1881701 - (eslint-flat) Migrate ESLint configuration to flat config

Status: RESOLVED FIXED

(Developer Infrastructure :: Lint and Formatting, task, P3)

Description

[Mark Banner (:standard8)]

In upgrading to ESLint v9, we think we can first migrate to the flat configuration in v8, before upgrading to v9 itself.

To do this we'll need to fix the issues this depends on and then investigate:

• Importing the ESLint ignore file.
  • Secondary thought: could it be merged/shared with the prettier file?
• Are there any more simple sub-level .eslintrc.js files that could be cleaned up and merged into the top-level config, or their parents?
• Convert the top-level .eslintrc.js file to eslint.config.mjs
  • For the sub-level .eslintrc.js files, load those (via an explicit list), into the top-level configuration and add them to the list of configurations.

Comment 1

[Mark Banner (:standard8)]

I now have patches for this. They are a bit complex, but seem to work, and there's probably going to be lots of follow-ups to do later. However, aiming to get these landed before the 140 freeze, so that ESR will at least have all the changed settings files, in case changes need to be uplifted.

Comment 2

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Configure testing/mochitest/tests/Harness_sanity/ test setup with eslintrc-test-paths rather than its own .eslintrc.js set-up. r?#frontend-codestyle-reviewers!

Comment 3

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Rename many ESLint files to use .mjs. r?#frontend-codestyle-reviewers!

This is separate to help preserve history of the files.

Comment 4

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Add some utility functions to eslint-plugin-mozilla to support flat config processing. r?#frontend-codestyle-reviewers!

This also sets up recommended.js to match against the required file extensions, which is needed for the configuration to work correctly.

Comment 5

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Change the devtools configurations to work with the ESLint flat configuration.r?#devtools-reviewers!

This consolidates the jest environment definition, and the xpcshell globals into the devtools/.eslintrc.mjs file, for easier configurations.
It also changes the restart of the configurations to work with flat config.

Comment 6

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Change new .eslintrc.mjs files to modules (browser/), and export as flat config. r?#frontend-codestyle-reviewers!

Comment 7

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Change new .eslintrc.mjs files to modules (toolkit/), and export as flat config. r?#frontend-codestyle-reviewers!

Comment 8

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Change new .eslintrc.mjs files to modules (misc), and export as flat config. r?#frontend-codestyle-reviewers!

Comment 9

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Switch the main ESLint configuration to use the flat configuration. r?#frontend-codestyle-reviewers!

Comment 10

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Change how ESLint valid/require-jsdoc configurations are applied, so that the config is applied before sub-configs. r?#frontend-codestyle-reviewers!

This helps fix raised issues in customizable UI code which turns rules off in its own directory.

Comment 11

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Fix ESLint issues shown up by improved configuration application. r?#frontend-codestyle-reviewers!

Comment 12

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Add toolkit/modules/third_party to ThirdPartyPaths.txt. r?#frontend-codestyle-reviewers!

Comment 13

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Automatically fix new issues raised in devtools. r?#devtools-reviewers!

Comment 14

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Fix remainder of newly raised devtools issues after switching to the ESLint flat config. r?#devtools-reviewers!

Comment 15

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Fix python tests related to the ESLint linter. r?#linter-reviewers!

Comment 16

[Mark Banner (:standard8)]

Attachment: Bug 1881701 - Move ESLint ignores and test paths to be module files as well. r?#frontend-codestyle-reviewers!

This completes the moving of all the top-level configuration files to be ES modules, and named similarily.

