Summary:
Though not currently in use in the RN code, when `react-native-windows` tried to integrate changes up to 7/28/23 (see PR https://github.com/microsoft/react-native-windows/pull/11970) there happened to be a `??=` operator in the `virtualized-lists` package (see [diff here](https://github.com/facebook/react-native/compare/ccc50ddd2...c168a4f88#diff-abeff2daf5909e54a23562e43569de1d5b8db1d7170119eed485b618cdf04ec7R322)). (The offending line was removed in a later commit).
The default RNW engine is still Chakra and it couldn't handle the syntax. It looks like the `babel/plugin-proposal-nullish-coalescing-operator` plugin only handles `??`, so to handle `??=` I've added `babel/plugin-proposal-logical-assignment-operators`, which also happens to handle the logical assignment operators `||=` and `&&=`.
Closes https://github.com/facebook/react-native/issues/31704
## Changelog:
[GENERAL] [FIXED] - Add detection of logical assignment operators to `react-native-babel-preset`
Pull Request resolved: https://github.com/facebook/react-native/pull/39186
Test Plan: We started using these plugins in RNW's babel config to resolve the issue in our integrate PR.
Reviewed By: motiz88
Differential Revision: D50936554
Pulled By: rozele
fbshipit-source-id: 0a924b6085524d8c9551a158b91195b1f7448c19
Summary:
Hermes supports arrows. I assume the only reason the transform wasn't dropped is due to the scary TODO.
Originally, the arrow transform was conditional like this:
```js
if (isNull || src.indexOf('=>') !== -1) {
extraPlugins.push(es2015ArrowFunctions);
}
```
I made it unconditional in https://github.com/facebook/metro/commit/beb3d1ab5dc46a856e0810f3c0787f8885c8f654 (D15947985) to work around an issue where React Refresh Babel plugin emitted arrow functions. However, I fixed that plugin to _not_ emit arrow functions a long time ago in https://github.com/facebook/react/pull/15956. So this TODO is effectively solved, and has been, for ages.
In this commit, we:
- Skip the transform for Hermes altogether
- For non-Hermes, revert to the old conditional behavior
Possible alternatives:
- We could skip it for Hermes but apply unconditionally otherwise (a bit simpler)
- Or, if all target non-Hermes runtimes already support it natively, we could completely remove it
## Changelog:
[GENERAL] [CHANGED] - Apply Babel arrow transform only on non-Hermes
Pull Request resolved: https://github.com/facebook/react-native/pull/41253
Test Plan: Run fbsource tests (that's for you, not for me :)
Reviewed By: NickGerleman
Differential Revision: D50818568
Pulled By: robhogan
fbshipit-source-id: ad96540bb7778792d38a6ddec06999d2acf620d0
Summary:
X-link: https://github.com/facebook/metro/pull/1078
Pull Request resolved: https://github.com/facebook/react-native/pull/39159
Source is not required for `getPreset` of `react-native/babel-preset`. There is a codition that adds `react-native/babel-plugin-codegen` to the preset only if source is passing certain regex. This condition fails if source is null, but that's wrong because the plugin may still be requred for this transformation even though source is not provided.
This diff changes the condition so the regexp tests source only if it is not null, and `react-native/babel-plugin-codegen` automatically added to the preset otherwise.
Changelog: [Internal]
Reviewed By: robhogan
Differential Revision: D48684443
fbshipit-source-id: 7cea69c91c0175ac0374d72e91f58e20fe75fd53
Summary:
X-link: https://github.com/facebook/metro/pull/1024
Pull Request resolved: https://github.com/facebook/react-native/pull/38228
Changelog: [General][Changed] - Move react-native-babel-transformer and react-native-babel-preset from Metro to React Native repo.
Metro Changelog: **[Breaking]** - Remove `metro-react-native-babel-transformer` and `metro-react-native-babel-preset`, to be published as `react-native/metro-babel-transformer` and `react-native/babel-preset` instead.
This diff does the following:
- Move `metro/packages/metro-react-native-babel-preset` to `react-native/packages/react-native-babel-preset`.
- Rename `metro-react-native-babel-preset` package to `react-native/babel-preset`.
- Move `metro/packages/metro-react-native-babel-transformer` to `react-native/packages/react-native-babel-transformer`.
- Rename `metro-react-native-babel-transformer` package to `react-native/metro-babel-transformer`.
- Upadate dependencies.
Reviewed By: robhogan
Differential Revision: D46977466
fbshipit-source-id: 32478f63a0442b61a1804f12ef814c8b29d7f8bb
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