New: extends in glob-based config (fixes #8813)

[mysticatea]

What is the purpose of this pull request? (put an "X" next to item)

[X] Add something to the core: fixes #8813

What changes did you make? (Give an overview)

This PR adds support for extends and nested overrides in overrides setting.

Both nested overrides settings and the overrides settings in extended configs in a overrides item work similarly. Those settings will be applied only when both glob patterns of the parent overrides and the child overrides were matched.

Is there anything you'd like reviewers to focus on?

Nothing in particular.

[mysticatea]

I'm not sure why "commit-message" check failed 🤔

[mysticatea]

I updated this PR and I believe ready for review.

[mysticatea]

Thank you for your review!

[aladdin-add]

LGTM, thanks!

[platinumazure]

LGTM, thanks! Just left one question.

[mysticatea]

(If I use GitHub review feature to bundle multiple replies, GitHub seems to show those duplicate. 😕 )

[gziolo]

It looks like overrides inherits also basePath for filtering files from the location of the config file when using extend making it not that much useful when consuming config published to npm. Related PR where I discovered it: WordPress/gutenberg-examples#87 (comment)

This is the line which sets basePath based on the location of the file:

eslint/lib/cli-engine/config-array-factory.js

Line 485 in 00d2c5b

const basePath = filePath ? path.dirname(filePath) : cwd;

Example of the override:

criteria:
     { includes: [Array],
       excludes: null,
       basePath:
        '/Users/gziolo/PhpstormProjects/gutenberg-examples/node_modules/@wordpress/scripts/config' },

which obviously can't match any files in the project.

[platinumazure]

@gziolo Would you mind opening a new issue? Thanks!

[gziolo]

I think it's similar to #12032. I commented there. I wanted to do more research before jumping into creating a new issue :)