Make generated props and style types augmentable

[zoontek]

Summary:

react-native-web and Nativewind extend React Native's types with module augmentation. #58062 made the props and style types interfaces, which cleared the duplicate identifier errors. Two things still can't be extended.

Styles: ViewStyle is an interface derived from ____ViewStyle_Internal, but ViewProps['style'] reads the base, so augmenting ViewStyle doesn't reach it:

declare module 'react-native' {
  interface ViewStyle { transitionDuration?: string }
}

<View style={{ transitionDuration: '1s' }} />;             // error
StyleSheet.create({ box: { transitionDuration: '1s' } });  // error

____ViewStyle_Internal is now named ViewStyle, and the same for Text and Image. StyleSheet re-exports each name unchanged, so the interface and the base are one symbol.

Props written as inline object literals: The transform copies them into the interface body, where a second declaration is a merge conflict rather than an override, so the augmentation is silently ignored. Eleven of the 24 annotated types are affected. Each now moves its inline members into a private <Name>Core alias, so they reach the interface through the extends clause and are inherited, like everything from ViewProps already was:

// before
declare interface KeyboardAvoidingViewProps extends Readonly<ViewProps> {
  readonly enabled?: boolean
}

// after
declare interface KeyboardAvoidingViewProps extends Readonly<
  ViewProps & KeyboardAvoidingViewPropsCore
> {}

That costs 11 new names in the API snapshot, one per affected type. PressableProps set the precedent with PressableBaseProps.

ImagePropsBase and ImageBackgroundProps declare members that shadow keys of the type they spread, and a Flow spread of an optional property unions the two types instead of replacing the member, so those keys get an explicit Omit.

Caveat: an augmented member has to be assignable to the inherited one. Adding a key is clean and narrowing works, but widening raises TS2430 on the declaration file, which skipLibCheck: true silences.

Changelog:

[GENERAL] [CHANGED] - Allow module augmentation to extend generated props and style types

Test Plan:

yarn build-types: all 24 annotated types now emit an empty interface body. ViewStyle, TextStyle and ImageStyle are unchanged; the props types gain the 11 <Name>Core aliases.

Compiled augmentations with skipLibCheck: false. Styles: the two lines above pass here and report TS2353 on main. Props: adding a key and narrowing an existing one on each of the 11 types passes here and reports TS2717 on main.

yarn flow-check, yarn test-generated-typescript, yarn format-check and yarn lint: clean, apart from 3 Flow errors in packages/react-native-codegen/lib already on main. yarn jest packages/react-native/Libraries packages/react-native/src scripts/js-api: 632 tests pass, no snapshot changed.

[github-actions]

Warning

JavaScript API change detected

This PR commits an update to ReactNativeApi.d.ts, indicating a change to React Native's public JavaScript API.

• Please include a clear changelog message.
• This change will be subject to additional review.

This change was flagged as: POTENTIALLY_BREAKING

[meta-codesync]

@christophpurrer has imported this pull request. If you are a Meta employee, you can view this in D117876097.

[zoontek]

@huntie @cortinico Do we have update on this PR review (and #58062)? Until then, a project with react-native-web and TS cannot really update to RN 0.87+

[cortinico]

@huntie @cortinico Do we have update on this PR review (and #58062)?

I believe that #58062 has landed no?

[zoontek]

@cortinico I don't think so, as reactwg/react-native-releases#1399 is still open and I see no trace of it in the changelogs. Also, with it alone (without this PR), ViewProps['style'], ImageProps['style'] and TextProps['style'] are reading ____ViewStyle_Internal and ____TextStyle_Internal, not the potentially extended ViewStyle and TextStyle.

EDIT: I confirm that it has landed in 0.88 latest RC, but that it doesn't fix everything and that this PR is still needed.

[cortinico]

@zoontek can you rebase and fix the conflict please?

[zoontek]

@cortinico done ✅

[meta-codesync]

@cortinico merged this pull request in 447ccd1.