Bug: C++ types from imported module '__ObjC' do not support library evolution

[serjooo]

How were you trying to build the app?

Build Type

Xcode build (cmd+b)

I also tried running the project with the following command, similarly as the example app build:ios

xcodebuild -workspace SharedMobileModules.xcworkspace -scheme ReactSharedModules -skipPackagePluginValidation -skipMacroValidation -configuration Debug -sdk iphonesimulator CC=clang CPLUSPLUS=clang++ LD=clang LDPLUSPLUS=clang++ GCC_OPTIMIZATION_LEVEL=0 GCC_PRECOMPILE_PREFIX_HEADER=YES ASSETCATALOG_COMPILER_OPTIMIZATION=time DEBUG_INFORMATION_FORMAT=dwarf COMPILER_INDEX_STORE_ENABLE=NO

Project Context

Developing and building a Brownfield React Native Framework that is published through SPM and AAR Artifactory. The error happens when building the famework target on Xcode.

• iOS Version: 16.6
• Xcode version: 16.2

Debugging

I tried disabling the Xcode build setting Build Libraries for Distribution. This is already set to No on pods. However, this might not be ideal in our case because we distribute our Brownfield React Native setup as a SPM package.

Full build logs

Build ReactSharedModules_2025-06-13T14-38-50.txt

Update

I also checked the Swift Compiler - Language and changed it to be C++ / Objective-C++ instead of C / Objective-C. This helped. I have a different error output now:

log.txt

Project dependencies

// Root package.json dependencies
"devDependencies": {
    "@actions/core": "^1.11.1",
    "@actions/github": "^5.1.1",
    "@eslint-react/eslint-plugin": "^1.40.1",
    "@graphql-codegen/cli": "^5.0.5",
    "@lodev09/react-native-true-sheet": "2.0.3",
    "@parcel/watcher": "^2.5.1",
    "@react-native-masked-view/masked-view": "0.3.2",
    "@react-native/eslint-config": "^0.73.1",
    "@react-navigation/native": "^7.0.13",
    "@react-navigation/native-stack": "^7.1.14",
    "@testing-library/react-native": "^12.9.0",
    "@types/jest": "^29.5.14",
    "@types/lodash": "^4",
    "@types/react": "^18.2.44",
    "@types/react-test-renderer": "^18",
    "@types/sanitize-html": "2",
    "@typescript-eslint/eslint-plugin": "^8.29.0",
    "@typescript-eslint/parser": "^8.29.0",
    "@zest/react-native": "0.0.49",
    "ajv-cli": "^5.0.0",
    "eslint": "^8.51.0",
    "eslint-config-prettier": "^9.0.0",
    "eslint-import-resolver-typescript": "^4.3.1",
    "eslint-plugin-custom-rules": "workspace:^",
    "eslint-plugin-design-system-tracker": "workspace:^",
    "eslint-plugin-filenames-simple": "^0.9.0",
    "eslint-plugin-import": "^2.31.0",
    "eslint-plugin-jest": "^28.9.0",
    "eslint-plugin-prefer-arrow": "^1.2.3",
    "eslint-plugin-prettier": "^5.0.1",
    "eslint-plugin-react": "^7.37.4",
    "eslint-plugin-react-native": "^5.0.0",
    "eslint-plugin-testing-library": "^7.0.0",
    "glob": "^11.0.0",
    "husky": "^9.1.7",
    "jest": "^29.7.0",
    "jest-environment-jsdom": "^29.7.0",
    "kleur": "^4.1.5",
    "lint-staged": "^15.2.10",
    "nitro-codegen": "^0.26.2",
    "plop": "^4.0.1",
    "prettier": "^3.0.3",
    "quicktype": "^23.0.170",
    "react": "18.3.1",
    "react-native": "0.75.4",
    "react-native-builder-bob": "^0.30.2",
    "react-native-nitro-modules": "^0.26.2",
    "react-native-pager-view": "6.7.0",
    "react-native-reanimated": "3.16.7",
    "react-native-restart": "^0.0.27",
    "react-native-safe-area-context": "4.14.1",
    "react-native-screens": "^4.3.0",
    "react-native-svg": "15.10.0",
    "react-test-renderer": "18.3.1",
    "ts-node": "^10.9.2",
    "typescript": "5.1.6"
},
"dependencies": {
    "@apollo/client": "^3.13.6",
    "@lokalise/node-api": "^14.0.0",
    "@opentelemetry/core": "2.0.1",
    "@opentelemetry/exporter-trace-otlp-http": "0.201.1",
    "@opentelemetry/instrumentation-fetch": "0.201.1",
    "@opentelemetry/instrumentation-xml-http-request": "0.201.1",
    "@opentelemetry/otlp-exporter-base": "0.201.1",
    "@opentelemetry/resources": "2.0.1",
    "@opentelemetry/sdk-trace-base": "2.0.1",
    "@opentelemetry/sdk-trace-web": "2.0.1",
    "@opentelemetry/semantic-conventions": "1.33.1",
    "@tanstack/react-query": "^5.59.16",
    "date-fns": "4.1.0",
    "graphql": "^16.10.0",
    "i18next": "24.2.1",
    "lodash": "^4.17.21",
    "react-i18next": "15.4.0",
    "react-native-device-info": "14.0.4",
    "react-native-render-html": "6.3.4",
    "react-native-url-polyfill": "2.0.0",
    "sanitize-html": "2.17.0",
    "zod": "^3.23.8",
    "zustand": "^5.0.3",
    "zx": "^8.4.0"
  }

