[4.0.x] Fixed #33018 -- Fixed annotations with empty queryset.

Thanks Simon Charette for the review and implementation idea.

Backport of dd1fa3a31b4680c0d3712e6ae122b878138580c7 from main

3 files changed, 15 insertions, 3 deletions

diff --git a/django/db/models/expressions.py b/django/db/models/expressions.py
index 100da26ee6..a3317bc28c 100644
--- a/django/db/models/expressions.py
+++ b/django/db/models/expressions.py
@@ -702,7 +702,13 @@ class Func(SQLiteNumericMixin, Expression):
         sql_parts = []
         params = []
         for arg in self.source_expressions:
-            arg_sql, arg_params = compiler.compile(arg)
+            try:
+                arg_sql, arg_params = compiler.compile(arg)
+            except EmptyResultSet:
+                empty_result_set_value = getattr(arg, 'empty_result_set_value', NotImplemented)
+                if empty_result_set_value is NotImplemented:
+                    raise
+                arg_sql, arg_params = compiler.compile(Value(empty_result_set_value))
             sql_parts.append(arg_sql)
             params.extend(arg_params)
         data = {**self.extra, **extra_context}
@@ -1114,6 +1120,7 @@ class Subquery(BaseExpression, Combinable):
     """
     template = '(%(subquery)s)'
     contains_aggregate = False
+    empty_result_set_value = None
 
     def __init__(self, queryset, output_field=None, **extra):
         # Allow the usage of both QuerySet and sql.Query objects.
diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index 97288c83d7..d1009847e7 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -266,8 +266,12 @@ class SQLCompiler:
             try:
                 sql, params = self.compile(col)
             except EmptyResultSet:
-                # Select a predicate that's always False.
-                sql, params = '0', ()
+                empty_result_set_value = getattr(col, 'empty_result_set_value', NotImplemented)
+                if empty_result_set_value is NotImplemented:
+                    # Select a predicate that's always False.
+                    sql, params = '0', ()
+                else:
+                    sql, params = self.compile(Value(empty_result_set_value))
             else:
                 sql, params = col.select_format(self, sql, params)
             ret.append((col, (sql, params), alias))
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index d1c0c333f5..6436b25bae 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -143,6 +143,7 @@ class Query(BaseExpression):
     """A single SQL query."""
 
     alias_prefix = 'T'
+    empty_result_set_value = None
     subq_aliases = frozenset([alias_prefix])
 
     compiler = 'SQLCompiler'