Howto use cmake with boost asio?

Question

I cannot get boost::asio to work with cmake in my c++ program. I have actually tried and googled for many hours, but I cannot get it to work!

I want to include boost::asio in my c++ Project under Ubuntu 18.04 with a cmake file.

So I installed the newest CMake (cmake version 3.19.4), and I downloaded boost version 1.74 and executed

./bootstrap.sh --prefix=/usr/
sudo ./b2 install

The install directory is /home/boost/boost_1_74_0. My CMake file looks like this:

cmake_minimum_required (VERSION 3.1.0)
# Project name
project (machine_tryout VERSION 1.0)

# Boost (header only)
#set(Boost_DEBUG 1)
set(BOOST_ROOT "$ENV{HOME}/boost/boost_1_74_0")
set(Boost_INCLUDE_DIR  "$ENV{HOME}/boost/boost_1_74_0")
set(Boost_LIBRARY_DIR "$ENV{HOME}/boost/boost_1_74_0/libs")
find_package(Boost REQUIRED Components asio) 
    
# Set Executable
add_executable(${PROJECT_NAME} source/tryout.cpp)

But everything I get is the following:

vm-umic@vm:~/Projects/tryout/build$ cmake ..
CMake Warning at /snap/cmake/775/share/cmake-3.19/Modules/FindBoost.cmake:2034 (message):
  No header defined for asio; skipping header check (note: header-only
  libraries have no designated component)
Call Stack (most recent call first):
  CMakeLists.txt:27 (find_package)


CMake Error at /snap/cmake/775/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:218 (message):
  Could NOT find Boost (missing: asio) (found version "1.74.0")
Call Stack (most recent call first):
  /snap/cmake/775/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:582 (_FPHSA_FAILURE_MESSAGE)
  /snap/cmake/775/share/cmake-3.19/Modules/FindBoost.cmake:2193 (find_package_handle_standard_args)
  CMakeLists.txt:27 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/vm-umic/Projects/tryout/build/CMakeFiles/CMakeOutput.log".

What in the world am I doing wrong? Isnt CMake telling me that it found Boost 1.74? CMake does NOT throw any errors if I try find_package(Boost REQUIRED), but then linking does also not work. I explicitly tell CMake where to find the libraries, so why can't CMake finde Boost?

If the linking does not work then the linker error message would be helpful for everybody to assist you. — Jorge Bellon, Feb 02 '21 at 09:00
Does this answer your question? [Using boost.asio in cMake](https://stackoverflow.com/questions/2078898/using-boost-asio-in-cmake) — Paul Varghese, Feb 02 '21 at 09:41

score 2 · Answer 1 · answered Feb 01 '21 at 23:03

2

Try this.

cmake_minimum_required (VERSION 3.1.0)
# Project name
project (machine_tryout VERSION 1.0)

# Boost (header only)
#set(Boost_DEBUG 1)
set(BOOST_ROOT "$ENV{HOME}/boost/boost_1_74_0")
set(Boost_INCLUDE_DIR  "$ENV{HOME}/boost/boost_1_74_0")
set(Boost_LIBRARY_DIR "$ENV{HOME}/boost/boost_1_74_0/libs")
find_package(Boost REQUIRED Components system) 
    
# Set Executable
add_executable(${PROJECT_NAME} source/tryout.cpp)
target_link_libraries(${PROJECT_NAME}
    ${Boost_LIBRARIES})

answered Feb 01 '21 at 23:03

Paul Varghese

1,635
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9

Code-only answers aren’t nice. Please explain *why* this fixes the problem. – Kuba hasn't forgotten Monica Feb 02 '21 at 02:43
I tried this, unfortunately this does not work as intended, it tells me: `CMake Error at /snap/cmake/775/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:218 (message): Could NOT find Boost (missing: Components system) (found version "1.74.0")` Perhaps I did not correctly install boost? How can it find boost but not this library? – U_flow Feb 02 '21 at 08:12
2

To answer @Kubahasn'tforgottenMonica 's comment, it should work because although `boost asio` is header only, it depends on `boost system` for error handling so it links to the `boost system` binary. @U_flow it sounds like you haven't built `boost`. You can build it by following the instructions here: https://www.boost.org/doc/libs/1_75_0/more/getting_started/unix-variants.html or even easier by just installing it, see: https://stackoverflow.com/questions/12578499/how-to-install-boost-on-ubuntu. Note, Ubuntu is likely to install an older version than 1.74 or 1.75 (the latest). – kenba Feb 02 '21 at 08:34
2

The case of `find_package` keyword `COMPONENTS` matters here. The error message lists `Components` as missing library. – vre Feb 02 '21 at 08:58
Btw, you are missing a call to `target_include_directories(${PROJECT_NAME} PRIVATE ${Boost_INCLUDE_DIRS})` – vre Feb 02 '21 at 09:13
@kenba perhaps you are right and I havent't (successfully) built boost! I just reread the documentation on building and the "lib" folder should be built (although I have a "libs" (with an s) folder). I have not used apt-get install, because it threw me a bunch of "uninstalled dependencies errors" so I thought it would be easier to install directly from source, but I guess some of the dependencies are needed... – U_flow Feb 02 '21 at 16:28

score 1 · Answer 2 · answered Sep 16 '22 at 17:54

I just had a similar problem, and found that I had missed a small but important step in the Boost installation: adding the installation directory (i.e. the PREFIX used in b2 install --prefix=PREFIX) to the PATH environment variable.

For me, this solved it – hopefully will for you too!

Howto use cmake with boost asio?

2 Answers2

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