[eprh] Fix recommended config for flat config compatibility
#34700
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This was referenced Oct 2, 2025
josephsavona
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Thank you for the thorough debugging on this. It's incredibly frustrating that we were following ESLint's docs, and this worked in 9.20 or so, and seems to break in more recent minors of ESLint. The new setup here is more tedious, but from your/our investigation seems to be the only reasonable compromise. Other plugins (eslint-plugin-react for example) also define separate sets of configs for legacy and flat mode too.
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Hi! I know working with ESLint is messier than it should be. Quick naming idea: |
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Comparing: 056a586...846e132 Critical size changesIncludes critical production bundles, as well as any change greater than 2%:
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Adds back the compiler rules to the recommended preset, intended for the next release. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34675). * #34703 * #34700 * #34699 * __->__ #34675
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Updates the eslint fixture lockfiles. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34699). * #34703 * #34700 * __->__ #34699 * #34675
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@hernan-yadiel the
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Previously, the `recommended` config used the legacy ESLint format (plugins as an array of strings). This causes errors when used with ESLint v9's `defineConfig()` helper. This was following [eslint's own docs](https://eslint.org/docs/latest/extend/plugins#backwards-compatibility-for-legacy-configs): > With this approach, both configuration systems recognize "recommended". The old config system uses the recommended key while the current config system uses the flat/recommended key. The defineConfig() helper first looks at the recommended key, and if that is not in the correct format, it looks for the flat/recommended key. This allows you an upgrade path if you’d later like to rename flat/recommended to recommended when you no longer need to support the old config system. However, [`isLegacyConfig()`](https://github.com/eslint/rewrite/blob/main/packages/config-helpers/src/define-config.js#L73-L81) (also see [`eslintrcKeys`](https://github.com/eslint/rewrite/blob/main/packages/config-helpers/src/define-config.js#L24-L35)) function doesn't check for the `plugins` key, so our config was incorrectly treated as flat config despite being in legacy format. This PR fixes the issue, along with a few other fixes combined: 1. Convert `recommended` to flat config format 2. Separate basic rules (exhaustive-deps, rules-of-hooks) from compiler rules 3. Add `recommended-latest-legacy` config for non-flat config users who want all recommended rules (including compiler rules) 4. Adding more types for the exported config Our shipped presets in 6.x.x will essentially be: - `recommended-legacy`: legacy (non-flat), with basic rules only - `recommended-latest-legacy`: legacy (non-flat), all rules (basic + compiler) - `flat/recommended`: flat, basic rules only (now the same as recommended, but to avoid making a breaking change we'll just keep it around in 6.x.x) - `recommended-latest`: flat, all rules (basic + compiler) - `recommended`: flat, basic rules only In the next breaking release 7.x.x, we will collapse down the presets into three: - `recommended-legacy`: all recommended rules - `recommended`: all recommended rules - `recommended-experimental`: all recommended rules + new bleeding edge experimental rules Closes #34679
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Updates the eslint fixture lockfiles. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34699). * #34703 * #34700 * __->__ #34699 * #34675 DiffTrain build for [056a586](056a586)
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Updates the eslint fixture lockfiles. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34699). * #34703 * #34700 * __->__ #34699 * #34675 DiffTrain build for [056a586](056a586)
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Previously, the `recommended` config used the legacy ESLint format (plugins as an array of strings). This causes errors when used with ESLint v9's `defineConfig()` helper. This was following [eslint's own docs](https://eslint.org/docs/latest/extend/plugins#backwards-compatibility-for-legacy-configs): > With this approach, both configuration systems recognize "recommended". The old config system uses the recommended key while the current config system uses the flat/recommended key. The defineConfig() helper first looks at the recommended key, and if that is not in the correct format, it looks for the flat/recommended key. This allows you an upgrade path if you’d later like to rename flat/recommended to recommended when you no longer need to support the old config system. However, [`isLegacyConfig()`](https://github.com/eslint/rewrite/blob/main/packages/config-helpers/src/define-config.js#L73-L81) (also see [`eslintrcKeys`](https://github.com/eslint/rewrite/blob/main/packages/config-helpers/src/define-config.js#L24-L35)) function doesn't check for the `plugins` key, so our config was incorrectly treated as flat config despite being in legacy format. This PR fixes the issue, along with a few other fixes combined: 1. Convert `recommended` to flat config format 2. Separate basic rules (exhaustive-deps, rules-of-hooks) from compiler rules 3. Add `recommended-latest-legacy` config for non-flat config users who want all recommended rules (including compiler rules) 4. Adding more types for the exported config Our shipped presets in 6.x.x will essentially be: - `recommended-legacy`: legacy (non-flat), with basic rules only - `recommended-latest-legacy`: legacy (non-flat), all rules (basic + compiler) - `flat/recommended`: flat, basic rules only (now the same as recommended, but to avoid making a breaking change we'll just keep it around in 6.x.x) - `recommended-latest`: flat, all rules (basic + compiler) - `recommended`: flat, basic rules only In the next breaking release 7.x.x, we will collapse down the presets into three: - `recommended-legacy`: all recommended rules - `recommended`: all recommended rules - `recommended-experimental`: all recommended rules + new bleeding edge experimental rules Closes #34679 --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34700). * #34703 * __->__ #34700 DiffTrain build for [26b177b](26b177b)
