build: switch Makefiles and pre-commit to flat config (gh54 part VII) by Planeshifter · Pull Request #10973 · stdlib-js/stdlib

Planeshifter · 2026-03-15T18:05:32Z

Progresses stdlib-js/metr-issue-tracker#54.

Description

What is the purpose of this pull request?

This pull request:

Switches Makefiles and pre-commit hook from legacy .eslintrc.* config to flat config autodiscovery
Removes ESLINT_USE_FLAT_CONFIG=false, --ignore-path, --config, and per-target config variables from JS and TS eslint.mk.
Removes per-directory tsconfig.json copy mechanism from TS eslint.mk (flat config's TS block handles this).
Removes legacy config path variables from the pre-commit hook.
ESLint now autodiscovers eslint.config.cjs and applies rules based on file patterns.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

[RFC]: migrate to ESLint v9 metr-issue-tracker#54

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

Stacked on #10972.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

Yes
No

If you answered "yes" above, how did you use AI assistance?

Code generation (e.g., when writing an implementation or fixing a bug)
Test/benchmark generation
Documentation (including examples)
Research and understanding

Disclosure

This PR was written primarily by Claude Code.

@stdlib-js/reviewers

Add TypeScript-specific flat config blocks for `**/*.d.ts` and `**/test/**/*.ts` files: - Configure `@typescript-eslint/parser` with `parserOptions.project` pointing to the root `tsconfig.json` - Register `@typescript-eslint`, `@stylistic/ts`, `jsdoc`, `import`, `expect-type`, and `stdlib` plugins - Reuse the existing TypeScript rules from `etc/eslint/rules/typescript.js` - Disable `jsdoc/require-jsdoc` for TypeScript test files Ref: stdlib-js/metr-issue-tracker#54

Upgrade ESLint from v8 to v9 and fix all v9-specific breakages: - Bump `eslint` from `^8.57.0` to `^9.0.0` - Add `!**/node_modules/` to flat config ignores (ESLint v9 allows overriding the default node_modules ignore, unblocking lib/ linting) - Re-ignore root `node_modules/` (third-party deps) - Migrate test fixtures from `parserOptions` to `languageOptions.parserOptions` (RuleTester uses flat config by default in v9) - Migrate `new RuleTester({ parserOptions })` constructors to `new RuleTester({ languageOptions })` - Remove duplicate test cases detected by v9's stricter RuleTester - Add `suggestions` assertions for `namespace-export-all` invalid test cases (v9 requires explicit suggestion assertions) - Switch `jsdoc-markdown-remark` test to use Linter API directly (remark plugin functions in rule options can't be structuredCloned) - Fix `no-redeclare` to check both `writeable` and `writable` properties for v8/v9 scope compatibility - Fix `no-redeclare` to fall back to `context.parserOptions` when `context.languageOptions` is unavailable - Remove `builtinGlobals` invalid test cases that rely on implicit globals (not available in v9 flat config mode) - All 123 custom rule tests pass on ESLint v9 Ref: stdlib-js/metr-issue-tracker#54

Follow-up to the ESLint v9 upgrade: - Migrates the `format-args` rule tests to `languageOptions`. The rule landed on `develop` after this branch was written, so the rebase pulled it in unmigrated and its tests errored under v9 with "Key \"parserOptions\": This appears to be in eslintrc format rather than flat config format". - Narrows the flat config un-ignore from `!**/node_modules/` to `!lib/node_modules/`. The broad pattern un-ignored nested `node_modules` directories inside packages (e.g. `nyc` caches under `math/base/special/*/node_modules/`), which then got linted. The narrow pattern leaves those to ESLint's default ignores, making the separate `node_modules/` re-ignore unnecessary. Verified identical behavior across all tracked source files. - Restores the two `no-redeclare` `builtinGlobals` invalid fixtures using `languageOptions.sourceType: 'script'`. They failed under flat config because its default `sourceType` is `module`, which places `var` declarations in module rather than global scope; they do not depend on how v9 exposes implicit globals. - Regenerates `etc/npm/deps.txt` for the `eslint` and `eslint-plugin-expect-type` version bumps. All 124 custom rule tests pass on ESLint v9. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Update build tooling to use ESLint flat config (`eslint.config.js`) instead of legacy `.eslintrc.*` files: - Remove `ESLINT_USE_FLAT_CONFIG=false` from JS eslint.mk - Remove `--ignore-path`, `--config`, and per-target config variables from both JS and TS eslint.mk (flat config autodiscovery handles all of this via `eslint.config.js`) - Remove per-directory tsconfig.json copy mechanism from TS eslint.mk (the flat config's TS block points to the root tsconfig.json) - Remove legacy config path variables from pre-commit hook ESLint now autodiscovers `eslint.config.js` at the repo root and applies the correct rules based on file patterns (benchmarks, tests, examples, TypeScript) defined in the flat config. Ref: stdlib-js/metr-issue-tracker#54

Planeshifter changed the title ~~build: switch Makefiles and pre-commit to flat config~~ build: switch Makefiles and pre-commit to flat config (gh54 part VII) Mar 15, 2026

Planeshifter force-pushed the philipp/gh54-switch-to-flat-config branch from c3dab8a to c6bab92 Compare March 15, 2026 18:08

Planeshifter mentioned this pull request Mar 15, 2026

build: delete legacy ESLint config and obsolete helpers (gh54 part VIII) #10974

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Planeshifter added the METR Pull request associated with the METR project. label Mar 18, 2026

Planeshifter force-pushed the philipp/gh54-switch-to-flat-config branch from c6bab92 to 3bdcf70 Compare August 20, 2026 05:57

Planeshifter force-pushed the philipp/gh54-switch-to-flat-config branch from 3bdcf70 to 9610469 Compare August 20, 2026 06:11

Planeshifter force-pushed the philipp/gh54-switch-to-flat-config branch from 9610469 to 92735cb Compare August 20, 2026 06:25

kgryte force-pushed the philipp/gh54-switch-to-flat-config branch from 92735cb to bcb201a Compare August 21, 2026 10:06

kgryte force-pushed the philipp/gh54-switch-to-flat-config branch from bcb201a to 86526e2 Compare August 21, 2026 10:14

Planeshifter force-pushed the philipp/gh54-switch-to-flat-config branch from 86526e2 to 00d646f Compare August 25, 2026 03:49

Planeshifter and others added 4 commits August 25, 2026 18:17

kgryte force-pushed the philipp/gh54-switch-to-flat-config branch from 00d646f to a1f1006 Compare August 26, 2026 01:17

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build: switch Makefiles and pre-commit to flat config (gh54 part VII) - #10973

build: switch Makefiles and pre-commit to flat config (gh54 part VII)#10973
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Planeshifter commented Mar 15, 2026 •

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Planeshifter commented Mar 15, 2026 •

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