Linking boost_numpy3 with CMAKE - c++

Question

TL;DR When updating from CMake 3.10 to CMake 3.11.1 on archlinux, the following configuration line:
find_package(Boost COMPONENTS python3 COMPONENTS numpy3 REQUIRED)
leads to CMake linking against 3 different libraries
-- Boost version: 1.66.0
-- Found the following Boost libraries:
-- python3
-- numpy3
-- python
instead of the previous behaviour:
-- Boost version: 1.66.0
-- Found the following Boost libraries:
-- python3
-- numpy3
resulting in a linker error.
I use CMake to build a piece of software that relies on Boost python, and, since a couple of days ago, it seems that the line
find_package(Boost COMPONENTS numpy3 REQUIRED)
is no longer sufficient for CMake to understand that it should link the program against the Boost python3 library, and it uses the Boost library python instead.
Here is a minimal working example to reproduce what I am talking about.
test.cpp
#include <iostream>
using namespace std;
int main()
{
cout << "Hello, world!" << endl;
}
CMakeList.txt
set(CMAKE_VERBOSE_MAKEFILE ON)
find_package(PythonLibs 3 REQUIRED)
find_package(Boost COMPONENTS numpy3 REQUIRED)
add_executable (test test.cpp)
target_link_libraries(test ${Boost_LIBRARIES} ${PYTHON_LIBRARIES})
With this configuration of CMake, a linker error will occur, and the error persists when I change the line adding numpy to
find_package(Boost COMPONENTS python3 COMPONENTS numpy3 REQUIRED)
Here is the result of cmake . && make:
/home/rastapopoulos/test $ cmake .
-- Boost version: 1.66.0
-- Found the following Boost libraries:
-- numpy3
-- python
CMake Warning (dev) in CMakeLists.txt:
No cmake_minimum_required command is present. A line of code such as
cmake_minimum_required(VERSION 3.11)
should be added at the top of the file. The version specified may be lower
if you wish to support older CMake versions for this project. For more
information run "cmake --help-policy CMP0000".
This warning is for project developers. Use -Wno-dev to suppress it.
-- Configuring done
-- Generating done
-- Build files have been written to: /home/rastapopoulos/test
/home/rastapopoulos/test $ make
/usr/bin/cmake -H/home/rastapopoulos/test -B/home/rastapopoulos/test --check-build-system CMakeFiles/Makefile.cmake 0
/usr/bin/cmake -E cmake_progress_start /home/rastapopoulos/test/CMakeFiles /home/rastapopoulos/test/CMakeFiles/progress.marks
make -f CMakeFiles/Makefile2 all
make[1]: Entering directory '/home/rastapopoulos/test'
make -f CMakeFiles/test.dir/build.make CMakeFiles/test.dir/depend
make[2]: Entering directory '/home/rastapopoulos/test'
cd /home/rastapopoulos/test && /usr/bin/cmake -E cmake_depends "Unix Makefiles" /home/rastapopoulos/test /home/rastapopoulos/test /home/rastapopoulos/test /home/rastapopoulos/test /home/rastapopoulos/test/CMakeFi
les/test.dir/DependInfo.cmake --color=
make[2]: Leaving directory '/home/rastapopoulos/test'
make -f CMakeFiles/test.dir/build.make CMakeFiles/test.dir/build
make[2]: Entering directory '/home/rastapopoulos/test'
[ 50%] Linking CXX executable test
/usr/bin/cmake -E cmake_link_script CMakeFiles/test.dir/link.txt --verbose=1
/usr/bin/c++ -rdynamic CMakeFiles/test.dir/test.o -o test -lboost_numpy3 -lboost_python -lpython3.6m
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyString_Size'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyUnicodeUCS4_FromEncodedObject'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyFile_FromString'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyString_Type'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyInt_Type'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyString_FromString'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyUnicodeUCS4_AsWideChar'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyString_FromStringAndSize'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `Py_InitModule4_64'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyString_FromFormat'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyNumber_Divide'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyNumber_InPlaceDivide'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyInt_AsLong'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyString_InternFromString'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyClass_Type'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyString_AsString'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyInt_FromLong'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/../../../../lib/libboost_python.so: undefined reference to `PyFile_AsFile'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/test.dir/build.make:90: test] Error 1
make[2]: Leaving directory '/home/rastapopoulos/test'
make[1]: *** [CMakeFiles/Makefile2:71: CMakeFiles/test.dir/all] Error 2
make[1]: Leaving directory '/home/rastapopoulos/test'
make: *** [Makefile:87: all] Error 2
Has anyone experienced a similar problem and managed to solve it? I use cmake 3.11.1, boost 1.66.0-2, and run an updated version of Archlinux.

Answer 1

This bug is due to an invalid dependency description in FindBoost.cmake
set(_Boost_NUMPY_DEPENDENCIES python)
This has been fixed at https://github.com/Kitware/CMake/commit/c747d4ccb349f87963a8d1da69394bc4db6b74ed
Please use latest one, or you can rewrite it manually:
set(_Boost_NUMPY_DEPENDENCIES python${component_python_version})

Answer 2

CMake 3.10 does not properly support Boost 1.66. The Boost dependencies are hard-coded and if they chance, CMake has to adopt.
Delete the build directory and reconfigure. The configure step uses cached variables which prevents re-detection with the newer routines.