AttributeError: 'FuncDef' object has no attribute 'is_trivial_self'

[redb0]

Python code:

from typing import Any

from rest_framework.response import Response
from rest_framework.viewsets import ModelViewSet


class UserView(ModelViewSet):
    """Create, List, Update user model. Available for SuperAdmin only."""

    def list(
        self,
        *args: Any,
        **kwargs: Any,
    ) -> Response:
        return Response({"a": 1})

Returns an error when checking AttributeError: 'FuncDef' object has no attribute 'is_trivial_self'

Diagnostic Data

• Python version 3.12.10

uv pip list
Package                       Version
----------------------------- -----------------
amqp                          5.3.1
argcomplete                   3.6.2
asgiref                       3.8.1
async-timeout                 4.0.3
attrs                         25.3.0
autobahn                      24.4.2
automat                       25.4.16
billiard                      4.2.1
celery                        5.4.0
certifi                       2023.11.17
cffi                          1.17.1
channels                      4.0.0
channels-redis                4.1.0
charset-normalizer            3.4.2
click                         8.1.7
click-didyoumean              0.3.1
click-plugins                 1.1.1
click-repl                    0.3.0
colorama                      0.4.6
commitizen                    4.8.2
constantly                    23.10.4
coreapi                       2.3.3
coreschema                    0.0.4
cron-descriptor               1.4.3
croniter                      3.0.3
cryptography                  45.0.3
daphne                        4.0.0
decli                         0.6.3
django                        4.2.7
django-aesfield               4.0.0
django-celery-beat            2.6.0
django-cors-headers           4.3.1
django-filter                 24.3
django-stubs                  1.9.0
django-stubs-ext              5.2.0
django-timezone-field         7.1
djangorestframework           3.14.0
djangorestframework-simplejwt 5.3.0
djangorestframework-stubs     1.4.0
drf-extra-fields              3.7.0
drf-yasg                      1.21.7
et-xmlfile                    2.0.0
filetype                      1.2.0
flake8                        7.2.0
grpcio                        1.59.3
grpcio-tools                  1.59.3
gunicorn                      21.2.0
hyperlink                     21.0.0
idna                          3.10
incremental                   24.7.2
inflection                    0.5.1
iniconfig                     2.1.0
itypes                        1.2.0
jinja2                        3.1.6
kombu                         5.5.4
loguru                        0.7.2
m2secret-py3                  1.3
markupsafe                    3.0.2
mccabe                        0.7.0
msgpack                       1.1.0
mypy                          1.16.0
mypy-extensions               1.1.0
numpy                         1.26.2
openpyxl                      3.1.5
orjson                        3.9.14
packaging                     25.0
pandas                        2.1.3
pandas-stubs                  2.3.0.250703
pathspec                      0.12.1
pluggy                        1.6.0
prompt-toolkit                3.0.51
protobuf                      4.25.1
psycopg2-binary               2.9.9
pyasn1                        0.6.1
pyasn1-modules                0.4.2
pycodestyle                   2.13.0
pycparser                     2.22
pyflakes                      3.3.2
pygments                      2.19.1
pyjwt                         2.10.1
pyopenssl                     25.1.0
pytest                        8.4.0
python-crontab                3.2.0
python-dateutil               2.9.0.post0
python-dotenv                 1.0.0
pytz                          2025.2
pyyaml                        6.0.2
questionary                   2.1.0
redis                         5.0.1
requests                      2.31.0
ruff                          0.11.12
service-identity              24.2.0
setuptools                    80.9.0
six                           1.17.0
sqlparse                      0.5.3
termcolor                     2.5.0
toml                          0.10.2
tomlkit                       0.13.3
twisted                       24.11.0
txaio                         23.1.1
types-grpcio                  1.0.0.20250603
types-protobuf                4.25.0.20240417
types-pytz                    2025.2.0.20250516
types-pyyaml                  6.0.12.20250516
types-requests                2.32.0.20250602
typing-extensions             4.14.0
tzdata                        2025.2
uritemplate                   4.2.0
urllib3                       2.4.0
vine                          5.1.0
wcwidth                       0.2.13
wemake-python-styleguide      1.1.0
xlsxwriter                    3.1.9
zope-interface                7.2

Behaviour

Expected Behavior

Actual Behavior

Reproduction Steps:

