Linting only on changed lines of open files

[noelevans]

I just opened a PR for a Python linter, graylint. Its unique feature for Python is that it only flags issues on lines of a file if they are not yet under git source control. I work mostly on a very long-living project which has many lint items that would be flagged. I'm not interest in fixing the thousands of issues to potentially fix. I just want to see errors flagged in the code I am writing / editing today. Graylint is therefore great but on some files take 20+ seconds to process files - not an ideal user experience. Alternatively there is Ruff which on the same files runs < 0.1 seconds but does not support flagging modified / new lines only.

Then moving to other languages, the same feature would be of great use; only flagging lines of code that are being writing today. Not all of a 2000 line Lua / Go / etc module.

Would you be open to nvim-lint having a feature to filter linting issues to only show those on lines of files not yet staged in Git?

[mfussenegger]

Overall open to adding something like that but want to see more feedback first to gauge the interest in it.

[mfussenegger]

Note that a current workaround could be to use the wrap function (See https://github.com/mfussenegger/nvim-lint?tab=readme-ov-file#customize-built-in-linters) to exclude diagnostics which are not affecting new code. The wrap function can return nil to exclude a diagnostic entry.

And to figure out if a line is new or not you could probably use git status/diff or so.