Could NOT find Boost (missing: system) (found suitable versiHow on "1.78.0", minimum required is "1.78.0")

Question

How to run boost asio with cmake? Havint this simple project layout:

c1
├── c1
│   └── main.cpp
└── CMakeLists.txt

CMakeLists.txt:

cmake_minimum_required(VERSION 3.20.0)
project(c1)

add_executable(c1 c1/main.cpp)
include_directories(.)

set(BOOST_ROOT /usr/local/boost_1_78_0)
find_package(Boost 1.78.0 REQUIRED COMPONENTS system)
target_include_directories(c1 PUBLIC ${Boost_INCLUDE_DIR})
target_link_libraries(c1 LINK_PUBLIC ${Boost_LIBRARIES})

and main.cpp:

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

int main(){
    boost::asio::io_context io;
    boost::asio::steady_timer t(io, boost::asio::chrono::seconds(5));
    t.wait();
    std::cout << "Hello world!" << std::endl;
}

I am getting this cmake error:

CMake Error at /usr/local/share/cmake-3.22/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
  Could NOT find Boost (missing: system) (found suitable version "1.78.0",
  minimum required is "1.78.0")
Call Stack (most recent call first):
  /usr/local/share/cmake-3.22/Modules/FindPackageHandleStandardArgs.cmake:594 (_FPHSA_FAILURE_MESSAGE)
  /usr/local/share/cmake-3.22/Modules/FindBoost.cmake:2360 (find_package_handle_standard_args)
  CMakeLists.txt:8 (find_package)

I am not sure if I understand it correclty, but it is trying to find suitable version 1.78.0, but it found 1.78.0, so what is the problem?

Also before that, there was a warning:

CMake Warning at /usr/local/share/cmake-3.22/Modules/FindBoost.cmake:1369 (message):
  New Boost version may have incorrect or missing dependencies and imported
  targets
Call Stack (most recent call first):
  /usr/local/share/cmake-3.22/Modules/FindBoost.cmake:1492 (_Boost_COMPONENT_DEPENDENCIES)
  /usr/local/share/cmake-3.22/Modules/FindBoost.cmake:2102 (_Boost_MISSING_DEPENDENCIES)
  CMakeLists.txt:8 (find_package)

So what should I do?

EDIT: the system library is at:

/usr/local/boost_1_78_0/boost/system

and the debug output of where is cmake looking:

-- [ /usr/local/share/cmake-3.22/Modules/FindBoost.cmake:2053 ] _boost_LIBRARY_SEARCH_DIRS_RELEASE = "/usr/local/boost_1_78_0/lib;/usr/local/boost_1_78_0/stage/lib;/usr/local/boost_1_78_0/lib;/usr/local/boost_1_78_0/../lib;/usr/local/boost_1_78_0/stage/lib;PATHS;C:/boost/lib;C:/boost;/sw/local/lib"
-- [ /usr/local/share/cmake-3.22/Modules/FindBoost.cmake:2054 ] _boost_LIBRARY_SEARCH_DIRS_DEBUG = "/usr/local/boost_1_78_0/lib;/usr/local/boost_1_78_0/stage/lib;/usr/local/boost_1_78_0/lib;/usr/local/boost_1_78_0/../lib;/usr/local/boost_1_78_0/stage/lib;PATHS;C:/boost/lib;C:/boost;/sw/local/lib"

-- [ /usr/local/share/cmake-3.22/Modules/FindBoost.cmake:2239 ] Searching for SYSTEM_LIBRARY_RELEASE: boost_system-gcc10-mt-1_78;boost_system-gcc10-mt;boost_system-gcc10-mt;boost_system-mt-1_78;boost_system-mt;boost_system-mt;boost_system-mt;boost_system
-- [ /usr/local/share/cmake-3.22/Modules/FindBoost.cmake:2294 ] Searching for SYSTEM_LIBRARY_DEBUG: boost_system-gcc10-mt-d-1_78;boost_system-gcc10-mt-d;boost_system-gcc10-mt-d;boost_system-mt-d-1_78;boost_system-mt-d;boost_system-mt-d;boost_system-mt;boost_system

Yet I cannot understand, why the cmake cannot find that library.

Answer 1

Looks like you forgot to build the Boost libraries.

Many Boost libraries are, or can be, header-only, but many aren't.

I think the CMake FindBoost components only bother with the libraries that require building. So, if you name system as a required component, you're telling CMake that you need to link it, and it looks for the built libraries.

The built libraries are typically under stage/lib/ e.g.

/home/sehe/custom/boost/stage/lib/libboost_system.a
/home/sehe/custom/boost/stage/lib/libboost_system.so
/home/sehe/custom/boost/stage/lib/libboost_system.so.1.78.0

However, if you didn't build the library, it will be missing.

See https://www.boost.org/doc/libs/1_78_0/more/getting_started/unix-variants.html

Answer 2

Don't waste your time trying to compile Boost, this is not the problem here.

Like Tsyvarev said, since version 1.69 if you are using only system or any other header-only component (not requiring build) you must remove keyword COMPONENT

find_package(Boost 1.80.0 REQUIRED)

# ...Nothing more