Support XO v1+ by patrik-csak · Pull Request #1819 · webpro-nl/knip

patrik-csak · 2026-06-25T19:18:35Z

Summary

Update XO plugin to support XO v1+
- Update config and entry to support XO v1+ config files
- Update types
- Determine ESLint config type (flat or deprecated) based on installed XO version
Rename xo fixture to xo-0 and create new xo fixture for XO v1+
- Translate fixtures/plugins/xo-0/.xo-config.js to fixtures/plugins/xo/xo.config.js
  - Create mock eslint-plugin-unused-imports because in eslint flat config, plugins can't be referenced by string, they must be imported
- Translate fixtures/plugins/xo-0/xo.config.cjs to fixtures/plugins/xo/xo.config.ts
Rename mock config glob to my-shared-config for clarity

XO config history

xo version	supported configs	change from previous
v0	`package.json`, `.xo-config.{js,cjs,json}`, `xo.config.{js,cjs}`
v1	`package.json`, `xo.config.{js,cjs,mjs,ts,cts,mts}`	require flat config, drop `.xo-config.*`
v2	`package.json`, `xo.config.{js,mjs,ts,mts}`	drop `xo.config.{cjs,cts}`
v3	"	none

Copilot

Pull request overview

Adds XO v1+ (flat-config era) support to Knip’s XO plugin by expanding supported config filenames, distinguishing XO v0 vs v1+ behavior in tests/fixtures, and allowing ESLint config input extraction to be overridden for non-eslint.config.* flat configs.

Changes:

Extend XO plugin config/entry globs to include xo.config.{mjs,ts,cts,mts} and introduce XO-major-based flat/deprecated handling.
Add separate fixture + test coverage for XO v0 (.xo-config.* / deprecated config shape) vs XO v1+ (flat xo.config.*).
Update ESLint helper getInputs to accept an optional “flat config override” flag (used by the XO plugin).

Reviewed changes

Copilot reviewed 10 out of 19 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/knip/src/plugins/xo/index.ts	Adds XO major-version detection and treats `xo.config.*` as flat-config inputs.
packages/knip/src/plugins/xo/types.ts	Broadens XO config typing to support both v0 deprecated configs and v1+ flat config items/arrays.
packages/knip/src/plugins/eslint/helpers.ts	Adds `isFlatConfigOverride` param to route non-`eslint.config.*` configs through flat/deprecated extraction.
packages/knip/test/plugins/xo.test.ts	Updates XO plugin test to assert unlisted deps from flat `xo.config.{js,ts}` fixtures.
packages/knip/test/plugins/xo-0.test.ts	Adds XO v0-specific test asserting deprecated `.xo-config.*` and package.json plugin resolution.
packages/knip/fixtures/plugins/xo/package.json	Updates fixture to XO `^3.0.2` and removes deprecated `plugins` field usage.
packages/knip/fixtures/plugins/xo/xo.config.js	Adds flat XO config file importing `eslint-plugin-unused-imports` (to be detected as unlisted).
packages/knip/fixtures/plugins/xo/xo.config.ts	Adds flat XO config file importing `my-shared-config` (to be detected as unlisted).
packages/knip/fixtures/plugins/xo/node_modules/my-shared-config/package.json	Adds dummy resolvable package for `my-shared-config` fixture import.
packages/knip/fixtures/plugins/xo/node_modules/my-shared-config/index.js	Provides the module content for `my-shared-config`.
packages/knip/fixtures/plugins/xo/node_modules/eslint-plugin-unused-imports/package.json	Adds dummy resolvable package for `eslint-plugin-unused-imports` fixture import.
packages/knip/fixtures/plugins/xo/node_modules/eslint-plugin-unused-imports/index.js	Provides the module content for `eslint-plugin-unused-imports`.
packages/knip/fixtures/plugins/xo-0/package.json	Adds XO v0 fixture manifest (XO `^0.60.0`) with deprecated package.json config.
packages/knip/fixtures/plugins/xo-0/.xo-config.js	Adds XO v0 deprecated `.xo-config.js` fixture that references `unused-imports`.
packages/knip/fixtures/plugins/xo-0/xo.config.cjs	Adjusts XO v0 `xo.config.cjs` fixture to require `my-shared-config`.
packages/knip/fixtures/plugins/xo-0/node_modules/xo/package.json	Fixes dummy package name to `xo` for the XO v0 fixture environment.
packages/knip/fixtures/plugins/xo-0/node_modules/my-shared-config/package.json	Adds dummy resolvable package for the XO v0 fixture require.

patrik-csak · 2026-06-25T19:54:45Z

renamed from packages/knip/fixtures/plugins/xo/package.json

patrik-csak · 2026-06-25T19:56:25Z

-    "plugins": [
-      "eslint-comments"
-    ]


