TypeError: Flask.url_for() got multiple values for argument 'self'

[sda97ghb]

Official documentation doesn't mention any preconditions for values argument, but self=1 raises an exception.

Can be replicated with the following test case:

from unittest import TestCase

from flask import Flask, url_for


class UrlForTests(TestCase):
    def setUp(self) -> None:
        self.app = Flask(__name__)

    def test_with_self_argument(self) -> None:
        with (
            self.app.app_context(),
            self.assertRaisesRegex(
                TypeError, "got multiple values for argument 'self'"
            ),
        ):
            url_for("doesnotmatter", self=1)

Traceback example:

Traceback (most recent call last):
  File "/home/dmitry/git/github.com/minetest/contentdb/tests.py", line 6, in <module>
    url_for("doesnotmatter", self=1)
  File "/home/dmitry/.cache/pypoetry/virtualenvs/contentdb-MK2UWkId-py3.10/lib/python3.10/site-packages/flask/helpers.py", line 256, in url_for
    return current_app.url_for(
TypeError: Flask.url_for() got multiple values for argument 'self'

The expected behavior is the returned URL has query string like '?self=1'.

Environment:

• Python version: 3.10.6
• Flask version: 2.3.3

[ThiefMaster]

Probably self of that method should be made positional-only (unless we still support a Python version that does not support positional-only arguments). As a workaround we could possibly rename it to something like ___self that is almost certainly never used in a real URL param...

[davidism]

Let's get this into 3.0 and use a position only arg.