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

[overlookmotel]

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:

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]

• fix(linter/plugins): ensure after hook is always called in ESLint compat mode #20721 👈 (View in Graphite)
• fix(linter/plugins): fire after hook after CFG events in ESLint compat #20720
• main

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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.

[overlookmotel]

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.