Raspberry Pi 4 B g++ undefined reference to boost::system::system_category()

Question

I created a simple program in C++ on my RPi to test the Boost library. This is the code:

#include <iostream>
#include <boost/asio.hpp>

int main()
{
    std::cout << "Hello World!" << std::endl;
    std::cout << "Opening TCP socket on port 9999..." << std::endl;
    boost::asio::io_context io_context;
    boost::asio::ip::tcp::endpoint endpoint(boost::asio::ip::tcp::v4(), 9999);
    io_context.run();
    std::cout << "Socket opened!" << std::endl;
    io_context.stop();
    st::cout << "Socket closed." << std::endl;
    return 0;
}

And this is the compile command:

g++ -lpthread -lboost_system main.cpp -o test

But when I try to compile the program I get this error:

/usr/bin/ld: /tmp/ccGWgmo2.o: in function `boost::system::error_code::error_code()':
main.cpp:(.text._ZN5boost6system10error_codeC2Ev[_ZN5boost6system10error_codeC5Ev]+0x1c): undefined reference to `boost::system::system_category()'
/usr/bin/ld: /tmp/ccGWgmo2.o: in function `boost::system::error_category::std_category::equivalent(int, std::error_condition const&) const':
main.cpp:(.text._ZNK5boost6system14error_category12std_category10equivalentEiRKSt15error_condition[_ZNK5boost6system14error_category12std_category10equivalentEiRKSt15error_condition]+0xcc): undefined reference to `boost::system::generic_category()'
/usr/bin/ld: main.cpp:(.text._ZNK5boost6system14error_category12std_category10equivalentEiRKSt15error_condition[_ZNK5boost6system14error_category12std_category10equivalentEiRKSt15error_condition]+0x118): undefined reference to `boost::system::generic_category()'
/usr/bin/ld: /tmp/ccGWgmo2.o: in function `boost::system::error_category::std_category::equivalent(std::error_code const&, int) const':
main.cpp:(.text._ZNK5boost6system14error_category12std_category10equivalentERKSt10error_codei[_ZNK5boost6system14error_category12std_category10equivalentERKSt10error_codei]+0xcc): undefined reference to `boost::system::generic_category()'
/usr/bin/ld: main.cpp:(.text._ZNK5boost6system14error_category12std_category10equivalentERKSt10error_codei[_ZNK5boost6system14error_category12std_category10equivalentERKSt10error_codei]+0x118): undefined reference to `boost::system::generic_category()'
/usr/bin/ld: main.cpp:(.text._ZNK5boost6system14error_category12std_category10equivalentERKSt10error_codei[_ZNK5boost6system14error_category12std_category10equivalentERKSt10error_codei]+0x1fc): undefined reference to `boost::system::generic_category()'
/usr/bin/ld: /tmp/ccGWgmo2.o: in function `boost::asio::error::get_system_category()':
main.cpp:(.text._ZN5boost4asio5error19get_system_categoryEv[_ZN5boost4asio5error19get_system_categoryEv]+0x8): undefined reference to `boost::system::system_category()'
collect2: error: ld returned 1 exit status

I installed Boost using this command:

sudo apt install libboost-dev

How do I go around working out why this won't compile?

P.S: I added -lpthread because I was getting errors about pthread, and I added -lboost_system because I already did research on the errors (which used to be a much larger paragraph) and it got rid of most of them.

I am running g++ (Raspbian 8.3.0-6+rpil) 8.3.0 on the Raspberry Pi 4 B (4GB).

I'd strongly recommend using CMake to build your applications. Manually keeping track of dependencies and making sure they are in the correct order does not scale.
In CMake, you can simply say find_package(Boost ...) and target_link_libraries(my-app PRIVATE Boost::system). — tttapa, Jan 07 '20 at 14:40
st::cout << "Socket closed." << std::endl; you have an error here ; std — Ephemeral, Jan 07 '20 at 14:53

Ephemeral · Accepted Answer · 2020-01-07T16:45:33.750

1

Install (where XX is the last version : sudo apt-cache search libboost-system1):

sudo apt-get install libboost-dev libboost-system1.XX-dev libboost-system1.XX libasio-dev

