Flow cannot access types defined in source code

[thurt]

Description

it looks like there are lots of nice flow typing already inlined for many react native apis/components. but my flow typechecker is not able to access them in my project.

I'm guessing Flow is not able to leverage the existing types in the source, possibly due to this file using getters (flow cant resolve types from getters?) :

https://github.com/facebook/react-native/blob/0.42-stable/Libraries/react-native/react-native.js#L9

Reproduction Steps and Sample Code

Here's an example that isn't working:

// @flow
import { StatusBar } from 'react-native';

const fn = () => {
  StatusBar.setBarStyle('this-is-not-in-enum');
};

The call to StatusBar.setBarStyle should generate a flow error based on the flow types in the react-native source code. You can see that code in https://github.com/facebook/react-native/blob/0.42-stable/Libraries/Components/StatusBar/StatusBar.js#L201

My .flowconfig:

[ignore]
; We fork some components by platform
.*/*[.]android.js

; Ignore templates for 'react-native init'
.*/local-cli/templates/.*

; Ignore the website subdir
<PROJECT_ROOT>/website/.*

; Ignore "BUCK" generated dirs
<PROJECT_ROOT>/\.buckd/

; Ignore unexpected extra "@providesModule"
.*/node_modules/.*/node_modules/fbjs/.*

; Ignore duplicate module providers
; For RN Apps installed via npm, "Libraries" folder is inside
; "node_modules/react-native" but in the source repo it is in the root
.*/Libraries/react-native/React.js
.*/Libraries/react-native/ReactNative.js

[include]

[libs]
Libraries/react-native/react-native-interface.js
flow/

[options]
emoji=true

module.system=haste

experimental.strict_type_args=true

munge_underscores=true

module.name_mapper='^[./a-zA-Z0-9$_-]+\.\(bmp\|gif\|jpg\|jpeg\|png\|psd\|svg\|webp\|m4v\|mov\|mp4\|mpeg\|mpg\|webm\|aac\|aiff\|caf\|m4a\|mp3\|wav\|html\|pdf\)$' -> 'RelativeImageStub'

suppress_type=$FlowIssue
suppress_type=$FlowFixMe
suppress_type=$FixMe

suppress_comment=\\(.\\|\n\\)*\\$FlowFixMe\\($\\|[^(]\\|(\\(>=0\\.\\(3[0-8]\\|[1-2][0-9]\\|[0-9]\\).[0-9]\\)? *\\(site=[a-z,_]*react_native_oss[a-z,_]*\\)?)\\)
suppress_comment=\\(.\\|\n\\)*\\$FlowIssue\\((\\(>=0\\.\\(3[0-8]\\|1[0-9]\\|[1-2][0-9]\\).[0-9]\\)? *\\(site=[a-z,_]*react_native_oss[a-z,_]*\\)?)\\)?:? #[0-9]+
suppress_comment=\\(.\\|\n\\)*\\$FlowFixedInNextDeploy

unsafe.enable_getters_and_setters=true

[version]
^0.38.0

Additional Information

• React Native version: 0.42.3
• Platform: n/a
• Development Operating System: osx
• Dev tools: flow 0.38.0

p.s. SO issue here: http://stackoverflow.com/questions/43126131/how-to-use-react-native-flow-types

[hramos]

FWIW, generally issues that link out to SO hardly get any attention. It'd be best if the issue here contained all the necessary information.

[thurt]

@hramos thanks, updated initial post with full details

[janicduplessis]

This is actually a regression in recent RN versions, we used to do a hack to work around getters not working but they do work now so we removed the hack but didn't enable flow in react-native-implementations.js which exports all RN modules.

I have a PR up to fix this but it hasn't been reviewed yet. #12917

[ttraenkler]

In order to verify props of derived components like <MyCustomComponent> that are passed-through to a react-native primitive component like <View>, I am looking for access to built-in flowtype definitions for the props of react-native components like . In essence something that would look similar to the following if written by hand - is this possible?

type ViewProps = {
    ...Layout,
    ...Transforms,
    top?: number | Percentage,
    bottom?: number | Percentage,
    ...
}

It looks like the PR of @janicduplessis has finally been accepted.

• So does this mean I can access flow type definitions from outside in react-native only since 0.43?
• How would I access them in a standard way?
• Is this documented somewhere?
• Since I am bound to work with a version lagging behind the latest release to be in sync with react-native-web, what files do I need to backport to get flow type definitions for e.g. the <View> props?

[hramos]

Hi there! This issue is being closed because it has been inactive for a while. Maybe the issue has been fixed in a recent release, or perhaps it is not affecting a lot of people. Either way, we're automatically closing issues after a period of inactivity. Please do not take it personally!

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If you would like to work on a patch to fix the issue, contributions are very welcome! Read through the contribution guide, and feel free to hop into #react-native if you need help planning your contribution.