[5.0.x] Fixed #34944 -- Made GeneratedField.output_field required.

Regression in f333e3513e.

Backport of 5875f03ce6 from main

docs/ref/models/fields.txt

@@ -1243,7 +1243,7 @@ when :attr:`~django.forms.Field.localize` is ``False`` or
 
 .. versionadded:: 5.0
 
-.. class:: GeneratedField(expression, db_persist=None, output_field=None, **kwargs)
+.. class:: GeneratedField(expression, output_field, db_persist=None, **kwargs)
 
 A field that is always computed based on other fields in the model. This field
 is managed and updated by the database itself. Uses the ``GENERATED ALWAYS``
@@ -1265,6 +1265,10 @@ materialized view.
     the model (in the same database table). Generated fields cannot reference
     other generated fields. Database backends can impose further restrictions.
 
+.. attribute:: GeneratedField.output_field
+
+    A model field instance to define the field's data type.
+
 .. attribute:: GeneratedField.db_persist
 
     Determines if the database column should occupy storage as if it were a
@@ -1274,12 +1278,6 @@ materialized view.
     PostgreSQL only supports persisted columns. Oracle only supports virtual
     columns.
 
-.. attribute:: GeneratedField.output_field
-
-    An optional model field instance to define the field's data type. This can
-    be used to customize attributes like the field's collation. By default, the
-    output field is derived from ``expression``.
-
 .. admonition:: Refresh the data
 
     Since the database always computed the value, the object must be reloaded

docs/releases/5.0.txt

@@ -142,7 +142,11 @@ to create a field that is always computed from other fields. For example::
 
     class Square(models.Model):
         side = models.IntegerField()
-        area = models.GeneratedField(expression=F("side") * F("side"), db_persist=True)
+        area = models.GeneratedField(
+            expression=F("side") * F("side"),
+            output_field=models.BigIntegerField(),
+            db_persist=True,
+        )
 
 More options for declaring field choices
 ----------------------------------------