Logs:

2025-09-03 07:50:36.389 [info] [Trace - 7:50:36 AM] Received notification 'textDocument/publishDiagnostics'.
2025-09-03 07:50:36.924 [info] [Trace - 7:50:36 AM] Sending notification 'textDocument/didChange'.
2025-09-03 07:50:37.063 [info] [Trace - 7:50:37 AM] Sending notification 'textDocument/didChange'.
2025-09-03 07:50:37.213 [info] [Trace - 7:50:37 AM] Sending notification 'textDocument/didChange'.
2025-09-03 07:50:37.560 [info] [Trace - 7:50:37 AM] Sending notification 'textDocument/didSave'.
2025-09-03 07:50:37.564 [info] [Trace - 7:50:37 AM] Received notification 'window/logMessage'.
2025-09-03 07:50:37.565 [info] /home/name/projects/oss-core/osscore/.venv/bin/python3 -m mypy --no-color-output --no-error-summary --show-absolute-path --show-column-numbers --show-error-codes --no-pretty --config-file=./pyproject.toml --show-error-end /home/name/projects/oss-core/osscore/t.py
2025-09-03 07:50:37.565 [info] [Trace - 7:50:37 AM] Received notification 'window/logMessage'.
2025-09-03 07:50:37.566 [info] CWD Server: /home/name/projects/oss-core/osscore
2025-09-03 07:50:39.195 [info] [Trace - 7:50:39 AM] Received notification 'window/logMessage'.
2025-09-03 07:50:39.195 [info] /home/name/projects/oss-core/osscore/.venv/lib/python3.12/site-packages/drf_yasg/__init__.py:2: UserWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html. The pkg_resources package is slated for removal as early as 2025-11-30. Refrain from using this package or pin to Setuptools<81.
  from pkg_resources import DistributionNotFound, get_distribution
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/__main__.py", line 37, in <module>
    console_entry()
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/__main__.py", line 15, in console_entry
    main()
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/main.py", line 119, in main
    res, messages, blockers = run_build(sources, options, fscache, t0, stdout, stderr)
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/main.py", line 203, in run_build
    res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/build.py", line 191, in build
    result = _build(
             ^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/build.py", line 267, in _build
    graph = dispatch(sources, manager, stdout)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/build.py", line 2937, in dispatch
    process_graph(graph, manager)
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/build.py", line 3328, in process_graph
    process_fresh_modules(graph, prev_scc, manager)
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/build.py", line 3406, in process_fresh_modules
    graph[id].load_tree()
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/build.py", line 2096, in load_tree
    self.tree = MypyFile.deserialize(data)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/nodes.py", line 389, in deserialize
    tree.names = SymbolTable.deserialize(data["names"])
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/nodes.py", line 4039, in deserialize
    st[key] = SymbolTableNode.deserialize(value)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/nodes.py", line 3980, in deserialize
    node = SymbolNode.deserialize(data["node"])
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/nodes.py", line 250, in deserialize
    return method(data)
           ^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/nodes.py", line 3401, in deserialize
    names = SymbolTable.deserialize(data["names"])
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/nodes.py", line 4039, in deserialize
    st[key] = SymbolTableNode.deserialize(value)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/nodes.py", line 3980, in deserialize
    node = SymbolNode.deserialize(data["node"])
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/nodes.py", line 250, in deserialize
    return method(data)
           ^^^^^^^^^^^^
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/nodes.py", line 853, in deserialize
    set_flags(ret, data["flags"])
  File "/home/name/.vscode/extensions/ms-python.mypy-type-checker-2025.2.0/bundled/libs/mypy/nodes.py", line 4099, in set_flags
    setattr(node, name, True)
AttributeError: 'FuncDef' object has no attribute 'is_trivial_self'

2025-09-03 07:50:39.195 [info] [Trace - 7:50:39 AM] Received notification 'window/logMessage'.
2025-09-03 07:50:39.195 [info] file:///home/vvoronov/projects/oss-core/osscore/t.py :

2025-09-03 07:50:39.195 [info] [Trace - 7:50:39 AM] Received notification 'textDocument/publishDiagnostics'.

[rchiodo]

Eleanor Boyd (@eleanorjboyd) this looks like a bug in mypy, not pylance.

[rchiodo]

I don't have permissions to transfer back