swc emits an arrow function for a Flow component-typed binding (hermes/babel emit a named function)

[BigPun86]

Describe the bug

swc compiles a Flow component-typed binding whose value is an arrow into an arrow function. The reference transform (hermes-parser + @react-native/babel-preset, which react-native uses) emits a named function instead. The difference matters because an arrow has no .prototype.

react-native's core components (Text, View, ScrollView, ...) are written this way, and react-native's own jest mock (react-native/jest/mockComponent.js) reads RealComponent.prototype.constructor, which throws on the arrow, so react-native can't be transformed with @swc/jest.

Input code

const MyComponent: component(ref?: mixed, ...props: mixed) = ({ ref, ...rest }) => null;

Config

{
  "jsc": {
    "parser": { "syntax": "flow", "jsx": true, "components": true },
    "target": "es2022"
  }
}

Link to the code that reproduces this issue

https://github.com/bigpun86/swc-flow-component-arrow-repro

SWC Info output

Arch: arm64
Machine Type: arm64
Version: Darwin Kernel Version 25.5.0
CPU: (16 cores) Apple M4 Max

Binaries:
Node: 24.14.1
npm: 11.11.0
Yarn: 4.17.0

Relevant Packages:
@swc/core: 1.15.43
@swc/types: 0.1.27

Expected behavior

swc emits a named function (with a .prototype), matching hermes/babel:

var MyComponent = function MyComponent(_ref) { ... };

Actual behavior

swc emits an arrow function (no .prototype):

const MyComponent = ({ ref, ...rest }) => null; // MyComponent.prototype === undefined

react-native's jest mock then throws:

TypeError: Cannot read properties of undefined (reading 'constructor')

Version

1.15.43

Additional context

The repro has two scripts: npm run repro runs react-native's real Text.js through swc (shows the arrow), npm run minimal is a runnable version that reproduces the crash. hermes/babel output verified via babel-preset-expo on the same file.

Arrows are valid JS so possibly intentional, but matching the reference would let react-native work under @swc/jest.