Mypy linting not working for mypy 0.990 - no issues found

[MetRonnie]

Type: Bug

Behaviour

Expected vs. Actual

Expected: mypy errors are found.

Actual: mypy reports no errors.

Steps to reproduce:

1. Introduce a deliberate type error
2. Run mypy <filepath> on the command line to confirm that the problem is genuine
3. Inspect the Python Output panel to see that you get nothing:

   ##########Linting Output - mypy##########
   
   Success: no issues found in 1 source file
   

Mypy version: mypy 0.990 (compiled: yes)

Edit: I have tested and linting works for mypy 0.981

Diagnostic data

• Python version (& distribution if applicable, e.g. Anaconda): 3.10.6
• Type of virtual environment used (e.g. conda, venv, virtualenv, etc.): Conda
• Value of the python.languageServer setting: Pylance

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

> /opt/conda/bin/conda run -n env_name --no-capture-output python /net/~/.vscode/extensions/ms-python.python-2022.16.1/pythonFiles/get_output_via_markers.py /net/~/.vscode/extensions/ms-python.python-2022.16.1/pythonFiles/linter.py -m mypy --ignore-missing-imports --follow-imports=silent --show-column-numbers --show-error-codes --explicit-package-bases --namespace-packages ./path/to/file.py
cwd: .
##########Linting Output - mypy##########

Success: no issues found in 1 source file

User Settings

condaPath: "<placeholder>"

languageServer: "Pylance"

linting
• mypyArgs: "<placeholder>"
• mypyEnabled: true

formatting
• autopep8Args: "<placeholder>"

testing
• pytestArgs: "<placeholder>"
• pytestEnabled: true

Extension version: 2022.16.1
VS Code version: Code 1.72.2 (d045a5eda657f4d7b676dedbfa7aab8207f8a075, 2022-10-12T22:16:26.920Z)
OS version: Linux x64 3.10.0-1160.76.1.el7.x86_64
Modes:
Sandboxed: No

System Info

Item	Value
CPUs	Intel(R) Xeon(R) CPU E5-2690 v4 @ 2.60GHz (4 x 2599)
GPU Status	2d_canvas: unavailable_software canvas_oop_rasterization: disabled_off direct_rendering_display_compositor: disabled_off_ok gpu_compositing: disabled_software multiple_raster_threads: enabled_on opengl: disabled_off rasterization: disabled_software raw_draw: disabled_off_ok skia_renderer: enabled_on video_decode: disabled_software video_encode: disabled_software vulkan: disabled_off webgl: unavailable_software webgl2: unavailable_software webgpu: disabled_off
Load (avg)	1, 3, 3
Memory (System)	7.62GB (1.80GB free)
Process Argv	--unity-launch --crash-reporter-id 4cb3165e-6680-471f-992f-0c1e623756f7
Screen Reader	no
VM	100%
DESKTOP_SESSION	1-gnome
XDG_CURRENT_DESKTOP	GNOME
XDG_SESSION_DESKTOP	1-gnome
XDG_SESSION_TYPE	x11

[karthiknadig]

There should be a linter command arguments in the Output > python logs. can you run that in the terminal? it should be running linter.py with few arguments.

[MetRonnie]

> /opt/conda/bin/conda run -n env_name --no-capture-output python
    /net/~/.vscode/extensions/ms-python.python-2022.16.1/pythonFiles/get_output_via_markers.py
    /net/~/.vscode/extensions/ms-python.python-2022.16.1/pythonFiles/linter.py -m mypy --ignore-missing-imports
    --follow-imports=silent --show-column-numbers --show-error-codes --explicit-package-bases
    --namespace-packages ./path/to/file.py
cwd: .
##########Linting Output - mypy##########

Success: no issues found in 1 source file

• Not sure why some of the paths show up starting with /net/~/, probably a quirk to do with NFS, but copying and pasting the command and removing the /net/ works for me and shows the mypy errors
• The mypy options come from my settings (python.linting.mypyArgs). Removing them didn't help.

[najtin]

Same issue here, without the /net/ thing. The paths look fine.

• Python version (& distribution if applicable, e.g. Anaconda): 3.10.6, apt ubuntu
• Type of virtual environment used (e.g. conda, venv, virtualenv, etc.): poetry (i guess they use venv?)
• Value of the python.languageServer setting: Default
• Mypy: 0.990 (can confirm, works with 0.981)

I use poetry and installed flake8 and mypy in a local venv using poetry. Flake works fine but mypy does not report any issues. To be clear it does report something: Success: no issues found in 1 source file But it should instead report an issue with the code.

