Can create model instance with conflicting args and kwargs value for the same field

[Peter Zsoldos]

Discovered while working on #18586

To reproduce it, add the following test (it's using tests.basic.models.Article)

    from django.utils import six
    def test_cannot_specify_same_field_with_args_and_kwargs_too(self):
        six.assertRaisesRegex(
            self,
            TypeError,
            "__init__() got multiple values for argument 'headline'",
            Article,
            None, # id
            'args based headline',
            headline='kwargs based headline',
            pub_date=datetime(2005, 7, 31),
        )

[Tim Graham]

For what it's worth, I didn't realize there was any attempt to support positional arguments in model instantiation (although it is tested, is it documented anywhere?). May not be worth fixing, in my opinion.

[Baptiste Mispelon]

Hi,

From what I understand, *args instanciation is there for performance reasons (see [1]).

I'll accept this ticket on the basis that it'd be nice to fix it but only if it doesn't impact performance negatively.

Thanks.

[1] ​https://github.com/django/django/blob/908c67e719a54b8b612cb7df732126f42350f3fa/django/db/models/base.py#L418-L421