fix(linter/plugins): ensure `after` hook is always called in ESLint compat mode by overlookmotel · Pull Request #20721 · oxc-project/oxc

overlookmotel · 2026-03-24T23:57:57Z

In Oxlint, when using createOnce API, we ensure that after hooks are always called for all rules even in the event of a rule throwing an error during AST traversal.

Uphold the same guarantee when a plugin using createOnce API runs in ESLint via eslintCompatPlugin, including in language server environments where the process lives on after an error is thrown.

We now make sure that:

after hooks are always run even if an error occurs during AST visitation.
after hooks for all rules are always run after all the plugin's rules complete AST visitation (not just after each individual rule finishes AST visitation).

These guarantees allow creating a reliable per-file cache shared between rules with a pattern like this:

let cache: Data | null = null;

let numRunningRules = 0;

function setupCache(context) {
  if (cache === null) cache = new Data(context);
  numRunningRules++;
}

function teardownCache() {
  numRunningRules--;
  if (numRunningRules === 0) cache = null;
}

const rule1 = {
  createOnce(context) {
    return {
      before() {
        setupCache(context);
      },
      Identifier(node) {
        // Use `cache`
      },
      after() {
        teardownCache();
      },
    };
  },
};

const rule2 = {
  // Same as above
};

const rule3 = {
  // Same as above
};

We can build on this to create a dedicated API for the shared cache use case, and have it work reliably in ESLint as well as Oxlint. Related: #20700.

overlookmotel · 2026-03-24T23:58:10Z

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Copilot

Pull request overview

Improves ESLint compatibility for Oxlint createOnce plugins by ensuring after hooks are executed reliably (including after visitor/CFG errors) and only after all rules in the plugin finish traversing a file. Adds fixture-based coverage in both Oxlint and ESLint snapshot modes for multiple error scenarios and ordering guarantees.

Changes:

Add plugin-wide AfterHooksState coordination in eslintCompatPlugin to run all pending after hooks after traversal and still clean up on errors.
Expand eslintCompat fixture to verify after hooks run after all CFG events across multiple rules.
Add new fixtures validating after hook execution/order when errors occur in before, visitor functions, CFG handlers, and after.