Here is the code i want to check:

def a() -> str:
    1

Clearly, mypy should complain about the missing return statement.
Here is the output of the Output tab:

LSP Notebooks experiment is disabled -- not using Pylance
LSP Notebooks interactive window support is disabled -- not in LSP Notebooks experiment
> conda info --json
Python interpreter path: ./.venv/bin/python
> ~/.conda/bin/conda info --json
> . ./.venv/bin/activate && echo 'e8b39361-0157-4923-80e1-22d70d46dee6' && python ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/printEnvVariables.py
> ~/.julia/conda/3/bin/conda info --json
> ./.venv/bin/python ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/get_output_via_markers.py ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/interpreterInfo.py
> /bin/python ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/get_output_via_markers.py ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/interpreterInfo.py
> /usr/bin/python ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/get_output_via_markers.py ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/interpreterInfo.py
> ~/.julia/conda/3/bin/python ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/get_output_via_markers.py ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/interpreterInfo.py
Starting Jedi language server for rootsnakes.
> ./.venv/bin/python ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/linter.py -m mypy --follow-imports=silent --ignore-missing-imports --show-column-numbers --no-pretty ./rootsnakes/app.py
cwd: .
> ./.venv/bin/python ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/linter.py -m flake8 ./rootsnakes/app.py
cwd: .
##########Linting Output - mypy##########

Success: no issues found in 1 source file

##########Linting Output - flake8##########

When we run the exact same command in the terminal window (with venv activated) or in a fresh shell without activating the venv we get the expected result:

./.venv/bin/python ~/.vscode-oss/extensions/ms-python.python-2022.16.1-universal/pythonFiles/linter.py -m mypy --follow-imports=silent --ignore-missing-imports --show-column-numbers --no-pretty ./lol.py
lol.py:1:1: error: Missing return statement  [return]
Found 1 error in 1 file (checked 1 source file)

Extension version: 2022.16.1
VSCodium version: VSCodium 1.72.2 (378660f7dd07287aa34acf90e8fec157425c1ac8, 2022-10-16T23:03:19.989Z)
OS version: Linux x64 5.15.0-52-generic snap
Modes:
Sandboxed: No

System Info

Item	Value
CPUs	-
GPU Status	-
Load (avg)	1, 0, 0
Memory (System)	15.19GB (3.28GB free)
Process Argv	--ms-enable-electron-run-as-node --no-sandbox --unity-launch
Screen Reader	no
VM	0%
DESKTOP_SESSION	mate
XDG_CURRENT_DESKTOP	MATE
XDG_SESSION_DESKTOP	mate
XDG_SESSION_TYPE	x11

[karthiknadig]

@najtin For flake8 can you try using the flake8 extension from marketplace https://marketplace.visualstudio.com/items?itemName=ms-python.flake8

[najtin]

I think this is related to the issue above (for completeness python/mypy#14042 )

[najtin]

@najtin For flake8 can you try using the flake8 extension from marketplace https://marketplace.visualstudio.com/items?itemName=ms-python.flake8

No, flake8 works as expected. This issue does also occur when flake8 is not installed.

[karthiknadig]

The difference between mypy 0.982 vs 0.990 is that with 0.990 mypy shows error code.

mypy == 0.982

(.venv) C:\GIT\repro\mypytest>python "C:\Users\kanadig\.vscode\extensions\ms-python.python-2022.19.13131832\pythonFiles\linter.py" -m mypy --follow-imports=silent --ignore-missing-imports --show-column-numbers --no-pretty simple.py
simple.py:1:10: error: Incompatible types in assignment (expression has type "str", variable has type "int")
Found 1 error in 1 file (checked 1 source file)

mypy == 0.990

(.venv) C:\GIT\repro\mypytest>python "C:\Users\kanadig\.vscode\extensions\ms-python.python-2022.19.13131832\pythonFiles\linter.py" -m mypy --follow-imports=silent --ignore-missing-imports --show-column-numbers --no-pretty simple.py
simple.py:1:10: error: Incompatible types in assignment (expression has type "str", variable has type "int")  [assignment]
Found 1 error in 1 file (checked 1 source file)

Even with that difference it seems to be working for me:

[karthiknadig]

Can you share the output from pip list?