Comment 17

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/eb2701d51897
Configure testing/mochitest/tests/Harness_sanity/ test setup with eslintrc-test-paths rather than its own .eslintrc.js set-up. r=frontend-codestyle-reviewers,Gijs
https://hg.mozilla.org/integration/autoland/rev/d3114c8f716e
Rename many ESLint files to use .mjs. r=frontend-codestyle-reviewers,perftest-reviewers,Gijs,sparky,webcompat-reviewers,twisniewski
https://hg.mozilla.org/integration/autoland/rev/e3c80f00b02b
Add some utility functions to eslint-plugin-mozilla to support flat config processing. r=frontend-codestyle-reviewers,Gijs
https://hg.mozilla.org/integration/autoland/rev/000233049ab0
Change the devtools configurations to work with the ESLint flat configuration.r=devtools-reviewers,profiler-reviewers,julienw,nchevobbe
https://hg.mozilla.org/integration/autoland/rev/30bb0943828a
Change new .eslintrc.mjs files to modules (browser/), and export as flat config. r=frontend-codestyle-reviewers,extension-reviewers,pip-reviewers,credential-management-reviewers,search-reviewers,places-reviewers,omc-reviewers,migration-reviewers,home-newtab-reviewers,urlbar-reviewers,aminomancer,daisuke,dimi,robwu,jteow,mconley
https://hg.mozilla.org/integration/autoland/rev/22e7ea4dde93
Change new .eslintrc.mjs files to modules (toolkit/), and export as flat config. r=frontend-codestyle-reviewers,extension-reviewers,credential-management-reviewers,Gijs,mossop,dimi,robwu
https://hg.mozilla.org/integration/autoland/rev/2d52ba4350fd
Change new .eslintrc.mjs files to modules (misc), and export as flat config. r=frontend-codestyle-reviewers,webdriver-reviewers,perftest-reviewers,geckoview-reviewers,devtools-reviewers,sync-reviewers,android-reviewers,mossop,spidermonkey-reviewers,Gijs,ohall,whimboo,nchevobbe,arai,sparky,skhamis,webcompat-reviewers,twisniewski
https://hg.mozilla.org/integration/autoland/rev/1f962d559236
Switch the main ESLint configuration to use the flat configuration. r=frontend-codestyle-reviewers,Gijs
https://hg.mozilla.org/integration/autoland/rev/62ad4b186ae9
Change how ESLint valid/require-jsdoc configurations are applied, so that the config is applied before sub-configs. r=frontend-codestyle-reviewers,mossop
https://hg.mozilla.org/integration/autoland/rev/363a2a5d0a21
Fix ESLint issues shown up by improved configuration application. r=frontend-codestyle-reviewers,application-update-reviewers,credential-management-reviewers,bytesized,dimi
https://hg.mozilla.org/integration/autoland/rev/968062cd7933
Add toolkit/modules/third_party to ThirdPartyPaths.txt. r=frontend-codestyle-reviewers,mossop
https://hg.mozilla.org/integration/autoland/rev/07433b508a89
Automatically fix new issues raised in devtools. r=devtools-reviewers,frontend-codestyle-reviewers,mossop,nchevobbe
https://hg.mozilla.org/integration/autoland/rev/c78852cfbe1b
Fix remainder of newly raised devtools issues after switching to the ESLint flat config. r=devtools-reviewers,frontend-codestyle-reviewers,mossop,nchevobbe
https://hg.mozilla.org/integration/autoland/rev/8a96bebed69f
Fix python tests related to the ESLint linter. r=linter-reviewers,frontend-codestyle-reviewers,sylvestre
https://hg.mozilla.org/integration/autoland/rev/a58949ca6435
Move ESLint ignores and test paths to be module files as well. r=frontend-codestyle-reviewers,devtools-reviewers,Gijs,nchevobbe

Comment 18

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/eb2701d51897
https://hg.mozilla.org/mozilla-central/rev/d3114c8f716e
https://hg.mozilla.org/mozilla-central/rev/e3c80f00b02b
https://hg.mozilla.org/mozilla-central/rev/000233049ab0
https://hg.mozilla.org/mozilla-central/rev/30bb0943828a
https://hg.mozilla.org/mozilla-central/rev/22e7ea4dde93
https://hg.mozilla.org/mozilla-central/rev/2d52ba4350fd
https://hg.mozilla.org/mozilla-central/rev/1f962d559236
https://hg.mozilla.org/mozilla-central/rev/62ad4b186ae9
https://hg.mozilla.org/mozilla-central/rev/363a2a5d0a21
https://hg.mozilla.org/mozilla-central/rev/968062cd7933
https://hg.mozilla.org/mozilla-central/rev/07433b508a89
https://hg.mozilla.org/mozilla-central/rev/c78852cfbe1b
https://hg.mozilla.org/mozilla-central/rev/8a96bebed69f
https://hg.mozilla.org/mozilla-central/rev/a58949ca6435