Reviewed changes

Copilot reviewed 34 out of 34 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
apps/oxlint/src-js/package/compat.ts	Implement plugin-wide `after` hook scheduling/reset logic for ESLint compat mode.
apps/oxlint/test/fixtures/eslintCompat/plugin.ts	Extend CFG-order fixture to include two CFG rules and assert cross-rule ordering.
apps/oxlint/test/fixtures/eslintCompat/output.snap.md	Update Oxlint snapshot output for added CFG rule.
apps/oxlint/test/fixtures/eslintCompat/eslint.snap.md	Update ESLint snapshot output for added CFG rule.
apps/oxlint/test/fixtures/eslintCompat/eslint.config.js	Enable new CFG rule in ESLint config.
apps/oxlint/test/fixtures/eslintCompat/.oxlintrc.json	Enable new CFG rule in Oxlint config.
apps/oxlint/test/fixtures/eslintCompat_error_in_visit/plugin.ts	New fixture plugin: throws in an AST visitor and logs hook order.
apps/oxlint/test/fixtures/eslintCompat_error_in_visit/output.snap.md	Oxlint snapshot for visitor-throw scenario.
apps/oxlint/test/fixtures/eslintCompat_error_in_visit/options.json	Fixture options enabling ESLint compat mode.
apps/oxlint/test/fixtures/eslintCompat_error_in_visit/files/1.js	Fixture input file.
apps/oxlint/test/fixtures/eslintCompat_error_in_visit/eslint.snap.md	ESLint snapshot for visitor-throw scenario.
apps/oxlint/test/fixtures/eslintCompat_error_in_visit/eslint.config.js	ESLint config for visitor-throw fixture.
apps/oxlint/test/fixtures/eslintCompat_error_in_visit/.oxlintrc.json	Oxlint config for visitor-throw fixture.
apps/oxlint/test/fixtures/eslintCompat_error_in_onCodePathEnd/plugin.ts	New fixture plugin: throws in `onCodePathEnd` and logs hook order.
apps/oxlint/test/fixtures/eslintCompat_error_in_onCodePathEnd/output.snap.md	Oxlint snapshot for CFG handler-throw scenario.
apps/oxlint/test/fixtures/eslintCompat_error_in_onCodePathEnd/options.json	Fixture options enabling ESLint compat mode.
apps/oxlint/test/fixtures/eslintCompat_error_in_onCodePathEnd/files/1.js	Fixture input file.
apps/oxlint/test/fixtures/eslintCompat_error_in_onCodePathEnd/eslint.snap.md	ESLint snapshot for CFG handler-throw scenario.
apps/oxlint/test/fixtures/eslintCompat_error_in_onCodePathEnd/eslint.config.js	ESLint config for CFG handler-throw fixture.
apps/oxlint/test/fixtures/eslintCompat_error_in_onCodePathEnd/.oxlintrc.json	Oxlint config for CFG handler-throw fixture.
apps/oxlint/test/fixtures/eslintCompat_error_in_before/plugin.ts	New fixture plugin: throws in `before` and validates which `after` hooks run.
apps/oxlint/test/fixtures/eslintCompat_error_in_before/output.snap.md	Oxlint snapshot for `before`-throw scenario.
apps/oxlint/test/fixtures/eslintCompat_error_in_before/options.json	Fixture options enabling ESLint compat mode.
apps/oxlint/test/fixtures/eslintCompat_error_in_before/files/1.js	Fixture input file.
apps/oxlint/test/fixtures/eslintCompat_error_in_before/eslint.snap.md	ESLint snapshot for `before`-throw scenario.
apps/oxlint/test/fixtures/eslintCompat_error_in_before/eslint.config.js	ESLint config for `before`-throw fixture.
apps/oxlint/test/fixtures/eslintCompat_error_in_before/.oxlintrc.json	Oxlint config for `before`-throw fixture.
apps/oxlint/test/fixtures/eslintCompat_error_in_after/plugin.ts	New fixture plugin: throws in `after` and ensures other `after` hooks still run.
apps/oxlint/test/fixtures/eslintCompat_error_in_after/output.snap.md	Oxlint snapshot for `after`-throw scenario.
apps/oxlint/test/fixtures/eslintCompat_error_in_after/options.json	Fixture options enabling ESLint compat mode.
apps/oxlint/test/fixtures/eslintCompat_error_in_after/files/1.js	Fixture input file.
apps/oxlint/test/fixtures/eslintCompat_error_in_after/eslint.snap.md	ESLint snapshot for `after`-throw scenario.
apps/oxlint/test/fixtures/eslintCompat_error_in_after/eslint.config.js	ESLint config for `after`-throw fixture.
apps/oxlint/test/fixtures/eslintCompat_error_in_after/.oxlintrc.json	Oxlint config for `after`-throw fixture.

apps/oxlint/test/fixtures/eslintCompat_error_in_onCodePathEnd/plugin.ts

apps/oxlint/src-js/package/compat.ts

apps/oxlint/test/fixtures/eslintCompat/plugin.ts

apps/oxlint/test/fixtures/eslintCompat_error_in_onCodePathEnd/plugin.ts

overlookmotel · 2026-03-25T01:00:47Z

Merge activity

Mar 25, 1:00 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Mar 25, 1:00 AM UTC: overlookmotel added this pull request to the Graphite merge queue.
Mar 25, 1:06 AM UTC: Merged by the Graphite merge queue.

