Add boost program_options as a git submodule and build an executable with its sources

Question

I have a small project that uses boost::program_options. I want to add this (only this) library to my project as a git submodule and build my executable using its sources.

I have already done the git submodule part (git submodule add https://github.com/boostorg/program_options.git), and I have done a small experiment in which I build an example application using only the sources in the mentioned submodule (to double check that there are not extra dependencies).

Now I want to add these sources to my project. What I do in my CMakeLists.txt file is:

set(BOOST_PROGRAM_OPTIONS_SOURCES
  boost/program_options/src/split.cpp
  boost/program_options/src/positional_options.cpp
  boost/program_options/src/parsers.cpp
  boost/program_options/src/options_description.cpp
  boost/program_options/src/convert.cpp
  boost/program_options/src/config_file.cpp
  boost/program_options/src/cmdline.cpp
  boost/program_options/src/winmain.cpp
  boost/program_options/src/variables_map.cpp
  boost/program_options/src/value_semantic.cpp
  boost/program_options/src/utf8_codecvt_facet.cpp
)

and

add_executable(
  ...
  src/main.cpp
  ${BOOST_PROGRAM_OPTIONS_SOURCES}
)

but I obtain the following error:

CMake Error at CMakeLists.txt:69 (add_executable):
  The target name "boost/program_options/src/split.cpp" is reserved or not
  valid for certain CMake features, such as generator expressions, and may
  result in undefined behavior.


CMake Error at CMakeLists.txt:86 (target_link_libraries):
  Cannot specify link libraries for target "..." which is not built
  by this project.

What is the right way to do what I want>

Answer 1

I have found the problem.

I have cloned boost::program_options (git clone https://github.com/boostorg/program_options.git) in the same folder as the CMakeLists.txt

After that, following the normal FindBoost flow

set(Boost_USE_STATIC_LIBS OFF)
set(Boost_USE_MULTITHREADED OFF)
set(Boost_USE_STATIC_RUNTIME OFF)

find_package(Boost 1.45.0 COMPONENTS program_options)

if(Boost_FOUND)
  message(WARNING "BOOST FOUND")
  include_directories(${Boost_INCLUDE_DIRS})
  set(BOOST_LIBS ${Boost_LIBRARIES})
else()
  set(BOOST_LIBS )
  message(WARNING "BOOST NOT FOUND")
endif()
...
...
target_link_libraries(... ${BOOST_LIBS})
...
...

CMake is able to find boost even though program_options does not contain any CMakeLists.txt (I can't find it at least)