Undefined symbols (link error) when using libpqxx

Question

I can't seem to link libpqxx.

The program:

#include <pqxx/pqxx>
int main()
    pqxx::connection connection(""); 
    return 0;
}

The command to compile:

g++ -std=c++23 -arch arm64 x.cc -lpqxx -lpq -I/usr/local/include -L/usr/local/libc-L/opt/homebrew/opt/libpq/lib -I/opt/homebrew/opt/libpq/include

I'm on macOS Sequoia 15.3.1

I've tried this many ways:

1. brew install libpqxx and use those includes and libraries in the compilation command
2. built libpqxx myself (in usr/local/, which is what you can see in the command)
3. I've also tried with cmake: a) fetch_content, b) with pkg-config, c) with the homebrew installation

It just does not build. This is usually the error I get:

Undefined symbols for architecture arm64:
  "pqxx::argument_error::argument_error(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&)", referenced from:
      pqxx::internal::(anonymous namespace)::throw_for_encoding_error(char const*, char const*, unsigned long, unsigned long) in ccBebBm9.o
  "pqxx::internal::demangle_type_name[abi:cxx11](char const*)", referenced from:
      __static_initialization_and_destruction_0() in ccBebBm9.o
      __static_initialization_and_destruction_0() in ccBebBm9.o
      __static_initialization_and_destruction_0() in ccBebBm9.o
      __static_initialization_and_destruction_0() in ccBebBm9.o
ld: symbol(s) not found for architecture arm64
collect2: error: ld returned 1 exit status

Answer 1

I've also tried with cmake: a) fetch_content

Just test tried it out with fetch content and its working fine for me

Given that you have pkg-config and libpq installed and findable, i.e. with brew.

Then the following should work with the given structure

~/cpp-sandbox
├── CMakeLists.txt
└── src
    └── main.cpp

CMakeLists.txt

cmake_minimum_required(VERSION 3.22)
project(cpp_sandbox)
set(CMAKE_CXX_STANDARD 23)

include(FetchContent)

FetchContent_Declare(
        libpqxx
        GIT_REPOSITORY https://github.com/jtv/libpqxx.git
        GIT_TAG        7.10.0
)

FetchContent_MakeAvailable(libpqxx)

add_executable(${PROJECT_NAME} src/main.cpp)
target_link_libraries(${PROJECT_NAME} PRIVATE pqxx)

src/main.cpp

#include <pqxx/pqxx>

int main() {
    pqxx::connection connection(""); 
    return 0;
}

building with

cmake -DCMAKE_PREFIX_PATH="/opt/homebrew/opt/libpq"
cmake -build .