//  App/Framework package dependencies

"dependencies": {
    "@lodev09/react-native-true-sheet": "*",
    "@react-native-masked-view/masked-view": "*",
    "@react-navigation/native": "*",
    "@react-navigation/native-stack": "*",
    "@zest/react-native": "*",
    "react": "*",
    "react-native": "*",
    "react-native-device-info": "*",
    "react-native-nitro-modules": "*",
    "react-native-pager-view": "*",
    "react-native-reanimated": "*",
    "react-native-restart": "*",
    "react-native-safe-area-context": "*",
    "react-native-screens": "*",
    "react-native-svg": "*"
  },
  "devDependencies": {
    "@babel/core": "^7.20.0",
    "@babel/preset-env": "^7.20.0",
    "@babel/runtime": "^7.20.0",
    "@react-native/babel-preset": "0.75.4",
    "@react-native/metro-config": "0.75.4",
    "@react-native/typescript-config": "0.75.4",
    "react-native-builder-bob": "^0.30.2"
  }

Nitro Modules Version

^0.26.2

Nitrogen Version

^0.26.2

Target platforms

iOS

Operating system

MacOS

Can you build the Nitro Modules Example app?

No, I cannot build the Example app either

I tried running in the example app, but ran into issues with React Codegen failing. I spent too much time on trying to get the example app also working.

Additional information

• I am using Expo
• I am using Nitrogen (nitro-codegen)
• I have read and followed the Troubleshooting Guide.
• I created a reproduction PR to reproduce this issue here in the nitro repo. (See Contributing for more information)
• I searched for similar issues in this repository and found none.

[mrousavy]

Hm I'm not sure if I understand the problem properly.

Is there any way for you to separate your SPM part from the Nitro Module? I'm pretty sure it's the new C++ interop in the Swift Compiler that's kinda spazzing out with the stuff you added to it.
Separating it into two frameworks will fix that

[serjooo]

Thanks for checking this out @mrousavy. That is the setup we have. We added a local podspec for the Nitro module. Once we execute pod install, we obtain the NitroModule as an external dependency / Framework, which we then link or import into our SPM framework.

---

It seemed the problem was related to the following issue.

Adding the following in our local podspec fixed the compilation issues in NitroExternalNativeModules:

s.pod_target_xcconfig = {
  "HEADER_SEARCH_PATHS" => [
    "${PODS_ROOT}/RCT-Folly",
  ],
  "GCC_PREPROCESSOR_DEFINITIONS" => "$(inherited) FOLLY_NO_CONFIG FOLLY_CFG_NO_COROUTINES",
  "OTHER_CPLUSPLUSFLAGS" => "-DFOLLY_NO_CONFIG -DFOLLY_MOBILE=1 -DFOLLY_USE_LIBCPP=1",
}

[serjooo]

Unfortunately, it seems like after fixing other setup issues and compilation issues, the main XCFranework / Target is having issues with Folly

I added the GCC_PREPROCESSOR_DEFINITIONS and OTHER_CPLUSPLUSFLAGS in our XCFramework / SPM.

I also added the following to the podspec, which seems the Lottie-react-native package had a similar issue as well

  s.requires_arc = true
  s.dependency "React-Core"

It got rid of the Folly and React errors,.

Now I'm getting a build log issue that the generated code/symbol is duplicated:

