[iOS] pod lib lint React.podspec --subspec='Core' did not pass validation

[JesseRom]

• [ x ] Review the documentation: https://facebook.github.io/react-native
• [ x ] Search for existing issues: https://github.com/facebook/react-native/issues
• [ x ] Use the latest React Native release: https://github.com/facebook/react-native/releases

Environment

Environment:
OS: macOS High Sierra 10.13.4
Node: 9.3.0
Yarn: 1.7.0
npm: 5.6.0
Watchman: 4.9.0
Xcode: Xcode 9.4.1 Build version 9F2000
Android Studio: Not Found

Packages: (wanted => installed)
react: ^16.3.1 => 16.4.1
react-native: 0.55.4 => 0.55.4

Core subspec

s.subspec "Core" do |ss|
ss.dependency "Yoga", "#{package["version"]}.React"
ss.source_files = "React//*.{c,h,m,mm,S,cpp}"
ss.exclude_files = "/tests/",
"IntegrationTests/",
"React/DevSupport/",
"React/Inspector/",
"ReactCommon/yoga/",
"React/Cxx/",
"React/Fabric/",
ss.ios.exclude_files = "React/**/RCTTV*."
ss.tvos.exclude_files = "React/Modules/RCTClipboard",
"React/Views/RCTDatePicker*",
"React/Views/RCTPicker*",
"React/Views/RCTRefreshControl*",
"React/Views/RCTSlider*",
"React/Views/RCTSwitch*",
"React/Views/RCTWebView*"
ss.header_dir = "React"
ss.framework = "JavaScriptCore"
ss.libraries = "stdc++"
ss.pod_target_xcconfig = { "HEADER_SEARCH_PATHS" => ""$(PODS_TARGET_SRCROOT)/ReactCommon"" }
end

Description

I want to make a react-native private pod using the React.podspec file in the node_modules/react-native directory, but I am using the following command:
pod lib lint React.podspec --sources='git@gitlab.xiaoenai.net:ios/xspecs.git,https://github.com/CocoaPods/Specs' --allow-warnings --verbose --subspec=' Core'
When verifying the subspec 'Core', the following error was reported:
    ** BUILD FAILED **
    
    The following build commands failed:
    CompileC /Users/JesseRom/Library/Developer/Xcode/DerivedData/App-cobxrvjzprxgjhbaftnqmampbnkm/Build/Intermediates.noindex/Pods.build/Release-iphonesimulator/React.build/Objects-normal/i386/RCTDevSettings.o React/React/Modules /RCTDevSettings.mm normal i386 objective-c++ com.apple.compilers.llvm.clang.1_0.compiler
    (1 failure)
   Testing with xcodebuild.
 -> React/Core (0.55.4)
    - ERROR | [iOS] [React/Core] xcodebuild: Returned an unsuccessful exit code.
    - WARN | [iOS] [React/Core] xcodebuild: React/React/Base/RCTConvert.m:356:1: warning: implicit conversion loses integer precision: 'unsigned long long' to 'UIDataDetectorTypes' (aka 'enum UIDataDetectorTypes' ) [-Wshorten-64-to-32]
    - NOTE | [iOS] [React/Core] xcodebuild: React/React/Modules/RCTDevSettings.mm:14:9: fatal error: 'jschelpers/JavaScriptCore.h' file not found
    - WARN | [React/Core] xcodebuild: React/React/Base/Surface/SurfaceHostingView/RCTSurfaceHostingView.h:17:16: warning: pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness ]
    - NOTE | [React/Core] xcodebuild: React/React/Base/Surface/SurfaceHostingView/RCTSurfaceHostingView.h:17:16: note: insert '_Nullable' if the pointer may be null
    - NOTE | [React/Core] xcodebuild: React/React/Base/Surface/SurfaceHostingView/RCTSurfaceHostingView.h:17:16: note: insert '_Nonnull' if the pointer should never be null

Analyzed 1 podspec.

[!] The spec did not pass validation, due to 1 error.
You can use the --no-clean option to inspect any issue.

When I am confused why the subspec ‘Core’ cannot be verified. 
From the given error message - NOTE | [iOS] [React/Core] xcodebuild: React/React/Modules/RCTDevSettings.mm:14:9: fatal error: 'jschelpers/JavaScriptCore.h' file not found
It seems that the subspec ‘Core’ dependency on the subspec ‘jschelpers’

How to deal with this issue, any suggestions?

[stale]

Hey there, it looks like there has been no activity on this issue recently. Has the issue been fixed, or does it still require the community's attention? This issue may be closed if no further activity occurs. You may also label this issue as "For Discussion" or "Good first issue" and I will leave it open. Thank you for your contributions.

[stale]

Closing this issue after a prolonged period of inactivity. If this issue is still present in the latest release, please feel free to create a new issue with up-to-date information.