Cannot resolve module when running Flow on Windows

[zenz]

Environment

Run react-native info in your terminal and paste its contents here.
react-native info

React Native Environment Info:
System:
OS: Windows 10
CPU: x64 Intel(R) Core(TM) i5-7200U CPU @ 2.50GHz
Memory: 2.09 GB / 7.91 GB
Binaries:
Yarn: 1.9.4 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
npm: 6.1.0 - C:\Program Files\nodejs\npm.CMD

Description

using flow not working and got error with "Cannot resolve module XXXXXX". but same action under macOS works well.

Reproducible Demo

react-native init testapp
cd testapp
yarn add flow-bin@0.78.0 --dev
yarn flow

under windows will get errors.

[zenz]

with

"@babel/runtime": "^7.1.2",
 "metro-react-native-babel-preset": "0.48.0",

The issue seems had been fixed. So I close this now.

Sorry, the above didn't solve the issue. the error gone just because I put // @flow after imports.

[zenz]

Sorry, the above didn't solve the issue. the error gone just because I put // @flow after imports.

[zenz]

No other one using flow under windows or don't have any problem on this?

[jlkalberer]

I had the issue but I just added more ignores to the flowconfig

[zenz]

0.57.4 is released now, but this issue is not solved yet.
waiting.....

[gengjiawen]

I have contact with core members, maybe an issue related to metro.

[zenz]

@gengjiawen Thank you!

[gengjiawen]

@TheSavior Looks like a flow issue, can you find some people work on this ?

$ flow check --flowconfig-name .flowconfig.android
Error --------------------------------------------------------------- IntegrationTests/AccessibilityManagerTest.js:16:39

Cannot resolve module `RCTDeviceEventEmitter`.

   16| const RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
                                             ^^^^^^^^^^^^^^^^^^^^^^^


Error -------------------------------------------------------------------------- IntegrationTests/AppEventsTest.js:18:28

Cannot resolve module `deepDiffer`.

   18| const deepDiffer = require('deepDiffer');

[gengjiawen]

I have reported to flow team too facebook/flow#7138.

[gengjiawen]

Update: fb look into this, hopefully we can fix this soon.

[jamesisaac]

I believe this should fix it: facebook/flow#7419

[zenz]

@jamesisaac Thank you for the information. It's not yet apply to release package yet. So I will just wait because I don't want to compile it by myself.

[gengjiawen]

@jamesisaac Looks like still not working, see windows build on this pr: #21401.

[jamesisaac]

@gengjiawen Unrelated error? Or am I looking in the wrong place? Here all I see is:

C:\projects\react-native\node_modules\flow-bin\cli.js:17
  throw new Error('Platform not supported.');
  ^

I.e. Flow is not even starting correctly on AppVeyor. Whereas this issue is about the "Cannot resolve module" error once Flow does run.

Had a quick look at cli.js but I'm not really familiar with the pattern they're trying to use there, so not sure why it's not working on AppVeyor.

[gengjiawen]

Is it because the flow server still has bug on windows ?
The appveyor env

System:
    OS: Windows 8.1
    CPU: (2) ia32 Intel(R) Xeon(R) CPU E5-2697 v3 @ 2.60GHz
    Memory: 2.90 GB / 4.88 GB
  Binaries:
    Node: 10.15.1 - C:\Program Files (x86)\nodejs\node.EXE
    Yarn: 1.9.4 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
    npm: 6.4.1 - C:\Program Files (x86)\nodejs\npm.CMD
  SDKs:
    Android SDK:
      Android NDK: 17.2.4988734
  Languages:
    Bash: 4.4.19 - C:\Program Files\Git\usr\bin\bash.EXE
    Go: 1.11 - C:\go\bin\go.EXE
    Perl: 5.22.1 - C:\Perl\bin\perl.EXE
    Python: 2.7.15 - /c/Python27/python
    Ruby: 1.9.3 - C:\Ruby193\bin\ruby.EXE
  Browsers:
    Internet Explorer: 11.0.9600.19036

[gengjiawen]

Also on my windows 10 it still failed with

npm ERR! code ELIFECYCLE
npm ERR! errno 110
npm ERR! react-native@1000.0.0 flow-check-android: `flow check --flowconfig-name .flowconfig.android`
npm ERR! Exit status 110
npm ERR! 
npm ERR! Failed at the react-native@1000.0.0 flow-check-android script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

Flow seems pretty much unusable in windows.

[jamesisaac]

On my Win10 machine this works fine in Git Bash and PowerShell:

$ git clone https://github.com/facebook/react-native
$ cd react-native
$ yarn install

$ yarn flow
# Flow check finishes, 2 errors about `unclear-type` (`any` usage).
# Prior to fix it would have come back with hundreds of "Cannot resolve module" errors.

$ yarn run flow-check-android
# Again, flow check finishes with 2 `unclear-type` errors.

Try running yarn flow instead of yarn run flow-check-android as it gives more real-time output. But I do think this is an unrelated issue to the one in this topic / my PR.

[zenz]

with react-native@0.59.0-rc3 and flow-bin@0.93.0(not 0.92.0), this issue gone.

[gengjiawen]

Glad it works. But still need to do work on this repo since there is another issue on windows. I will close this issue for now.