[Getting Started] Error: ignoring return value of function declared with warn_unused_result attribute

[andresn]

Hi there, I'm snagged after a fresh install today:

$ react-native init AwesomeProject
$ react-native run-ios

Full log:
https://gist.github.com/andresn/1f35d718da9fc57542bb399460f2efd0#file-gistfile1-txt-L109

react-native@0.28.0
react-native-cli@1.0.0
XCode Beta 8.0
Mac OS X El Capitan v.10.11.5

I think this is specific to having Xcode-beta 8.0 installed, because running the app through beta-7.3 does work.

[liweiz]

I had similar experience today. But it was on macOS beta. Build failed on both XCode 7.3.1 (7D1014) and 8.0 beta 2 (8S162m). I did try $ react-native run-ios but got error:

ERROR ENOENT: no such file or directory, lstat '/AwesomeProject/ios/build/ModuleCache/3F1D94PC0NUP2/AVFoundation-1M2ASOEW37WIZ.pcm-53d428b3'
{"errno":-2,"code":"ENOENT","syscall":"lstat","path":"/AwesomeProject/ios/build/ModuleCache/3F1D94PC0NUP2/AVFoundation-1M2ASOEW37WIZ.pcm-53d428b3"}
Error: ENOENT: no such file or directory, lstat '/AwesomeProject/ios/build/ModuleCache/3F1D94PC0NUP2/AVFoundation-1M2ASOEW37WIZ.pcm-53d428b3'
at Error (native)

macOS: 10.12 Beta (16A239j)
react-native-cli: 1.0.0
react-native: 0.29.0

Same two errors on both versions of XCode under Semantic Issue, when I tried build with XCode:

• /AwesomeProject/node_modules/react-native/Libraries/WebSocket/RCTSRWebSocket.m:494:3: Ignoring return value of function declared with warn_unused_result attribute
  

• /AwesomeProject/node_modules/react-native/Libraries/WebSocket/RCTSRWebSocket.m:1334:5: Ignoring return value of function declared with warn_unused_result attribute
  

Edit: Sorry, I forgot to mention that I was not able to install watchman.

[samtgarson]

+1 on this, getting almost exactly the same output as OP 😭

Could be related to #8108?

[cpruijsen]

I'm also facing this error :(

[crsanthony]

same :(

[huangkaiw3n]

I'm running into this issue as well. I'm on Xcode Version 8.0 beta 2. And OS X 10.11.5. I've got almost the same log too

[jlietart]

Same issue here :(

[adeolafadeyibi]

Same issue here:(

[zhaop4133]

Same issue here:(

[isramartinez]

Same issue here on Xcode version 8.0 beta 3

[adeolafadeyibi]

I uninstalled Xcode version 8.0 beta 3 and installed 7.3 and now everything works fine.

[TimBroddin]

Just doubleclick on the RCTWebSocket project in your navigator and remove the flags under build settings > custom compiler flags

Your project should compile just fine now!

[alessiodionisi]

@TimBroddin Thank you!!

[jdmarshall]

Having the same issue, but on XCode 7.2.1

I think the fact that upgrading XCode fixes this for some people has more to do with temporary files being retained somewhere and the installer deletes them.

What is the -proper- way to clear a working directory and rerun a build with react-native? I'm having problems with rebuilding and having components that have been deleted or renamed still causing errors, which means that some part of the build is not removing intermediate results between builds.