This isn’t possible in XO v1+

https://github.com/xojs/xo/tree/v3.0.2#shareable-configs

patrik-csak · 2026-06-25T19:57:04Z

Copied from packages/knip/fixtures/plugins/xo-0/xo.config.js and converted to flat config

patrik-csak · 2026-06-25T19:57:26Z

Copied from packages/knip/fixtures/plugins/xo-0/xo.config.ts and converted to flat config

patrik-csak · 2026-06-25T20:01:54Z

+  options: PluginOptions,
+  isFlatConfigOverride?: boolean
 ): (Input | ConfigInput)[] => {
  const { configFileName } = options;

-  if (extname(configFileName) === '.json' || !isFlatConfig(configFileName)) {
+  const isFlatConfigFile =
+    isFlatConfigOverride ?? (extname(configFileName) !== '.json' && isFlatConfig(configFileName));
+
+  if (!isFlatConfigFile) {


This is a quick and dirty way to allow the XO plugin to determine whether the config is flat or deprecated. I didn’t spend much time on it, assuming that it would need to be discussed.

patrik-csak · 2026-06-25T20:04:28Z


 const resolveConfig: ResolveConfig<XOConfig> = async (config, options) => {
-  const inputs = getInputs(config, options);
+  const xoVersion = options.manifest.getMajor('xo') ?? 3;


Falling back to the latest version to match behavior of the react email plugin

knip/packages/knip/src/plugins/react-email/index.ts

Line 23 in 6b328d5

const dep = (manifest.getMajor('react-email') ?? 6) >= 6 ? '@react-email/ui' : '@react-email/preview-server';

patrik-csak · 2026-06-25T20:05:52Z

Renamed from packages/knip/test/plugins/xo.test.ts

patrik-csak · 2026-06-25T20:27:46Z

+  assert(issues.unlisted['xo.config.js']['eslint-plugin-unused-imports']);
+  assert(issues.unlisted['xo.config.ts']['my-shared-config']);



eslint-plugin-unused-imports changes from unresolved to unlisted because it must be imported in flat config as opposed to referenced by string in deprecated config

+ import unusedImports from 'eslint-plugin-unused-imports'; … - plugins: ['unused-imports'], + plugins: { + 'unused-imports': unusedImports, + }, …

Renamed glob to my-shared-config

Removed package.json unresolved plugin check because XO v1+ only supports serializable values in package.json.xo, so there's nothing we can add to package.json.xo to exercise Knip

webpro · 2026-06-26T13:31:28Z

Thanks for the PR! Would you mind if I add a commit and you can review that? I think we could simplify a bit here.

patrik-csak · 2026-06-26T15:42:19Z

Not at all!

xo@1+ uses ESLint flat config: plugins are referenced via `import`, so they're already detected as entry-file imports. Resolve those configs from the AST (reusing the ESLint flat-config resolver) and skip loading them, gated on the installed xo major. xo@0 keeps the loaded eslintrc path. - Mirrors the ESLint plugin (isLoadConfig=false + resolveFromAST for flat) - Avoids spurious "Error loading xo.config.*" when a config spreads real plugins (executing them can throw, e.g. on an uninstalled peer) - Drops the getInputs override and the unused flat config type

webpro · 2026-06-26T16:37:09Z

There you go, let me know what you think. Imho it doesn't have to be all that perfect across each and every version of xo, as long as we grab entry points and dependencies properly.

pkg-pr-new · 2026-06-26T16:37:52Z

Open in StackBlitz

npm i https://pkg.pr.new/knip@1819

npm i https://pkg.pr.new/@knip/language-server@1819

npm i https://pkg.pr.new/@knip/mcp@1819

commit: 613d09e

patrik-csak · 2026-06-26T17:16:04Z

Looks good to me

webpro · 2026-06-27T13:11:41Z

🚀 This pull request is included in v6.22.0. See Release 6.22.0 for release notes.

Using Knip in a commercial project? Please consider becoming a sponsor.

Rename mock config

c1fb119

Copilot AI review requested due to automatic review settings June 25, 2026 19:18

Copilot started reviewing on behalf of patrik-csak June 25, 2026 19:18 View session

Copilot AI reviewed Jun 25, 2026

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Comment thread packages/knip/src/plugins/xo/index.ts Outdated

patrik-csak marked this pull request as draft June 25, 2026 19:31

Support XO v1+

a54edb9

patrik-csak force-pushed the xo branch from 61ae820 to a54edb9 Compare June 25, 2026 20:08

patrik-csak commented Jun 25, 2026

View reviewed changes

patrik-csak marked this pull request as ready for review June 25, 2026 20:29

webpro merged commit 1dffe36 into webpro-nl:main Jun 27, 2026
30 checks passed

		assert(issues.unlisted['xo.config.js']['eslint-plugin-unused-imports']);
		assert(issues.unlisted['xo.config.ts']['my-shared-config']);

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patrik-csak commented Jun 25, 2026 •

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