Fixed #32263 -- Fixed squashmigrations result with RenameModel on a FK target.

django/db/migrations/operations/base.py

@@ -146,6 +146,9 @@ class Operation:
 
         return router.allow_migrate_model(connection_alias, model)
 
+    def reduce_related(self, operation, app_label):
+        return None
+
     def reduce(self, operation, app_label):
         """
         Return either a list of operations the actual operation should be

django/db/migrations/operations/models.py

@@ -134,6 +134,43 @@ class CreateModel(ModelOperation):
                 return True
         return False
 
+    def reduce_related(self, operation, app_label):
+        if isinstance(operation, RenameModel):
+            impacted_fields = [
+                (_, field)
+                for _, field in self.fields
+                if field.remote_field
+                and field.remote_field.model
+                == f"{app_label}.{operation.old_name_lower}"
+            ]
+            if len(impacted_fields) == 0:
+                return [self]
+
+            not_impacted_fields = [
+                (_, field)
+                for (_, field) in self.fields
+                if (_, field) not in impacted_fields
+            ]
+
+            fixed_fields = []
+
+            for _, impacted_field in impacted_fields:
+                name, path, args, kwargs = impacted_field.deconstruct()
+                kwargs["to"] = f"{app_label}.{operation.new_name_lower}"
+                impacted_field = impacted_field.__class__(*args, **kwargs)
+                fixed_fields.append((_, impacted_field))
+
+            return [
+                CreateModel(
+                    name=self.name,
+                    fields=not_impacted_fields + fixed_fields,
+                    options=self.options,
+                    bases=self.bases,
+                    managers=self.managers,
+                ),
+            ]
+        return super().reduce_related(operation, app_label)
+
     def reduce(self, operation, app_label):
         if (
             isinstance(operation, DeleteModel)

django/db/migrations/optimizer.py

@@ -46,6 +46,7 @@ class MigrationOptimizer:
             for j, other in enumerate(operations[i + 1 :]):
                 result = operation.reduce(other, app_label)
                 if isinstance(result, list):
+                    new_reduced_operations = []
                     in_between = operations[i + 1 : i + j + 1]
                     if right:
                         new_operations.extend(in_between)
@@ -59,8 +60,13 @@ class MigrationOptimizer:
                         # Otherwise keep trying.
                         new_operations.append(operation)
                         break
-                    new_operations.extend(operations[i + j + 2 :])
-                    return new_operations
+
+                    for _, op in enumerate(new_operations):
+                        new_reduced_operations.extend(
+                            op.reduce_related(other, app_label) or [op]
+                        )
+                    new_reduced_operations.extend(operations[i + j + 2 :])
+                    return new_reduced_operations
                 elif not result:
                     # Can't perform a right reduction.
                     right = False

tests/migrations/test_optimizer.py

@@ -649,6 +649,35 @@ class OptimizerTests(SimpleTestCase):
             ],
         )
 
+    def test_rename_model_referenced_by_fk(self):
+        self.assertOptimizesTo(
+            [
+                migrations.CreateModel("Author", []),
+                migrations.CreateModel(
+                    "Book",
+                    [
+                        (
+                            "author",
+                            models.ForeignKey("migrations.author", models.CASCADE),
+                        ),
+                    ],
+                ),
+                migrations.RenameModel("Author", "Person"),
+            ],
+            [
+                migrations.CreateModel("Person", []),
+                migrations.CreateModel(
+                    "Book",
+                    [
+                        (
+                            "author",
+                            models.ForeignKey("migrations.person", models.CASCADE),
+                        ),
+                    ],
+                ),
+            ],
+        )
+
     def test_create_model_alter_field(self):
         """
         AlterField should optimize into CreateModel.