Mypy linting errors should not be displayed if they are located in other Python files

[AWhetter]

Please note that this issue is based on a previous issue for the same problem: #9496
I've tried each version of the Python extension that was released after this original issue was fixed, and I see the error in each version.

Environment data

• VS Code version: 1.41.1
• Extension version (available under the Extensions sidebar): 2020.2.63072
• OS and version: Arch Linux
• Python version (& distribution if applicable, e.g. Anaconda): 3.8.1
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): venv
• Relevant/affected Python packages and their versions: mypy
• Jedi or Language Server? (i.e. what is "python.jediEnabled" set to; more info How to update the language server to the latest stable version #3977): jedi
• Value of the python.languageServer setting: Microsoft

Expected behaviour

The Python code editor only highlights errors in the file in question.

Actual behaviour

The Python code editor wrongly highlights unrelated errors found in other files that Mypy checked.

Steps to reproduce:

See #9496

I am testing with mixology, which can be cloned from here: https://github.com/sdispater/mixology
I view the files mixology/partial_solution.py, mixology/version_solver.py, and mixology/package_source.py. There may be more.

Logs

##########Linting Output - mypy##########
mixology/package.py:17:5: error: Type signature has too few arguments
Found 1 error in 1 file (checked 1 source file)

[kimadeline]

Hi @AWhetter 👋 Thank you for reaching out.

If you open the Python output channel (View→Output, change the drop-down the upper-right of the Output panel to Python) you'll see how mypy is being executed on package.py, something along the lines of path/to/python3 -m mypy --ignore-missing-imports --follow-imports=silent --show-column-numbers path/to/mixology/package.py.

When executing this command directly in the terminal the linting error is being reported, which means that it's not caused by the Python extension, but rather by an actual linting issue in mixology/package.py, or something in mypy.

[AWhetter]

Hi @kimadeline. Thanks for the response. Yes there is an error in the code. However the error is being reported in every file that imports it, not just in the file with the error.

To clarify my original issue, there's an error in mixology/package.py, as you mentioned, on line 17. When viewing mixology/partial_solution.py, mixology/version_solver.py, or mixology/package_source.py VSCode reports that same error on line 17 of each of those files, even though the error is in mixology/package.py.

To outline the example in #9496, an error is added to midi.py, but VSCode reports that error in redblue.py and circuits.py as well, on the line that has the same line number as the error in midi.py.

[kimadeline]

Thank you for the clarification, I can now reproduce the behaviour you're encountering 👍

Side note: this issue happens for versions of the extension predating #9496 (I reproduced it on 2019.10.44104), so it isn't a regression, I'll update the title accordingly.

Notes when fixing this issue

1. When parsing the output of running mypy on a file, we should exclude errors reported on other files:
   

2. Once step 1 is addressed, run mypy with filepaths relative to the workspace directory (fix(client/linters/mypy): call mypy incorrectly #5834 took a stab at it, however it introduced Regression: Mypy integration highlights errors from other files when editing a Python file #9496, probably because we should have fixed 1. first).