CMake FIND_PACKAGE succeeds but returns wrong path

Question

I'm trying to have CMake 2.8.6 link to boost::program_options using the following code in my CMakeLists.txt

FIND_PACKAGE(Boost COMPONENTS program_options REQUIRED)
INCLUDE_DIRECTORIES (${Boost_INCLUDE_DIR})

ADD_EXECUTABLE (segment segment.cpp)
TARGET_LINK_LIBRARIES (segment ${Boost_LIBRARIES})

The find command seems to succeed but passes the wrong directory to the linker. The package is actually in:

`/usr/lib64/libboost_program_options-mt.so.5`

but CMakeFiles/segment.dir/link.txt lists the following:

/cm/shared/apps/gcc/4.4.6/bin/c++       CMakeFiles/segment.dir/segment.cpp.o  -o segment -rdynamic /usr/lib64/lib64/libboost_program_options-mt.so.5 -lpthread -lrt -Wl,-rpath,/usr/lib64/lib64

Note the extra lib64 in the path. Also, the -l flag in front of the path seems to be missing.

When running CMake it reports that it correctly finds the package, and the {$Boost_LIBRARIES} variable seems to list the correct libs:

Boost  found.
Found Boost components:
   program_options
${Boost_LIBRARIES} - optimized;boost_program_options-mt-shared;debug;boost_program_options-mt-shared-debug

The generated CMakeCache.txt file starts with:

//The directory containing a CMake configuration file for Boost.
Boost_DIR:PATH=/usr/lib64/boost

//Boost include directory
Boost_INCLUDE_DIR:FILEPATH=/usr/include

Which seems to be correct. But when running make it uses the path in link.txt above and I get the error:

make[2]: *** No rule to make target `/usr/lib64/lib64/libboost_program_options-mt.so.5', needed by `segment'.  Stop.
make[1]: *** [CMakeFiles/segment.dir/all] Error 2
make: *** [all] Error 2

What might cause this extra injection of a subdir into the path? What might cause link.txt to be generated in this way? And how do I fix it (or work around it)?

Answer 1

This problem occurs when using some older versions of boost with cmake-2.8.6-rc2 or later, where the boost package finding code was changed.

The problem can be worked around by specifying -DBoost_NO_BOOST_CMAKE=ON on the cmake command line.

The actual commit where this problem is introduced is 7da796d1fdd7cca07df733d010cd343f6f8787a9, and can be viewed here.

Answer 2

The problem is with the boost-devel distributed file: /usr/lib64/boost/Boost-relwithdebinfo.cmake

The cmake-2.6 package does not use this file at all, because the FindBoost.cmake file returns (correct) full-paths to boost libraries. The cmake28-2.8.8 FindBoost.cmake file returns library strings like "boost_date_time-mt-shared", which are targets defined in /usr/lib64/boost/Boost-relwithdebinfo.cmake.

At the very top of /usr/lib64/boost/Boost-relwithdebinfo.cmake, a variable named _IMPORT_PREFIX is defined from the location of the cmake file itself, and then used like so:

#----------------------------------------------------------------
# Generated CMake target import file for configuration "RelWithDebInfo".
#----------------------------------------------------------------

# Commands may need to know the format version.
SET(CMAKE_IMPORT_FILE_VERSION 1)

# Compute the installation prefix relative to this file.
GET_FILENAME_COMPONENT(_IMPORT_PREFIX "${CMAKE_CURRENT_LIST_FILE}" PATH)
GET_FILENAME_COMPONENT(_IMPORT_PREFIX "${_IMPORT_PREFIX}" PATH)

# Import target "boost_date_time-static" for configuration "RelWithDebInfo"
SET_PROPERTY(TARGET boost_date_time-static APPEND PROPERTY IMPORTED_CONFIGURATIONS RELWITHDEBINFO)
SET_TARGET_PROPERTIES(boost_date_time-static PROPERTIES
  IMPORTED_LOCATION_RELWITHDEBINFO "${_IMPORT_PREFIX}/lib64/libboost_date_time.a"
  )

This sets _IMPORT_PREFIX to "/usr/lib64", which is concatenated with another string that has /lib64/ in it as well. I found that if I simply change the file to include a 3rd GET_FILENAME_COMPONENT call, it works fine. Like so:

#----------------------------------------------------------------
# Generated CMake target import file for configuration "RelWithDebInfo".
#----------------------------------------------------------------

# Commands may need to know the format version.
SET(CMAKE_IMPORT_FILE_VERSION 1)

# Compute the installation prefix relative to this file.
GET_FILENAME_COMPONENT(_IMPORT_PREFIX "${CMAKE_CURRENT_LIST_FILE}" PATH)
GET_FILENAME_COMPONENT(_IMPORT_PREFIX "${_IMPORT_PREFIX}" PATH)
GET_FILENAME_COMPONENT(_IMPORT_PREFIX "${_IMPORT_PREFIX}" PATH)

# Import target "boost_date_time-static" for configuration "RelWithDebInfo"
SET_PROPERTY(TARGET boost_date_time-static APPEND PROPERTY IMPORTED_CONFIGURATIONS RELWITHDEBINFO)
SET_TARGET_PROPERTIES(boost_date_time-static PROPERTIES
  IMPORTED_LOCATION_RELWITHDEBINFO "${_IMPORT_PREFIX}/lib64/libboost_date_time.a"
  )