duplicate symbol 'protocol witness for Cxx.CxxPair.first.modify : A.First in conformance __C.std.__1.pair<std.__1.basic_string<CChar, std.__1.char_traits<CChar>, std.__1.allocator<CChar>>_const, std.__1.variant<std.__1.basic_string<CChar, std.__1.char_traits<CChar>, std.__1.allocator<CChar>>, CDouble, CBool>> : Cxx.CxxPair in __C_Synthesized' in:
    /Users/serjagopian/Library/Developer/Xcode/DerivedData/SharedMobileModules-bqqdssxheojywccubsqrrqwdvfye/Build/Products/Debug-iphonesimulator/NitroExternalNativeModules/NitroExternalNativeModules.framework/NitroExternalNativeModules[15](OpenScreenEvent.o)
    /Users/serjagopian/Library/Developer/Xcode/DerivedData/SharedMobileModules-bqqdssxheojywccubsqrrqwdvfye/Build/Products/Debug-iphonesimulator/NitroExternalNativeModules/NitroExternalNativeModules.framework/NitroExternalNativeModules[8](AnalyticsEvent.o)
duplicate symbol 'protocol witness for Cxx.CxxPair.first.setter : A.First in conformance __C.std.__1.pair<std.__1.basic_string<CChar, std.__1.char_traits<CChar>, std.__1.allocator<CChar>>_const, std.__1.variant<std.__1.basic_string<CChar, std.__1.char_traits<CChar>, std.__1.allocator<CChar>>, CDouble, CBool>> : Cxx.CxxPair in __C_Synthesized' in:
    /Users/serjagopian/Library/Developer/Xcode/DerivedData/SharedMobileModules-bqqdssxheojywccubsqrrqwdvfye/Build/Products/Debug-iphonesimulator/NitroExternalNativeModules/NitroExternalNativeModules.framework/NitroExternalNativeModules[15](OpenScreenEvent.o)
    /Users/serjagopian/Library/Developer/Xcode/DerivedData/SharedMobileModules-bqqdssxheojywccubsqrrqwdvfye/Build/Products/Debug-iphonesimulator/NitroExternalNativeModules/NitroExternalNativeModules.framework/NitroExternalNativeModules[8](AnalyticsEvent.o)
ld: 2 duplicate symbols
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I suspect this might have to do that we build our pods as static libraries instead of dynamic. I will try to exclusively build the NitroExternalNativeModules as a dynamic library.

[serjooo]

@mrousavy by the way, I noticed while using npx create-react-native-library@latest, the podspec file doesn't have the same template as you have here. Specifically it is missing the following:

  s.source_files = [
    # Implementation (Swift)
    "ios/**/*.{swift}",
    # Autolinking/Registration (Objective-C++)
    "ios/**/*.{m,mm}",
    # Implementation (C++ objects)
    "cpp/**/*.{hpp,cpp}",
  ]

  s.pod_target_xcconfig = {
    # C++ compiler flags, mainly for folly.
    "GCC_PREPROCESSOR_DEFINITIONS" => "$(inherited) FOLLY_NO_CONFIG FOLLY_CFG_NO_COROUTINES"
  }

  s.dependency 'React-jsi'
  s.dependency 'React-callinvoker'

This is the template you get ouside the box with the CLI:

require "json"

package = JSON.parse(File.read(File.join(__dir__, "package.json")))

Pod::Spec.new do |s|
  s.name         = "NitroLibrary"
  s.version      = package["version"]
  s.summary      = package["description"]
  s.homepage     = package["homepage"]
  s.license      = package["license"]
  s.authors      = package["author"]

  s.platforms    = { :ios => min_ios_version_supported }
  s.source       = { :git => "https://github.com/serjooo/nitro-module-example.git.git", :tag => "#{s.version}" }

  s.source_files = "ios/**/*.{h,m,mm,swift}"

  load 'nitrogen/generated/ios/NitroLibrary+autolinking.rb'
  add_nitrogen_files(s)

  install_modules_dependencies(s)
end

[mrousavy]

Oh well I guess then we need to add that to the template - can you create a PR in create-react-native-libray? thanks

[serjooo]

@mrousavy already done ✅. I was wondering if we should have a smarter process to keep both templates in sync. It's not ideal that we have two sources of truth for the template. One idea I have is that the other tool pulls the template folder from this repository while genearting a nitro-module library.

---

By the way, I'm still facing some compilation issues. I haven't had the time to debug further, but I'm hoping to be able to reproduce it in a controlled smaller project. I'll keep this thread updated once I get back to it.

[mrousavy]

By the way, I'm still facing some compilation issues. I haven't had the time to debug further, but I'm hoping to be able to reproduce it in a controlled smaller project. I'll keep this thread updated once I get back to it.

Thank you! Sorry I can't be of better help - but I cannot reproduce this and I honestly don't have a lot of free time now... so if you find a solution to this, this would be hugely appreciated.

[mrousavy]

does this fix anything? #702

[mrousavy]

nvm I think we don't want library evolution. Swift's C++ interop does not seem to support it for types imported from C++, so we need to disable it. It's disabled by default, maybe you switched it on?

[serjooo]

Hey @mrousavy, thanks for checking that out. I probably did enable it because we plan to distribute the Brownfield library integration, but it might work without it being turned on as well. I'm currently focused on another topic and have deprioritized this. Also, no ETA when I'll be able to check it out again given some personal life changes. However, definitely we will need to have this done sooner or later, so I will follow up on the issue and try to debug further.

[mrousavy]

Note, this might be related to https://forums.swift.org/t/error-when-cross-compiling-swift-package-with-cxx-interop-enabled-with-swift-6-2/81330