[feature] LSP: inform user when rule is invalid

[chrisgrieser]

When you use ast-grep as LSP, you are not informed when the linting is not performed due to an invalid rule. Took me a while to come up with the idea to try ast-grep scan in the terminal, which revealed that an invalid rule was the cause:

> ast-grep scan
Error: Cannot parse rule {...}/short-var-names.yml
Help: The file is not a valid ast-grep rule. Please refer to doc and fix the error.
See also: https://ast-grep.github.io/guide/rule-config.html

✖ Caused by
╰▻ Fail to parse yaml as RuleConfig
╰▻ missing field `id` at line 11 column 1

I'd suggest displaying a diagnostic at line one with the info "invalid rule...", to inform the user why no linting is taking place.

[HerringtonDarkholme]

Thanks for the suggestion! It sounds like an LSP client feature to me. Are you using neovim?

[chrisgrieser]

yeah, I am.

Nonetheless, I think simply adding a diagnostic stating "config invalid" would already help a lot, and that could be done without any changes on lsp client side?

[HerringtonDarkholme]

The issue is that lsp only checks source code not config YAML.
It may be worth adding editing support for rule completion/diagnostic in LSP.