[najtin]

While trying to recreate a minimal working example i found that for some reason it works if you add mypy through poetry add --dev mypy, but it does not work if you change the pyproject.toml by hand and run poetry install. You can also first add mypy through poetry (it works at that moment) and then delete the .venv folder, then run poetry install, resulting in no working linting.
I am really baffled and confused why this would make a difference.

In more detail

To reproduce case (poetry add --dev mypy) run the following:

poetry new example
poetry add --dev mypy
codium .
#mypy works

To reproduce case (poetry install) run the following:

poetry new example
poetry add --dev mypy
rm -r .venv .mypy_cache
poetry install
codium .
#mypy does not work

pyproject.toml:

[tool.poetry]
name = "example-manual"
version = "0.1.0"
description = ""
authors = ["Your Name <you@example.com>"]
readme = "README.md"
packages = [{include = "example_manual"}]

[tool.poetry.dependencies]
python = "^3.10"


[tool.poetry.group.dev.dependencies]
mypy = "^0.990"

[build-system]
requires = ["poetry-core"]
build-backend = "poetry.core.masonry.api"

Here is the pip list you requested case (poetry add --dev mypy) (mypy works):

Package           Version
----------------- -------
mypy              0.990
mypy-extensions   0.4.3
pip               22.3
setuptools        65.5.0
tomli             2.0.1
typing_extensions 4.4.0
wheel             0.37.1

case (poetry install) (mypy does not work)

Package           Version Editable project location
----------------- ------- --------------------------------------
example-manual    0.1.0   /home/work/Repositories/example_manual
mypy              0.990
mypy-extensions   0.4.3
pip               22.3
setuptools        65.5.0
tomli             2.0.1
typing_extensions 4.4.0
wheel             0.37.1

These results make me think that this issue should be tracked at mypy under python/mypy#14054 because it seems like the working folder has been added to the path, otherwise pip would not list the project as an installed package. Therefore the plugin here seems to work fine but mypy introduced breaking changes in 0.990, making it an issue with mypy.

[MetRonnie]

My pip list output:

