Bug: flat config with "eslint:all" on a .cjs file recommends function form of "use strict" instead of global form

[jzinn]

Environment

Node version: v16.14.0
npm version: 8.3.1
Local ESLint version: v8.23.1
Global ESLint version: zsh: command not found: eslint
Operating System: Fedora release 36 (Thirty Six)

What parser are you using?

Default (Espree)

What did you do?

package.json

Notice type is module.

{
  "devDependencies": {
    "eslint": "^8.23.1"
  },
  "license": "ISC",
  "name": "eslint-all-cjs",
  "scripts": {
    "lint": "eslint --fix ."
  },
  "type": "module",
  "version": "1.0.0"
}

eslint.config.js

Using the new flat config file format. The default languageOptions sourceType should be commonjs for .cjs files.

export default ["eslint:all"];

index.cjs

A .cjs file that ESLint should consider to be a commonjs file.

module.exports = function identity (value) {

    return value;

};

What did you expect to happen?

Expected: a message to use the global form of "use strict".

Why: the docs for rule strict say:

This rule has a string option:

• "safe" (default) corresponds either of the following options:
  • "global" if ESLint considers a file to be a CommonJS module
  • "function" otherwise

The file ends with .cjs, so ESLint should recommend "global".

What actually happened?

A message to use the function form:

/path/to/eslint-all-cjs/index.cjs
  1:18  error  Use the function form of 'use strict'  strict

✖ 1 problem (1 error, 0 warnings)

Participation

• I am willing to submit a pull request for this issue.

Additional comments

No response

[jzinn]

The docs for strict mention two ways to make "safe" equal "global".

The first is to set the environment to node or commonjs. I'm not sure how to do this with the new flat configuration files.

The second is to set globalReturn like this:

export default [
    "eslint:all",
    {
        "languageOptions": {
            "parserOptions": {
                "ecmaFeatures": {
                    "globalReturn": true
                }
            }
        }
    }
];

Setting globalReturn works, so I guess this issue is invalid.

It would be nice if this were a little easier to set up like by specifying the node environment if that's still possible.

Perhaps the .cjs extension should imply that the contents are a commonjs module file instead of only a commonjs file. It's a new (-ish) extension after all.

Just configuring the rule might be best:

export default [
    "eslint:all",
    {
        rules: {
            strict: ["error", "global"]
        }
    }
];

[mdjermanovic]

Hi @jzinn, thanks for the issue!

This rule has a string option:

• "safe" (default) corresponds either of the following options:

  • "global" if ESLint considers a file to be a CommonJS module
  • "function" otherwise

The file ends with .cjs, so ESLint should recommend "global".

You're right, this is a bug.

The new config system works correctly in this case, as it automatically sets sourceType: "commonjs" for .cjs files.

The problem is in the strict rule since its logic around CommonJS is based on parserOptions.ecmaFeatures.globalReturn field, which is in the new config format dropped in favor of languageOptions.sourceType = "commonjs".

I prepared PR #16308 that should fix this problem.

[oalrbabaa]

Environment

Node version: v16.14.0

npm version: 8.3.1

Local ESLint version: v8.23.1

Global ESLint version: zsh: command not found: eslint

Operating System: Fedora release 36 (Thirty Six)

What parser are you using?

Default (Espree)

What did you do?

package.json

Notice type is module.

{

  "devDependencies": {

    "eslint": "^8.23.1"

  },

  "license": "ISC",

  "name": "eslint-all-cjs",

  "scripts": {

    "lint": "eslint --fix ."

  },

  "type": "module",

  "version": "1.0.0"

}

eslint.config.js

Using the new flat config file format. The default languageOptions sourceType should be commonjs for .cjs files.

export default ["eslint:all"];

index.cjs

A .cjs file that ESLint should consider to be a commonjs file.

module.exports = function identity (value) {



    return value;



};

What did you expect to happen?

Expected: a message to use the global form of "use strict".

Why: the docs for rule strict say:

This rule has a string option:

• "safe" (default) corresponds either of the following options:

• "global" if ESLint considers a file to be a CommonJS module

• "function" otherwise

The file ends with .cjs, so ESLint should recommend "global".

What actually happened?

A message to use the function form:

/path/to/eslint-all-cjs/index.cjs

  1:18  error  Use the function form of 'use strict'  strict



✖ 1 problem (1 error, 0 warnings)

Participation

• I am willing to submit a pull request for this issue.

Additional comments

No response