Ability to automatically fix linting errors

[dsherret]

It might be useful for lints to include text changes in the lint diagnostic that would fix the diagnostic. For example, no-unused-var could return text changes that would remove unused imports.

This could then be used by a deno lint --fix command.

[kitsonk]

We should consider how we can leverage this properly in the lsp. I believe currently the only quick fixes are to insert comments to ignore the lint error, would be good to support more useful/intelligent fixes.

[dsherret]

@kitsonk oh yeah didn't think about that. That would definitely be desired. I guess it should probably have the ability to return multiple possible solutions as a fix and they should be given a description. It could use the first one for deno lint --fix and then present all the possible options to someone in the editor.

[kitsonk]

Good idea. Using roughly the pattern of the code action from the LSP protocol would make the most sense. While it doesn't have to be exactly 1-1, there should be a method on whatever structure to be able to convert it to an LSP code action.

This would also be a good way of structuring them for something like deno lint --check which would give you a preview of what changes would be done with deno lint --fix?