Fixed #22977 -- Added check for clash between model manager and model field's related_name.

New check added on model related fields to check if the `related_name` conflicts with the respective model's manager name.

With thanks to kswiat, loic, felixxm and russellm

django/db/models/fields/related.py

@@ -581,6 +581,7 @@ class ForeignObject(RelatedField):
             *super().check(**kwargs),
             *self._check_to_fields_exist(),
             *self._check_unique_target(),
+            *self._check_conflict_with_managers(),
         ]
 
     def _check_to_fields_exist(self):
@@ -679,6 +680,28 @@ class ForeignObject(RelatedField):
                 ]
         return []
 
+    def _check_conflict_with_managers(self):
+        errors = []
+        for manager in self.opts.managers:
+            for rel_objs in self.model._meta.related_objects:
+                manager_name = manager.name
+                related_object_name = rel_objs.name
+                if manager_name == related_object_name:
+                    field_name = f"{self.model._meta.object_name}.{self.name}"
+                    errors.append(
+                        checks.Error(
+                            f"Related name for '{field_name}' clashes with "
+                            f"manager: '{related_object_name}' name.",
+                            hint=(
+                                "Rename manager name or related_name "
+                                "in conflicted field"
+                            ),
+                            obj=self,
+                            id="fields.E341",
+                        )
+                    )
+        return errors
+
     def deconstruct(self):
         name, path, args, kwargs = super().deconstruct()
         kwargs["on_delete"] = self.remote_field.on_delete

docs/ref/checks.txt

@@ -327,6 +327,8 @@ Related fields
 * **fields.E339**: ``<model>.<field name>`` is not a foreign key to ``<model>``.
 * **fields.E340**: The field's intermediary table ``<table name>`` clashes with
   the table name of ``<model>``/``<model>.<field name>``.
+* **fields.E341**: ``<model>``.``related_name`` must be different than the
+  ``<model>``'s manager name.
 * **fields.W340**: ``null`` has no effect on ``ManyToManyField``.
 * **fields.W341**: ``ManyToManyField`` does not support ``validators``.
 * **fields.W342**: Setting ``unique=True`` on a ``ForeignKey`` has the same

tests/invalid_models_tests/test_relative_fields.py

@@ -1407,6 +1407,29 @@ class ExplicitRelatedQueryNameClashTests(SimpleTestCase):
         )
 
 
+@isolate_apps("invalid_models_tests")
+class RelatedQueryNameClashWithManagerTests(SimpleTestCase):
+    def test_clash_between_related_query_name_and_manager(self):
+        class Author(models.Model):
+            authors = models.Manager()
+            mentor = models.ForeignKey(
+                "self", related_name="authors", on_delete=models.CASCADE
+            )
+
+        self.assertEqual(
+            Author.check(),
+            [
+                Error(
+                    "Related name for 'Author.mentor' clashes with manager: "
+                    "'authors' name.",
+                    hint="Rename manager name or related_name in conflicted field",
+                    obj=Author._meta.get_field("mentor"),
+                    id="fields.E341",
+                )
+            ],
+        )
+
+
 @isolate_apps("invalid_models_tests")
 class SelfReferentialM2MClashTests(SimpleTestCase):
     def test_clash_between_accessors(self):