…ompat mode (#20721) In Oxlint, when using `createOnce` API, we ensure that `after` hooks are always called for all rules even in the event of a rule throwing an error during AST traversal. Uphold the same guarantee when a plugin using `createOnce` API runs in ESLint via `eslintCompatPlugin`, including in language server environments where the process lives on after an error is thrown. We now make sure that: 1. `after` hooks are always run even if an error occurs during AST visitation. 2. `after` hooks for all rules are always run after *all* the plugin's rules complete AST visitation (not just after each individual rule finishes AST visitation). These guarantees allow creating a reliable per-file cache shared between rules with a pattern like this: ```ts let cache: Data | null = null; let numRunningRules = 0; function setupCache(context) { if (cache === null) cache = new Data(context); numRunningRules++; } function teardownCache() { numRunningRules--; if (numRunningRules === 0) cache = null; } const rule1 = { createOnce(context) { return { before() { setupCache(context); }, Identifier(node) { // Use `cache` }, after() { teardownCache(); }, }; }, }; const rule2 = { // Same as above }; const rule3 = { // Same as above }; ``` We can build on this to create a dedicated API for the shared cache use case, and have it work reliably in ESLint as well as Oxlint. Related: #20700.

# Oxlint ### 💥 BREAKING CHANGES - c0ebbce linter: [**BREAKING**] Report error on unknown builtin rule (#20464) (camc314) ### 🚀 Features - 04f85e5 linter/no-unused-vars: Add safe-fix option for import fixes (#20839) (Marcell Toth) - 32a3706 linter/eslint-vitest-plugin: Implements `require-test-timeout` rule (#20806) (Said Atrahouch) - ae03653 linter: Implement suggestion for `eslint/no-useless-computed-key` rule (#20805) (Mikhail Baev) - 6624513 linter/prefer-string-starts-ends-with: Move rule from nursery to style (#20797) (camc314) - 58941f8 linter/prefer-readonly: Move rule from nursery to style (#20796) (camc314) - 8837ffd linter/prefer-regexp-exec: Move rule from nursery to style (#20795) (camc314) - 7e88871 linter/prefer-find: Move rule out of nursery (#20794) (camc314) - ca6e5bc linter/vitest: Implement prefer-called-exactly-once-with (#17562) (Said Atrahouch) - e80c0bf linter/eslint-plugin-vitest: Implement `require-mock-type-parameters` (#20785) (Said Atrahouch) - cec8b8f linter/vitest: Implement require-awaited-expect-poll rule (#20702) (Said Atrahouch) - d8e9d01 linter/eslint-plugin-vitest: Set `prefer-to-have-been-called-times` compatible with jest (#20703) (Said Atrahouch) - caf8231 linter: Enhance import plugin diagnostics with help messages (#20766) (离谱) - f44adfa linter: Improve the oxlint config generated by `--init`. (#20632) (connorshea) - 43f4827 linter: Add help text to jest and promise diagnostics (#20640) (kszongic) - 16516de linter: Enhance types for `DummyRule` (#20751) (camc314) - 27374e8 linter: Add hint about node version when ts config fail to import (#20570) (camc314) - 8e34150 linter/eslint-plugin-vitest: Sync rule with JS implementation (#20679) (Said Atrahouch) ### 🐛 Bug Fixes - df057d5 linter/no-noninteractive-tabindex: Add missing composite widget … (#20860) (bab) - bb34073 linter: Mark vitest/valid-title as a compatible jest rules (#20463) (Nicolas Le Cam) - bd2c76b linter: Handle shadowed locals in no-restricted-globals (#20811) (Ulrich Stark) - 62e39be linter: Sort nested object keys in fix of `eslint/sort-keys` in one pass (#20838) (Ulrich Stark) - 3ef37da oxlint/lsp: Error on unknown command (#20841) (Sysix) - ab1070d oxlint/cli: Skip parsing base config again for nested config search (#20809) (Sysix) - 2be3728 oxlint/lsp: Skip parsing base config again for nested config search (#20808) (Sysix) - 6171217 oxlint: Respect `NO_COLOR` env for `format=stylish` (#20804) (Sysix) - d89ae8f linter/plugins: Patch `WeakMap` to emulate `WeakMap`s keyed by `sourceCode` (#20799) (overlookmotel) - c610666 linter/no-shadow: Respect env settings when builtinGlobals is enabled (#20429) (vvnikita74) - 6bb502f linter/no-invalid-void-type: Allow void generic args in heritage clauses (#20780) (camc314) - 365bb7d linter: Skip typed nested literals in explicit-module-boundary-types (#20776) (camc314) - 0aa1ff0 linter/plugins: Ensure `after` hook is always called in ESLint compat mode (#20721) (overlookmotel) - 31145a9 linter/plugins: Fire `after` hook after CFG events in ESLint compat (#20720) (overlookmotel) - c09a5ab diagnostics: Skip minified fallback for single-line reporters (#20716) (camc314) - e4dc9a1 linter: Isolate `--init` config writes from parallel tests (#20717) (camc314) - 7e394ec linter: Clarify empty replacement fixer help text (#20698) (camc314) - d15a99c linter/jsx-curly-brace-presence: Flag empty string literals (#20690) (camc314) ### 📚 Documentation - c722495 linter: Update JS Plugins + LS references (#20843) (camc314) - e1f9748 linter/jsdoc/require-property: Fix typo (#20792) (Benjaming61001) - be3dcc1 linter: Add note about node version + custom TS plugin (#19381) (camc314) # Oxfmt ### 🚀 Features - 6ef440a oxfmt: Support bool for object style options (#20853) (leaysgur) - 23050fa oxfmt: Support markdown-in-js substitution (#20683) (leaysgur) - 4087295 oxfmt: Support angular-in-js substitution (#20676) (leaysgur)

