Warn about unused linter settings

[alexandear]

I propose that Golangci-lint should raise a warning when it detects an unused linter settings.

Consider the following configuration:

version: "2"
linters:
  default: none
  enable:
    # - rowserrcheck
    - whitespace
  settings:
    rowserrcheck:
      packages:
        - github.com/jmoiron/sqlx

When running golangci-lint, it should print something like:

$ golangci-lint run
WARN The configuration setting for `rowserrcheck` is unused. Consider removing `linters.settings.rowserrcheck`.

[ldez]

I need to think about that, but this cannot be the default behavior because --enable-only exists.

[ldez]

After thinking about that, I concluded that it isn't worth the cost.
The ratio between value and maintenance cost is extremely low.
Having unused settings is not a problem, it's more of an advantage.

[bombsimon]

To add some contrast I don't think I would want this. I can see myself sharing a base config and keeping that in sync across multiple projects but only changing the enable/disable list. Keeping such config in sync is harder if I have to remove sections to avoid warnings.

Further i think sensible defaults for linters and having them easily sharable is a good thing. It would make it easier to tinker around with your preferred linter setup.

As long as it doesn't affect the lint result I don't think it's golangci-lint's job to do configuration housekeeping. For those who want this feature I think searching for the word under your cursor might be simple enough?

[alexandear]

It could be an option like settings.warn-unused, similar to exclusions.warn-unused. This way, those who need it can easily enable it without affecting others.