Fixed #25417 -- Added a field check for invalid default values.

docs/ref/checks.txt

@@ -140,6 +140,7 @@ Fields
   human readable name)`` tuples.
 * **fields.E006**: ``db_index`` must be ``None``, ``True`` or ``False``.
 * **fields.E007**: Primary keys must not have ``null=True``.
+* **fields.E008**: Invalid ``default`` value.
 * **fields.E100**: ``AutoField``\s must set primary_key=True.
 * **fields.E110**: ``BooleanField``\s do not accept null values.
 * **fields.E120**: ``CharField``\s must define a ``max_length`` attribute.

docs/releases/1.9.txt

@@ -512,6 +512,9 @@ Models
 
 * ``connection.queries`` shows queries with substituted parameters on SQLite.
 
+* Added a new model field check that makes sure
+  :attr:`~django.db.models.Field.default` is a valid value.
+
 CSRF
 ^^^^