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Fantom's tester does not build with Clang 23: nlohmann_json 3.11.2 trips -Wdeprecated-literal-operator under -Werror #59667
Description
Description
Fantom's tester does not build with a current Clang. React Native pins nlohmann_json 3.11.2 (packages/react-native/gradle/libs.versions.toml), whose json.hpp declares its literal operators with a space before the suffix, operator "" _json and operator "" _json_pointer. Clang 23 reports that form under -Wdeprecated-literal-operator, and the tester builds with -Werror, so yarn workspace @react-native/fantom build stops in json.hpp. Fantom's CI job builds with the apt Clang of its Ubuntu 22.04 image, so it does not see this.
nlohmann_json 3.12.0 drops the space (operator""_json), and the tester builds with it.
Steps to reproduce
git clone https://github.com/YevheniiKotyrlo/react-native-fantom-reproducer && cd react-native-fantom-reproducer./fantom/reproduce.sh build(needs Docker). It builds the image infantom/Dockerfile, which is React Native's Fantom CI image with Clang and LLD from LLVM 23.1.3 in place of the apt Clang, clonesreact/react-nativeatmain, runsyarn install, and runs Fantom's CI build,yarn workspace @react-native/fantom build.
The same on a checkout of main, in that image: CC=clang CXX=clang++ LDFLAGS=-fuse-ld=lld yarn workspace @react-native/fantom build. buildFantomTester fails, and Gradle keeps the compiler's errors in private/react-native-fantom/build/reports/.
React Native Version
0.88.0 (reproduced on main at 54905a2)
Affected Platforms
Build - Linux
Output of npx @react-native-community/cli info
System:
OS: Linux 6.18 Ubuntu 22.04.5 LTS 22.04.5 LTS (Jammy Jellyfish)
CPU: (24) x64 AMD Ryzen 9 9950X3D 16-Core Processor
Memory: 116.43 GB / 125.63 GB
Shell:
version: 5.1.16
path: /bin/bash
Binaries:
Node:
version: 22.14.0
path: /usr/local/bin/node
Yarn:
version: 1.22.22
path: /usr/local/bin/yarn
npm:
version: 10.9.2
path: /usr/local/bin/npm
Watchman: Not Found
SDKs:
Android SDK:
API Levels:
- "37"
Build Tools:
- 37.0.0
Android NDK: 28.2.13676358
IDEs:
Android Studio: Not Found
Languages:
Java:
version: 17.0.20.1
path: /usr/bin/javac
Ruby:
version: 3.0.2
path: /usr/bin/ruby
npmPackages:
"@react-native-community/cli": Not Found
react: Not Found
react-native: Not Found
npmGlobalPackages:
"*react-native*": Not Found
Android:
hermesEnabled: Not found
newArchEnabled: Not found
iOS:
hermesEnabled: Not found
newArchEnabled: Not found
Stacktrace or Logs
/react-native/private/react-native-fantom/build/third-party/nlohmann_json/include/nlohmann/json.hpp:5136:35: error: identifier '_json' preceded by whitespace in a literal operator declaration is deprecated [-Werror,-Wdeprecated-literal-operator]
/react-native/private/react-native-fantom/build/third-party/nlohmann_json/include/nlohmann/json.hpp:5144:49: error: identifier '_json_pointer' preceded by whitespace in a literal operator declaration is deprecated [-Werror,-Wdeprecated-literal-operator]
/react-native/private/react-native-fantom/build/third-party/nlohmann_json/include/nlohmann/json.hpp:5208:58: error: identifier '_json' preceded by whitespace in a literal operator declaration is deprecated [-Werror,-Wdeprecated-literal-operator]
/react-native/private/react-native-fantom/build/third-party/nlohmann_json/include/nlohmann/json.hpp:5209:58: error: identifier '_json_pointer' preceded by whitespace in a literal operator declaration is deprecated [-Werror,-Wdeprecated-literal-operator]
MANDATORY Reproducer
https://github.com/YevheniiKotyrlo/react-native-fantom-reproducer
Screenshots and Videos
No response
Activity