Hunter prevents using dependencies installed system-wide

[xzxzzxzxzca]

• I've read Brief overview section and do understand basic concepts. [Yes]
• I've read F.A.Q. section and haven't found an answer to my question. [Yes]
• I've read Code of Conduct, I promise to be polite and will do my best at being constructive. [Yes]

---

Hi. I'm trying to add Hunter (v0.23.288) into an existing project which already has some external dependencies managed in various ways: some are expected to be installed system-wide (e.g. Boost), some are copied into the project itself as git submodules. After modifying the top-level CMake file it has roughly the following sequence of instructions:

cmake_minimum_required(VERSION 3.11)

# Including HunterGate breaks the CMake configuration step.
# Commenting the next 4 lines allows the project to be configured and built.
include("cmake/HunterGate.cmake")
HunterGate(
    URL "https://github.com/cpp-pm/hunter/archive/v0.23.288.tar.gz"
    SHA1 "6c9b2bc606d86ae31f96a62fc68f0a593024815b"
)

project(foo LANGUAGES CXX)

find_package(Boost COMPONENTS filesystem REQUIRED)

# It does not matter if we actually bring any dependency in using Hunter.
# Leaving this commented simply as a demo where such code would be in a real project.
#hunter_add_package(log4cplus)
#find_package(log4cplus CONFIG REQUIRED)

# mylib.cpp is just `int main() {}`. This library builds OK unless HunterGate is introduced.
# `add_library` (not `find_package` above) is what CMake will complain about when Hunter is enabled.
add_library(MyLibrary SHARED mylib.cpp)
target_link_libraries(MyLibrary PUBLIC Boost::filesystem)

Unfortunately, this yields the following CMake configuration error pointing to the line with add_library(MyLibrary...):

Target "MyLibrary" links to target "Boost::filesystem" but the target was not
  found.  Perhaps a find_package() call is missing for an IMPORTED target, or
  an ALIAS target is missing?

Obviously, the project configures/builds fine unless I add hunter to the play (use HunterGate), and Boost is clearly being located correctly (even with Hunter enabled) as I see it from the CMake output:

-- Boost version: 1.69.0
-- Found the following Boost libraries:
--   filesystem

I'm aware that Hunter may be used to manage Boost and other libraries, but leaving this option aside for a moment: is the behaviour I observe expected/known?

Is there a way to work this around and let CMake use system-wide installed Boost? I believe, there should be such an option even when Hunter is capable to provide the dependency, esp. for cases of gradual transition to Hunter or because of other reasons.

Info on my env if this helps: Mac OS 10.15, CMake version 3.18.4, Boost installed under /usr/local.

Many thanks!

[NeroBurner]

Your Problem is probably that your system FindBoost.cmake is not providing your required Boost::filesystem target. You can check that with the following cmake code

if(NOT TARGET Boost::filesystem)
  message(FATAL_ERROR "Missing required target")
endif()

[xzxzzxzxzca]

Your Problem is probably that your system FindBoost.cmake is not providing your required Boost::filesystem target.

Then how can it work without Hunter?
It does work without Hunter - just in case it wasn't clear from my initial description.

[NeroBurner]

As first step make sure a minimal CMakeLists.txt with just searching Boost::filesystem and then linking it to a foo executable works with your system boost (no Hunter at all)

After that, add Hunter to the mix and disable/enable it to see if the fault lies with Hunter. After that wee need to investigate further

[xzxzzxzxzca]

As first step make sure a minimal CMakeLists.txt with just searching Boost::filesystem and then linking it to a foo executable works with your system boost (no Hunter at all)

After that, add Hunter to the mix and disable/enable it to see if the fault lies with Hunter. After that wee need to investigate further

That is exactly what I did and described in my opening post. Could you please read it? It also contains the minimal CMakeLists.txt which can be turned into a fully buildable project with a few edits (I will even update it now to make testing as trivial as it can possibly be).

[NeroBurner]

I'm just making sure, methodically debugging your problem. Can't debug on your computer 🤷‍♂️

So please be very concise what you tested, how you tested it, and what the outputs were

have you tried the following?

cmake_minimum_required(VERSION 3.11)
project(foo LANGUAGES CXX)

find_package(Boost COMPONENTS filesystem REQUIRED)

# mylib.cpp is just `int main() {}`. This library builds OK unless HunterGate is introduced.
# `add_library` (not `find_package` above) is what CMake will complain about when Hunter is enabled.
add_library(MyLibrary SHARED mylib.cpp)
target_link_libraries(MyLibrary PUBLIC Boost::filesystem)

[NeroBurner]

Otherwise maybe this will help you find your answer
https://hunter.readthedocs.io/en/latest/faq/interaction-with-other-package-managers.html

[xzxzzxzxzca]

So please be very concise what you tested, how you tested it, and what the outputs were

Did I not describe the exact scenario, the exact environment, and the exact output in my opening post?

have you tried the following?

