aggregation reference.

Regression in 1297c0d0d76a708017fe196b61a0ab324df76954.

Refs #31679.

2 files changed, 22 insertions, 3 deletions

diff --git a/django/db/models/aggregates.py b/django/db/models/aggregates.py
index e672f0aeb0..a778cd413b 100644
--- a/django/db/models/aggregates.py
+++ b/django/db/models/aggregates.py
@@ -65,7 +65,14 @@ class Aggregate(Func):
         c.filter = c.filter and c.filter.resolve_expression(
             query, allow_joins, reuse, summarize
         )
-        if not summarize:
+        if summarize:
+            # Summarized aggregates cannot refer to summarized aggregates.
+            for ref in c.get_refs():
+                if query.annotations[ref].is_summary:
+                    raise FieldError(
+                        f"Cannot compute {c.name}('{ref}'): '{ref}' is an aggregate"
+                    )
+        elif not self.is_summary:
             # Call Aggregate.get_source_expressions() to avoid
             # returning self.filter and including that in this loop.
             expressions = super(Aggregate, c).get_source_expressions()
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 252e5e9fcc..c4b435df2d 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -400,7 +400,10 @@ class Query(BaseExpression):
         """
         if not aggregate_exprs:
             return {}
-        aggregates = {}
+        # Store annotation mask prior to temporarily adding aggregations for
+        # resolving purpose to facilitate their subsequent removal.
+        replacements = {}
+        annotation_select_mask = self.annotation_select_mask
         for alias, aggregate_expr in aggregate_exprs.items():
             self.check_alias(alias)
             aggregate = aggregate_expr.resolve_expression(
@@ -408,7 +411,16 @@ class Query(BaseExpression):
             )
             if not aggregate.contains_aggregate:
                 raise TypeError("%s is not an aggregate expression" % alias)
-            aggregates[alias] = aggregate
+            # Temporarily add aggregate to annotations to allow remaining
+            # members of `aggregates` to resolve against each others.
+            self.append_annotation_mask([alias])
+            aggregate = aggregate.replace_expressions(replacements)
+            self.annotations[alias] = aggregate
+            replacements[Ref(alias, aggregate)] = aggregate
+        # Stash resolved aggregates now that they have been allowed to resolve
+        # against each other.
+        aggregates = {alias: self.annotations.pop(alias) for alias in aggregate_exprs}
+        self.set_annotation_mask(annotation_select_mask)
         # Existing usage of aggregation can be determined by the presence of
         # selected aggregates but also by filters against aliased aggregates.
         _, having, qualify = self.where.split_having_qualify()