github-actions bot added A-linter Area - Linter A-cli Area - CLI A-linter-plugins Area - Linter JS plugins labels Mar 24, 2026

overlookmotel mentioned this pull request Mar 24, 2026

fix(linter/plugins): fire after hook after CFG events in ESLint compat #20720

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github-actions bot added the C-bug Category - Bug label Mar 24, 2026

overlookmotel force-pushed the om/03-24-fix_linter_plugins_ensure_after_hook_is_always_called_in_eslint_compat_mode branch from 0061f54 to 20abf3c Compare March 25, 2026 00:10

overlookmotel marked this pull request as ready for review March 25, 2026 00:18

overlookmotel requested a review from camc314 as a code owner March 25, 2026 00:18

Copilot AI review requested due to automatic review settings March 25, 2026 00:18

Copilot started reviewing on behalf of overlookmotel March 25, 2026 00:18 View session

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overlookmotel force-pushed the om/03-24-fix_linter_plugins_ensure_after_hook_is_always_called_in_eslint_compat_mode branch from 20abf3c to 4d271fe Compare March 25, 2026 00:32

overlookmotel added the 0-merge Merge with Graphite Merge Queue label Mar 25, 2026

graphite-app bot force-pushed the om/03-24-fix_linter_plugins_fire_after_hook_after_cfg_events_in_eslint_compat branch from 694fdb1 to 31145a9 Compare March 25, 2026 01:02

graphite-app bot force-pushed the om/03-24-fix_linter_plugins_ensure_after_hook_is_always_called_in_eslint_compat_mode branch from 4d271fe to 0aa1ff0 Compare March 25, 2026 01:02

Base automatically changed from om/03-24-fix_linter_plugins_fire_after_hook_after_cfg_events_in_eslint_compat to main March 25, 2026 01:05

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graphite-app bot merged commit 0aa1ff0 into main Mar 25, 2026
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graphite-app bot deleted the om/03-24-fix_linter_plugins_ensure_after_hook_is_always_called_in_eslint_compat_mode branch March 25, 2026 01:06

overlookmotel mentioned this pull request Mar 27, 2026

Linter plugins: Add APIs to support sharing per-file data between rules #20700

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Boshen mentioned this pull request Mar 30, 2026

release(apps): oxlint v1.58.0 && oxfmt v0.43.0 #20867

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fix(linter/plugins): ensure `after` hook is always called in ESLint compat mode#20721

fix(linter/plugins): ensure `after` hook is always called in ESLint compat mode#20721
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