Yes, that's the example I posted to reproduce the problem. I would not post this here if I did not try it myself.

Otherwise maybe this will help you find your answer
https://hunter.readthedocs.io/en/latest/faq/interaction-with-other-package-managers.html

No it will not help the issue. I have read this prior to opening the bug report.

Honestly, I don't see what additional input I can provide here. It seems I'm answering the same questions over and over again.

[NeroBurner]

It works on Ubuntu 20.04 (docker image ubuntu:focal, run with podman with the command podman run -it --rm -v${PWD}:${PWD} ubuntu:focal /bin/bash).

Can't test on mac unfortunately

foo.cpp contents

#include <iostream>
int main()
{
	std::cout << "hello" << std::endl;
	return 0;
}

CMakeLists.txt without Hunter

cmake_minimum_required(VERSION 3.11)
project(foo LANGUAGES CXX)
find_package(Boost COMPONENTS filesystem REQUIRED)
add_executable(foo foo.cpp)
target_link_libraries(foo PUBLIC Boost::filesystem)

configure and build project without hunter using system library installed with sudo apt install libboost-filesystem-dev

root@4af0aa80e862:/home/nero/repos/boost_issue# cmake -S . -B _build                     
-- The CXX compiler identification is GNU 9.3.0
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found Boost: /usr/lib/x86_64-linux-gnu/cmake/Boost-1.71.0/BoostConfig.cmake (found version "1.71.0") found components: filesystem 
-- Configuring done
-- Generating done
-- Build files have been written to: /home/nero/repos/boost_issue/_build
root@4af0aa80e862:/home/nero/repos/boost_issue# cmake --build _build/
Scanning dependencies of target foo
[ 50%] Building CXX object CMakeFiles/foo.dir/foo.cpp.o
[100%] Linking CXX executable foo
[100%] Built target foo

Modify CMakeLists.txt and get the cmake/HunterGate.cmake file

cmake_minimum_required(VERSION 3.11)
include("cmake/HunterGate.cmake")
HunterGate(
    URL "https://github.com/cpp-pm/hunter/archive/v0.23.288.tar.gz"
    SHA1 "6c9b2bc606d86ae31f96a62fc68f0a593024815b"
)
project(foo LANGUAGES CXX)
find_package(Boost COMPONENTS filesystem REQUIRED)
add_executable(foo foo.cpp)
target_link_libraries(foo PUBLIC Boost::filesystem)

commands run to configure and build (hunter disabled with HUNTER_ENABLED=OFF)

root@4af0aa80e862:/home/nero/repos/boost_issue# cmake -S . -B _build -DHUNTER_ENABLED=OFF
-- The CXX compiler identification is GNU 9.3.0
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found Boost: /usr/lib/x86_64-linux-gnu/cmake/Boost-1.71.0/BoostConfig.cmake (found version "1.71.0") found components: filesystem 
-- Configuring done
-- Generating done
-- Build files have been written to: /home/nero/repos/boost_issue/_build
root@4af0aa80e862:/home/nero/repos/boost_issue# cmake --build _build/
Scanning dependencies of target foo
[ 50%] Building CXX object CMakeFiles/foo.dir/foo.cpp.o
[100%] Linking CXX executable foo
[100%] Built target foo

lastly build with Hunter providing Boost::filesystem

cmake -S . -B _build -DHUNTER_ENABLED=ON
-- [hunter] Initializing Hunter workspace (6c9b2bc606d86ae31f96a62fc68f0a593024815b)
-- [hunter]   https://github.com/cpp-pm/hunter/archive/v0.23.288.tar.gz
-- [hunter]   -> /root/.hunter/_Base/Download/Hunter/0.23.288/6c9b2bc
-- The CXX compiler identification is GNU 9.3.0
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
Boost  found.
Found Boost components:
   filesystem
-- Configuring done
-- Generating done
-- Build files have been written to: /home/nero/repos/boost_issue/_build
root@4af0aa80e862:/home/nero/repos/boost_issue# cmake --build _build/
Scanning dependencies of target foo
[ 50%] Building CXX object CMakeFiles/foo.dir/foo.cpp.o
[100%] Linking CXX executable foo
[100%] Built target foo

[xzxzzxzxzca]

You did not try the scenario I described, which is: Hunter is added to the project and is enabled but it is NOT managing the Boost dependency. Boost should be installed system-wide, NOT via Hunter.

But I tried this in Ubuntu 20.04 myself, as you did, and I do not reproduce it there. Might be a MacOS specific bug then.