Linter and formatter considers unrecognized file extension as Python files

[dhruvmanila]

Linter:

❯ ruff check --extend-select=Q biome.json
biome.json:1:2: Q000 [*] Double quotes found but single quotes preferred
  |
1 | {"$schema": "https://biomejs.dev/schemas/1.8.2/schema.json"}
  |  ^^^^^^^^^ Q000
  |
  = help: Replace double quotes with single quotes

biome.json:1:13: Q000 [*] Double quotes found but single quotes preferred
  |
1 | {"$schema": "https://biomejs.dev/schemas/1.8.2/schema.json"}
  |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Q000
  |
  = help: Replace double quotes with single quotes

Found 2 errors.
[*] 2 fixable with the `--fix` option.

Formatter:

❯ ruff format biome.json 
1 file reformatted

The root cause of this is that PySourceType::from_extension falls back to Python source type if the extension isn't recognized. But, we have the --extension flag to allow users to map any file extension to a Python file so we should use an Option<PySourceType> return type instead.

[samamorgan]

Is there an intermediate workaround for this?

[dhruvmanila]

@samamorgan Can you describe your workflow where you're facing this issue? Is it in an editor context? If so, are you using ruff-lsp or the new native server (ruff server)? Are you facing this issue via the command-line?

[AlexWaygood]

Strictly speaking, I think this behaviour might be... correct? If you pass a .json file directly to the Python interpreter and ask it to parse it as Python, the interpreter will happily do so, so it makes sense to me that Ruff would do the same if we passed it a .json file directly:

~/dev/experiment % cat script.json
print("Hello, world!")
~/dev/experiment % python script.json
Hello, world!

Although it's obviously not very common for people to save their Python scripts with .json extensions, it's not uncommon for people to save single-file scripts without any extension at all. E.g. here's a whole folder of them in a pretty popular project: https://github.com/asottile/reorder-python-imports/tree/main/testing

[charliermarsh]

I think this is correct (or at least intentional). If you pass a file directly to Ruff, we will always try to analyze it. You could probably add *.json to extend-exclude and then run with --force-exclude if you don't want it.

[samamorgan]

@samamorgan Can you describe your workflow where you're facing this issue? Is it in an editor context? If so, are you using ruff-lsp or the new native server (ruff server)? Are you facing this issue via the command-line?

I'm trying to update my project from ruff 0.2.2 -> 0.5.1 and have added a pre-commit hook to run ruff format. I hadn't fully thought it through, and needed to add a files pattern for pre-commit, since it's running the hook against all committed files.

My pattern that seems to do the trick: "\\.(py|pyi|ipynb)$"

[charliermarsh]

I think pre-commit should only be passing Python files? You can also set types_or: [ python, pyi, jupyter ]

[dhruvmanila]

Pre-commit docs reference: https://pre-commit.com/#filtering-files-with-types

Yeah, I think this behavior makes sense. I'll close this issue.