CMake Linking library with full path and with target_include

I came to a problem that I do not understand why this works in such a ways. I am linking static libraries, specially libgmp-10 and libmpfr-4. These are static libraries from CGAL.

This does not work:

list(APPEND petras_include_paths 
  #cgal
  "${CMAKE_BINARY_DIR}/install/cgal/include"
  "${CMAKE_BINARY_DIR}/install/cgal/auxiliary/gmp/include"
  "${CMAKE_BINARY_DIR}/install/cgal/auxiliary/gmp/lib"
  #"C:/msys64/mingw64/lib/" #GCC
  )

 target_include_directories(${PROJECT_NAME} PRIVATE "$<BUILD_INTERFACE:${petras_include_paths}>") #header for the library

target_link_libraries(${PROJECT_NAME} PRIVATE 
  libgmp-10
  libmpfr-4
  )

This works:

target_link_libraries(${PROJECT_NAME} PRIVATE 
  "${CMAKE_BINARY_DIR}/install/cgal/auxiliary/gmp/lib/libgmp-10.lib" 
  "${CMAKE_BINARY_DIR}/install/cgal/auxiliary/gmp/lib/libmpfr-4.lib"
  )

Why? I thought that target_include_directories add the path to libraries, so that in target_link_libraries I should only need to specify the name of the library, not the full path.

CodePudding user response：

Absolute paths should NEVER appear in CMakeLists.txt.

Proper way to do it is:

find_package(CGAL)

...
target_link_libraries(${PROJECT_NAME} CGAL::CGAL)

As it is documented.

cgal should be just properly installed on a system.

CodePudding user response：

target_include_directories adds #include directories, not library search paths. target_link_directories adds link directories.

Before proceeding, you might want to read https://doc.cgal.org/latest/Manual/devman_create_and_use_a_cmakelist.html