I'm trying to compile the following MWE that uses jsoncpp installed from Conan and set up with cmake, using g++-12 (from home-brew) but I'm clashing against all types of linking errors. (adding repo so its easier to run the MWE https://github.com/araml/link_error)
main.cpp.
#include <cstdio>
#include <fstream>
#include <json/json.h>
int main() {
std::ifstream j1_json("j1");
Json::Value j1;
Json::Reader parser;
if (!parser.parse(j1_json, j1)) {
puts("Error when parsing j1");
}
return 0;
}
cmake
cmake_minimum_required(VERSION 3.16)
project(j1_test)
enable_testing()
set(CMAKE_CXX_FLAGS "-std=c++2a -ggdb -Wall -Wextra -Og -fno-inline-functions")
set(CMAKE_C_COMPILER "gcc-12") # I know not the best but easier here for the examples purpose
set(CMAKE_CXX_COMPILER "g++-12")
find_package(jsoncpp CONFIG REQUIRED)
add_executable(j1 src/main.cpp)
target_link_libraries(j1 JsonCpp::JsonCpp)
conanfile.txt
[requires]
jsoncpp/1.9.5
[generators]
CMakeDeps
CMakeToolchain
What I'm running
conan install conanfile.txt --install-folder conan --build=missing -pr:b=default
mkdir -p build
push build
cmake -DCMAKE_TOOLCHAIN_FILE=./conan/conan_toolchain.cmake -DCMAKE_BUILD_TYPE=Release -G Ninja ../
cmake --build . -j 8
popd
error output (partial)
[2/2] Linking CXX executable j1
FAILED: j1
: && g++-12 -std=c++2a -ggdb -Wall -Wextra -Og -fno-inline-functions -O3 -DNDEBUG -arch arm64 -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -Wl,-search_paths_first -Wl,-headerpad_max_install_names CMakeFiles/j1.dir/src/main.cpp.o -o j1 /Users/meera/.conan/data/jsoncpp/1.9.5/_/_/package/2f2de4e3345f667bb03ed16a03f45c72c978d397/lib/libjsoncpp.a && :
Undefined symbols for architecture arm64:
"__ZN4Json6Reader5parseERSiRNS_5ValueEb", referenced from:
_main in main.cpp.o
"__ZNKSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE4findEcm", referenced from:
__ZN4Json12_GLOBAL__N_113valueToStringEdbjNS_13PrecisionTypeE in libjsoncpp.a(json_writer.cpp.o)
"__ZNKSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE7compareEmmPKcm", referenced from:
__ZNK4Json19StreamWriterBuilder15newStreamWriterEv in libjsoncpp.a(json_writer.cpp.o)
"__ZNKSt3__115basic_stringbufIcNS_11char_traitsIcEENS_9allocatorIcEEE3strEv", referenced from:
__ZN4Json5ValueC2EPKc in libjsoncpp.a(json_value.cpp.o)
__ZN4JsonL29duplicateAndPrefixStringValueEPKcj in libjsoncpp.a(json_value.cpp.o)
__ZNK4Json5Value9asCStringEv in libjsoncpp.a(json_value.cpp.o)
__ZNK4Json5Value8asStringEv in libjsoncpp.a(json_value.cpp.o)
__ZNK4Json5Value5asIntEv in libjsoncpp.a(json_value.cpp.o)
__ZNK4Json5Value6asUIntEv in libjsoncpp.a(json_value.cpp.o)
__ZNK4Json5Value7asInt64Ev in libjsoncpp.a(json_value.cpp.o)
If I set libc++, -lc++
, I get a different type of error
-- Using Conan toolchain: jsoncpp_test/conan/conan_toolchain.cmake
-- Conan: Target declared 'JsonCpp::JsonCpp'
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/meera/Projects/jsoncpp_test/build
[2/2] Linking CXX executable j1
FAILED: j1
: && g++-12 -std=c++2a -ggdb -Wall -Wextra -lc++ -Og -fno-inline-functions -O3 -DNDEBUG -arch arm64 -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -Wl,-search_paths_first -Wl,-headerpad_max_install_names CMakeFiles/j1.dir/src/main.cpp.o -o j1 /Users/meera/.conan/data/jsoncpp/1.9.5/_/_/package/2f2de4e3345f667bb03ed16a03f45c72c978d397/lib/libjsoncpp.a && :
Undefined symbols for architecture arm64:
"__ZN4Json6Reader5parseERSiRNS_5ValueEb", referenced from:
_main in main.cpp.o
ld: symbol(s) not found for architecture arm64
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.
~/Projects/jsoncpp_test
Compiling with apple-clang works just fine but I need to use g++-12 since clang doesn't support some of the features I want to use.
I fixed this by creating a conan profile
conan profile new --detect build
Changing
compiler=apple-clang
compiler.version=15
into
compiler=gcc
compiler.version=12
And then adding
[conf]
tools.build:compiler_executables={"c": "gcc-12", "cpp": "g++-12"}
Finally you can run conan with
-pr=build
so it picks up the profile and compiles the packages with g++.