Click to show

Package                        Version     Editable project location
------------------------------ ----------- --------------------------------------------------
aiofiles                       0.7.0
alabaster                      0.7.12
alembic                        1.8.1
aniso8601                      7.0.0
ansimarkup                     1.5.0
anyio                          3.6.1
argon2-cffi                    21.3.0
argon2-cffi-bindings           21.2.0
astor                          0.8.1
asttokens                      2.0.8
async-generator                1.10
async-timeout                  4.0.2
attrs                          22.1.0
autopep8                       1.7.0
Babel                          2.10.3
backcall                       0.2.0
bandit                         1.7.4
beautifulsoup4                 4.11.1
bleach                         5.0.1
certifi                        2022.9.24
certipy                        0.1.3
cffi                           1.15.1
charset-normalizer             2.1.1
colorama                       0.4.5
contourpy                      1.0.5
coverage                       6.5.0
cryptography                   38.0.1
cycler                         0.11.0
cylc-doc                       0.0.1       <HOME>/github/cylc-doc
cylc-flow                      8.1.0.dev0  <HOME>/github/cylc-flow-8.1
cylc-rose                      1.1.1       <HOME>/github/cylc-rose
cylc-sphinx-extensions         1.4.1       <HOME>/github/cylc-sphinx-extensions
cylc-uiserver                  1.2.0.dev0  <HOME>/github/cylc-uiserver
debugpy                        1.6.3
decorator                      5.1.1
defusedxml                     0.7.1
docutils                       0.17.1
empy                           3.3.4
entrypoints                    0.4
ERAlchemy                      1.2.10
execnet                        1.9.0
executing                      1.1.0
fastjsonschema                 2.16.2
flake8                         5.0.4
flake8-broken-line             0.6.0
flake8-bugbear                 22.9.23
flake8-builtins                1.5.3
flake8-comprehensions          3.10.0
flake8-debugger                4.1.2
flake8-mutable                 1.2.0
flake8-simplify                0.19.3
fonttools                      4.37.4
gitdb                          4.0.9
GitPython                      3.1.27
graphene                       2.1.9
graphene-tornado               2.6.1
graphql-core                   2.3.2
graphql-relay                  2.0.1
graphql-ws                     0.4.4
greenlet                       1.1.3
hieroglyph                     2.1.0
idna                           3.4
imagesize                      1.4.1
iniconfig                      1.1.1
ipython                        8.5.0
jedi                           0.18.1
Jinja2                         3.0.3
jsonschema                     4.16.0
jupyter-client                 7.3.1
jupyter-core                   4.11.1
jupyter-server                 1.19.1
jupyter-telemetry              0.1.0
jupyterhub                     3.0.0
jupyterlab-pygments            0.2.2
kiwisolver                     1.4.4
ldap3                          2.9.1
livereload                     2.6.3
Mako                           1.2.3
MarkupSafe                     2.1.1
matplotlib                     3.6.0
matplotlib-inline              0.1.6
mccabe                         0.7.0
memory-profiler                0.60.0
metomi-isodatetime             1!3.0.0     <HOME>/github/isodatetime
metomi-rose                    2.0.2.dev0  <HOME>/github/rose
mistune                        2.0.4
mypy                           0.990
mypy-extensions                0.4.3
nbclient                       0.6.8
nbconvert                      7.1.0
nbformat                       5.6.1
nest-asyncio                   1.5.6
numpy                          1.23.3
oauthlib                       3.2.1
packaging                      21.3
pamela                         1.0.0
pandas                         1.5.0
pandocfilters                  1.5.0
parso                          0.8.3
pbr                            5.10.0
pexpect                        4.8.0
pickleshare                    0.7.5
Pillow                         9.2.0
pip                            22.2.2
pluggy                         1.0.0
prometheus-client              0.14.1
promise                        2.3
prompt-toolkit                 3.0.31
protobuf                       4.21.7
psutil                         5.9.2
ptyprocess                     0.7.0
pure-eval                      0.2.2
py                             1.11.0
pyasn1                         0.4.8
pycodestyle                    2.9.1
pycparser                      2.21
pyenchant                      3.2.2
pyflakes                       2.5.0
Pygments                       2.13.0
pygraphviz                     1.10
Pympler                        1.0.1
pyOpenSSL                      22.1.0
pyparsing                      3.0.9
pyrsistent                     0.18.1
pytest                         7.1.3
pytest-asyncio                 0.19.0
pytest-cov                     4.0.0
pytest-env                     0.6.2
pytest-forked                  1.4.0
pytest-mock                    3.9.0
pytest-tornasync               0.6.0.post2
pytest-xdist                   2.5.0
python-dateutil                2.8.2
python-json-logger             2.0.4
pytoolconfig                   1.2.2
pytz                           2022.4
PyYAML                         6.0
pyzmq                          22.3.0
requests                       2.28.1
rope                           1.3.0
ruamel.yaml                    0.17.21
ruamel.yaml.clib               0.2.6
Rx                             1.6.1
Send2Trash                     1.8.0
setuptools                     65.4.1
six                            1.16.0
smmap                          5.0.0
snakeviz                       2.1.1
sniffio                        1.3.0
snowballstemmer                2.2.0
soupsieve                      2.3.2.post1
Sphinx                         5.2.3
sphinx-autobuild               2021.3.14
sphinx-rtd-theme               1.0.0
sphinxcontrib-applehelp        1.0.2
sphinxcontrib-devhelp          1.0.2
sphinxcontrib-htmlhelp         2.0.0
sphinxcontrib-httpdomain       1.8.0
sphinxcontrib-jsmath           1.0.1
sphinxcontrib-qthelp           1.0.3
sphinxcontrib-serializinghtml  1.1.5
sphinxcontrib-spelling         7.6.0
sphinxcontrib-svg2pdfconverter 1.2.0
SQLAlchemy                     1.4.41
sqlparse                       0.4.3
stack-data                     0.5.1
stevedore                      4.0.0
terminado                      0.16.0
testfixtures                   7.0.0
tinycss2                       1.1.1
toml                           0.10.2
tomli                          2.0.1
tornado                        6.2
traitlets                      5.4.0
types-aiofiles                 22.1.0
types-Jinja2                   2.11.9
types-MarkupSafe               1.1.10
types-pkg-resources            0.1.3
types-protobuf                 3.20.4
types-setuptools               65.4.0.0
types-six                      1.16.21
typing_extensions              4.3.0
urllib3                        1.26.12
urwid                          2.1.2
wcwidth                        0.2.5
webencodings                   0.5.1
websocket-client               1.4.1
Werkzeug                       0.12.2
wheel                          0.37.1

[karthiknadig]

Looks like this might be a mypy issue, closing this for now.

Track here: python/mypy#14054

[MetRonnie]

Can confirm working again with Mypy 0.991