Environment

Node version: v22.14.0
npm version: v10.9.2
Local ESLint version: v9.28.0
Global ESLint version: no
Operating System: windows

What parser are you using?

Default (Espree)

What did you do?

export default [
    {
        files: [["**/*.myjs", "src/**"]],
        rules: {
            "no-undef": 2
        }
    }
];

// src/foo.myjs
foo

What did you expect to happen?

I'd expect all .myjs files in src directory to be included in linting.

What actually happened?

$ npx eslint src/foo.myjs

C:\projects\tmp\tmp\src\foo.myjs
  0:0  warning  File ignored because no matching configuration was supplied

✖ 1 problem (0 errors, 1 warning)

Link to Minimal Reproducible Example

https://stackblitz.com/edit/stackblitz-starters-vajknonf

Participation

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

Additional comments

This is because the code that checks whether a pattern is an explicit match doesn't account for arrays in files:

https://github.com/eslint/rewrite/blob/cb858ffb8b77ea76187a857546c7a838a1fb4881/packages/config-array/src/config-array.js#L1013-L1054

If the order is changed to files: [["src/**", "**/*.myjs"]], then it is considered explicit match, by chance due to the way arrays are coerced to strings.