Babel transformer: Use envName to hint default value of dev, don't mutate process.env.BABEL_ENV#55806
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Babel transformer: Use envName to hint default value of dev, don't mutate process.env.BABEL_ENV#55806
envName to hint default value of dev, don't mutate process.env.BABEL_ENV#55806Conversation
…hDevTools`, infer from `env()` instead. (#55805) Summary: Currently the RN Babel preset has this surprising bit of behaviour: ```js module.exports = (options, babel) => { if (options.withDevTools == null) { const env = process.env.BABEL_ENV || process.env.NODE_ENV; if (!env || env === 'development') { return getPreset(null, {...options, dev: true}, babel); } } return getPreset(null, options, babel); }; ``` If the (undocumented, otherwise unused) `withDevTools` option is set (to anything), we will override any given value of `dev` to `true` if `BABEL_ENV` || `NODE_ENV || 'development' === 'development'`. To put that another way, with `NODE_ENV=development` and `BABEL_ENV` unset, we would always produce a dev bundle even if `{ dev: false }` Expo sets `withDevTools: false` to stop this happening, and always set `dev` (so this diff means **no observable change under Expo**): https://github.com/expo/expo/blob/4a46dbff7a5a77d9fe06d30a70d7fab38cfc7f9a/packages/babel-preset-expo/build/index.js#L235-L236 This odd-looking override was introduced in 2017 in bc22a4d / D5237158 as a way to gate `babel/plugin-transform-react-jsx-source`, *before the preset accepted any other options* - it was never intended to override `dev`. Now, we gate that same plugin under `options.dev`. ## Inferring `dev` when unspecified The one potentially load-bearing piece of this is that, when a consumer specifies neither `withDevTools` nor `dev` (or maybe no options at all), this code serves to infer it from `process.env.BABEL_ENV || process.env.NODE_ENV`, which is reasonable and actually closer to the way typical plugins/presets work, but a better mechanism compatible with Babel's cache is to use the `env()` API (which defaults to `process.env.BABEL_ENV || process.env.NODE_ENV`, so preserves behaviour). https://babeljs.io/docs/config-files#apienv ## This change - Removes the obsolete use of `withDevToolss`, and never overrides the explicitly-passed `dev` - Where `dev` is not specified, falls back to the Babel environment. Changelog: [General][Fixed] Babel-preset: Don't override explicitly-passed `dev` config if obsolete `withDevTools` is missing Reviewed By: huntie Differential Revision: D94660480
…t mutate `process.env.BABEL_ENV` Summary: After #55805, the RN Babel preset no longer reads `process.env.BABEL_ENV` directly, instead using Babel's `env()` API, which is both cache-aware and properly respects explicit `envName` config. See: - https://babeljs.io/docs/config-files#apienv - https://babeljs.io/docs/options#envname Now, instead of mutating `process.env.BABEL_ENV` to force the environment for a transform, we can specify `envName` instead. Changelog: [Internal] Differential Revision: D94662935
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Summary:
After #55805, the RN Babel preset no longer reads
process.env.BABEL_ENVdirectly, instead using Babel'senv()API, which is both cache-aware and properly respects explicitenvNameconfig.See:
Now, instead of mutating
process.env.BABEL_ENVto force the environment for a transform, we can specifyenvNameinstead.Changelog: [Internal]
Differential Revision: D94662935