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Previously, the `recommended` config used the legacy ESLint format (plugins as an array of strings). This causes errors when used with ESLint v9's `defineConfig()` helper. This was following [eslint's own docs](https://eslint.org/docs/latest/extend/plugins#backwards-compatibility-for-legacy-configs): > With this approach, both configuration systems recognize "recommended". The old config system uses the recommended key while the current config system uses the flat/recommended key. The defineConfig() helper first looks at the recommended key, and if that is not in the correct format, it looks for the flat/recommended key. This allows you an upgrade path if you’d later like to rename flat/recommended to recommended when you no longer need to support the old config system. However, [`isLegacyConfig()`](https://github.com/eslint/rewrite/blob/main/packages/config-helpers/src/define-config.js#L73-L81) (also see [`eslintrcKeys`](https://github.com/eslint/rewrite/blob/main/packages/config-helpers/src/define-config.js#L24-L35)) function doesn't check for the `plugins` key, so our config was incorrectly treated as flat config despite being in legacy format. This PR fixes the issue, along with a few other fixes combined: 1. Convert `recommended` to flat config format 2. Separate basic rules (exhaustive-deps, rules-of-hooks) from compiler rules 3. Add `recommended-latest-legacy` config for non-flat config users who want all recommended rules (including compiler rules) 4. Adding more types for the exported config Our shipped presets in 6.x.x will essentially be: - `recommended-legacy`: legacy (non-flat), with basic rules only - `recommended-latest-legacy`: legacy (non-flat), all rules (basic + compiler) - `flat/recommended`: flat, basic rules only (now the same as recommended, but to avoid making a breaking change we'll just keep it around in 6.x.x) - `recommended-latest`: flat, all rules (basic + compiler) - `recommended`: flat, basic rules only In the next breaking release 7.x.x, we will collapse down the presets into three: - `recommended-legacy`: all recommended rules - `recommended`: all recommended rules - `recommended-experimental`: all recommended rules + new bleeding edge experimental rules Closes #34679 --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34700). * #34703 * __->__ #34700 DiffTrain build for [26b177b](26b177b)
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This rule was a leftover from a while ago and doesn't actually lint anything useful. Specifically, you get a lint error if you try to opt out a component that isn't already bailing out. If there's a bailout the compiler already safely skips over it, so adding `'use no memo'` there is unnecessary. Fixes #31407 --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34703). * __->__ #34703 * #34700
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This rule was a leftover from a while ago and doesn't actually lint anything useful. Specifically, you get a lint error if you try to opt out a component that isn't already bailing out. If there's a bailout the compiler already safely skips over it, so adding `'use no memo'` there is unnecessary. Fixes #31407 --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34703). * __->__ #34703 * #34700 DiffTrain build for [19f65ff](19f65ff)
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This rule was a leftover from a while ago and doesn't actually lint anything useful. Specifically, you get a lint error if you try to opt out a component that isn't already bailing out. If there's a bailout the compiler already safely skips over it, so adding `'use no memo'` there is unnecessary. Fixes #31407 --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34703). * __->__ #34703 * #34700 DiffTrain build for [19f65ff](19f65ff)
This was referenced Oct 3, 2025
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This rule was a leftover from a while ago and doesn't actually lint anything useful. Specifically, you get a lint error if you try to opt out a component that isn't already bailing out. If there's a bailout the compiler already safely skips over it, so adding `'use no memo'` there is unnecessary. Fixes facebook#31407 --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34703). * __->__ facebook#34703 * facebook#34700 DiffTrain build for [19f65ff](facebook@19f65ff)
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This rule was a leftover from a while ago and doesn't actually lint anything useful. Specifically, you get a lint error if you try to opt out a component that isn't already bailing out. If there's a bailout the compiler already safely skips over it, so adding `'use no memo'` there is unnecessary. Fixes facebook#31407 --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34703). * __->__ facebook#34703 * facebook#34700 DiffTrain build for [19f65ff](facebook@19f65ff)
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Previously, the
recommendedconfig used the legacy ESLint format (plugins as an array of strings). This causes errors when used with ESLint v9'sdefineConfig()helper. This was following eslint's own docs:However,
isLegacyConfig()(also seeeslintrcKeys) function doesn't check for thepluginskey, so our config was incorrectly treated as flat config despite being in legacy format.This PR fixes the issue, along with a few other fixes combined:
recommendedto flat config formatrecommended-latest-legacyconfig for non-flat config users who want all recommended rules (including compiler rules)Our shipped presets in 6.x.x will essentially be:
recommended-legacy: legacy (non-flat), with basic rules onlyrecommended-latest-legacy: legacy (non-flat), all rules (basic + compiler)flat/recommended: flat, basic rules only (now the same as recommended, but to avoid making a breaking change we'll just keep it around in 6.x.x)recommended-latest: flat, all rules (basic + compiler)recommended: flat, basic rules onlyIn the next breaking release 7.x.x, we will collapse down the presets into three:
recommended-legacy: all recommended rulesrecommended: all recommended rulesrecommended-experimental: all recommended rules + new bleeding edge experimental rulesCloses #34679
Stack created with Sapling. Best reviewed with ReviewStack.
recommendedconfig for flat config compatibility #34700