C++

#include <iostream>
#include <boost/array.hpp>
#include <boost/asio.hpp>    

int main(){

    std::cout << "Hello World!" << std::endl;
    std::cout << "Opening TCP socket on port 9999..." << std::endl;
    // > 1.66
    boost::asio::io_context io_context;
    // < 1.66
    //io_service io_service;

    boost::asio::ip::tcp::endpoint endpoint(boost::asio::ip::tcp::v4(), 9999);
    boost::asio::io_context.run();
    std::cout << "Socket opened!" << std::endl;
    boost::asio::io_context.stop();
    std::cout << "Socket closed." << std::endl;
    return 0;
}

Older g++:

g++ -lboost_system -lpthread -o test test.cpp

New g++ :

g++ -o test -lboost_system -lpthread test.cpp

Now you can use the lib.

edited Jan 07 '20 at 16:45

answered Jan 07 '20 at 14:59

Ephemeral

2,157
1
6
19

What does this have to do with namespaces though? I don't think bringing the entire boost namespace in is an improvement. – tttapa Jan 07 '20 at 16:28
@tttapa I don't understand your opinion – Ephemeral Jan 07 '20 at 16:30
1

Using entire namespaces is bad practice, boost and std share many names, so it could lead to problems in the future, but most of all, it is not at all related to the original question. – tttapa Jan 07 '20 at 16:34
@tttapa, yes but the question is not about programming but about compilation ... I may be expressing myself badly sorry. I put this as an example – Ephemeral Jan 07 '20 at 16:36
Should I be using using namespace to simplify the references to Boost as good practice? – Logan Jan 07 '20 at 20:17
@Logan, read the link provided by tttpaa above. – Ephemeral Jan 08 '20 at 19:38

tttapa · Answer 2 · 2020-01-07T16:01:32.157

1

The problem is the order of linking. You have to compile your code first (or specify your object files first), and then specify the libraries you want to link to.

g++ main.cpp -lboost_system -o test

Using this command, and after fixing a small bug in your code (st::cout → std::cout), everything compiles and links correctly.

You can simplify the build process by using CMake.

Create a CMakeLists.txt file in your project folder, and add the contents below
Create a build directory and run CMake in that directory: mkdir build && cd build && cmake ..
Build the project by typing make

cmake_minimum_required(VERSION 3.10)
project(test)

find_package(Boost REQUIRED COMPONENTS system) # asio is part of Boost::system

add_executable(test main.cpp)
target_link_libraries(test Boost::system)

edited Jan 07 '20 at 16:01

answered Jan 07 '20 at 15:56

tttapa

986
5
7

I think the error of the question is : libboost-system1.XX is missing and not installed. asio require boost::system. The order (see my answer) not do anything. – Ephemeral Jan 07 '20 at 16:04
@Ephemeral: if libboost-system is missing, the linker throws a different error: /usr/bin/ld: cannot find -lboost_system. Order matters when linking libraries. – tttapa Jan 07 '20 at 16:07
I have resolve the same issue with installing libboost-system1.XX-dev, sorry not the library. – Ephemeral Jan 07 '20 at 16:09
@Ephemeral: I just tried it again, with GCC 5.5.0, GCC 6.5.0, GCC 7.4.0, GCC 8.3.0 and GCC 9.2.1 on Ubuntu 16.04. g++ -lboost_system -lpthread -o test test.cpp results in the linker errors of OP, g++ test.cpp -lboost_system -o test works fine. What compiler version and OS are you testing this on? – tttapa Jan 07 '20 at 16:12
With an old version... yes finally you are probably rigth. But libboost-system1.XX-dev is require in all cases I suppose. User do only sudo apt install libboost-dev and use -lboost_system, the the headers library files must be installed. – Ephemeral Jan 07 '20 at 16:23
Doing sudo apt install libboost-system-dev worked. – Logan Jan 07 '20 at 20:14
@Logan Does the order of linking matter on your system? – tttapa Jan 07 '20 at 20:21
I didn't need to modify the g++ command, no. – Logan Jan 07 '20 at 20:23
@Logan: it seems to work on some distributions and compiler versions. In general, this is not the case, and it would be safer to fix the order: https://stackoverflow.com/questions/45135/why-does-the-order-in-which-libraries-are-linked-sometimes-cause-errors-in-gcc – tttapa Jan 07 '20 at 20:31

Raspberry Pi 4 B g++ undefined reference to boost::system::system_category()

2 Answers2