[5.0.x] Fixed #35373 -- Fixed a crash when indexing a generated field on SQLite.

Generated fields have to be excluded from the INSERT query against the remade
table including the index.

Thanks Moshe Dicker for the report, David Sanders and Mariusz Felisiak for the
review.

Backport of d048f0d311cc9cb9578d687968f2d24a0a9efddb from main.

django/db/backends/sqlite3/schema.py

@@ -150,6 +150,9 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
             body.pop(old_field.name, None)
             mapping.pop(old_field.column, None)
             body[new_field.name] = new_field
+            rename_mapping[old_field.name] = new_field.name
+            if new_field.generated:
+                continue
             if old_field.null and not new_field.null:
                 if new_field.db_default is NOT_PROVIDED:
                     default = self.prepare_default(self.effective_default(new_field))
@@ -162,7 +165,6 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
                 mapping[new_field.column] = case_sql
             else:
                 mapping[new_field.column] = self.quote_name(old_field.column)
-            rename_mapping[old_field.name] = new_field.name
         # Remove any deleted fields
         if delete_field:
             del body[delete_field.name]

docs/releases/5.0.5.txt

@@ -16,3 +16,7 @@ Bugfixes
 * Fixed a compatibility issue encountered in Python 3.11.9+ and 3.12.3+ when
   validating email max line lengths with content decoded using the
   ``surrogateescape`` error handling scheme (:ticket:`35361`).
+
+* Fixed a bug in Django 5.0 that caused a crash when applying migrations
+  including alterations to ``GeneratedField`` such as setting ``db_index=True``
+  on SQLite (:ticket:`35373`).

tests/schema/tests.py

@@ -934,6 +934,39 @@ class SchemaTests(TransactionTestCase):
         self.assertEqual(obj.generated, "%%foo")
         self.assertIs(obj.contains_foo, True)
 
+    @isolate_apps("schema")
+    @skipUnlessDBFeature("supports_stored_generated_columns")
+    def test_alter_generated_field(self):
+        class GeneratedFieldIndexedModel(Model):
+            number = IntegerField(default=1)
+            generated = GeneratedField(
+                expression=F("number"),
+                db_persist=True,
+                output_field=IntegerField(),
+            )
+
+            class Meta:
+                app_label = "schema"
+
+        with connection.schema_editor() as editor:
+            editor.create_model(GeneratedFieldIndexedModel)
+
+        old_field = GeneratedFieldIndexedModel._meta.get_field("generated")
+        new_field = GeneratedField(
+            expression=F("number"),
+            db_persist=True,
+            db_index=True,
+            output_field=IntegerField(),
+        )
+        new_field.contribute_to_class(GeneratedFieldIndexedModel, "generated")
+
+        with connection.schema_editor() as editor:
+            editor.alter_field(GeneratedFieldIndexedModel, old_field, new_field)
+
+        self.assertIn(
+            "generated", self.get_indexes(GeneratedFieldIndexedModel._meta.db_table)
+        )
+
     @isolate_apps("schema")
     def test_add_auto_field(self):
         class AddAutoFieldModel(Model):