prefer-object-rule false positives

[aladdin-add]

I've just tried eslint-plugin-eslint-plugin@4.0.0-0 in eslint repo.

/Users/weiran/repo/github/eslint/karma.conf.js
  13:18  error  Rules should be declared using the object style  eslint-plugin/prefer-object-rule

/Users/weiran/repo/github/eslint/lib/cli-engine/formatters/checkstyle.js
  31:18  error  Rules should be declared using the object style  eslint-plugin/prefer-object-rule
.....

We can suggest users to use overrides to avoid these cases?

[bmish]

I think this is a pre-existing issue. That's why ESLint only enables the eslint-plugin/prefer-object-rule for rule files: https://github.com/eslint/eslint/blob/c4fffbcb089182d425ef1d5e45134fecc0e2da46/.eslintrc.js#L88

It's showing up now because we added this rule to the recommended config, so we'll just have to disable it in some places instead (or only enable the rules-recommended config for the rules folder).

[aladdin-add]

I was thinking it can be a docs improvement - suggest using overrides to only apply the plugin to rule/test files.

or we will have to remove it from the recommended - it could be confusing for inexperienced users.

[bmish]

I opened a doc improvement for this in #204.

I would strongly prefer to keep eslint-plugin/prefer-object-rule as a recommended rule, especially since I'm planning to write an RFC to remove function-style rule support from ESLint in v9, so it's important that we discourage their use.

However, if necessary, as a bug fix, we could make our function-style rule detection more strict. Instead of just looking for:

• module.exports = function (context) { ... }
• export default function (context) { ... }

We could look for a default-exported function that has at least one object return:

• module.exports = function (context) { return { ... } }
• export default function (context) { return { ... } }

This would help reduce false positives.