Fixed #22064 -- Add check for related_name

Validates that related_name is a valid Python id or ends with a '+' and
it's not a keyword. Without a check it passed silently leading to
unpredictable problems.

Thanks Konrad Świat for the initial work.

1 files changed, 2 insertions, 0 deletions

diff --git a/docs/ref/checks.txt b/docs/ref/checks.txt
index aa3f61117c..841c8f4c48 100644
--- a/docs/ref/checks.txt
+++ b/docs/ref/checks.txt
@@ -117,6 +117,8 @@ Related Fields
   ``<field name>``.
 * **fields.E305**: Field name ``<field name>`` clashes with reverse query name
   for ``<field name>``.
+* **fields.E306**: Related name must be a valid Python identifier or end with
+  a ``'+'``.
 * **fields.E310**: None of the fields ``<field1>``, ``<field2>``, ... on model
   ``<model>`` have a ``unique=True`` constraint.
 * **fields.E311**: ``<model>`` must set ``unique=True`` because it is