@flow typeerror

[stephen-dahl]

Intended outcome:

use the @flow annotation

    @flow
    *fetch() {
      return true
    }

Actual outcome:

type error on @flow

How to reproduce the issue:

add the @flow decorator to a generator inside a class

https://codesandbox.io/p/sandbox/gifted-dawn-w2vdz9?workspaceId=6ecfa4fe-9261-4054-86f0-83188ee28c65

code sandbox does not show the error, not sure if they show ts errors. I see the error locally in vscode and webstorm.

Versions
"mobx": "^6.13.3",
"mobx-react-lite": "^4.0.7",
"typescript": "^5.6.3",

[mweststrate]

You might need to specify the return type explicitly to Generator<boolean, boolean>. Without that I had the same error: 7f10f7a

[stephen-dahl]

same error
before

after

[mweststrate]

In the sandbox you linked it fixes the issue, so it probably relates to the further compilation configuration. Are you using legacy decorators for example? As work around it might be worth trying the old onProgress = flow((..) => { } syntax

[dmitriykozlov]

Have the same issue in my project

tsconfig.json

{
  "compilerOptions": {
    "allowSyntheticDefaultImports": true
    "target": "es6",
    "lib": ["ESNext", "dom"],
    "moduleResolution": "Node",
    "esModuleInterop": true,
    "jsx": "react",
    "typeRoots": ["./typings"]
  },
}

babel

export default ({ env }) => {
  const isProduction = env('production')
  console.log('Babel isProduction=', isProduction)
  const plugins = [
    ['@babel/plugin-proposal-decorators', { version: '2023-11' }],
    [
      'babel-plugin-styled-components',
      {
        displayName: false,
        ssr: false,
        minify: isProduction,
        pure: isProduction,
      },
    ],
  ]
  if (!isProduction) {
    plugins.push(['react-refresh/babel'])
  }

  return {
    presets: [
      '@babel/preset-env',
      '@babel/preset-react',
      '@babel/preset-typescript',
    ],
    plugins,
    minified: true,
    sourceType: 'unambiguous',
  }
}

npm ls mobx mobx-react-lite typescript @babel/plugin-proposal-decorators 
[email protected] /Users/dima/WorkProjects/correqts-common
└─┬ @correqts-common/[email protected] -> ./chat
  ├── @babel/[email protected]
  ├─┬ @mobx-devtools/[email protected]
  │ └── [email protected] deduped
  ├─┬ @svgr/[email protected]
  │ └─┬ @svgr/[email protected]
  │   └─┬ [email protected]
  │     └── [email protected] deduped
  ├─┬ [email protected]
  │ └── [email protected] deduped
  ├── [email protected]
  └─┬ [email protected]
    └── [email protected]