undefined reference with shared library using cmake

Question

I have looked a lot of placed to find this answer, but I have not been able to find anything that pertains to my situation. It seems so easy, which is why this is so frustrating.

I am building a project with CMAKE. I am generating two shared libraries. One includes the other. I am also generating an executable. The executable is linking to the shared library that encapsulates the other one. Here is the relevant portion of the code:

################################################################################ 
# Make the shared libraries                                                             
################################################################################ 
# Standard stuff                                                                 
add_library(er SHARED src/std_math.cc src/snapshot.cc)                           
include_directories(hdr)                                                         
target_link_libraries(er rt)                                                     
# DSP library                                                                    
add_library(dsp SHARED src/dsp.cc)                                               
include_directories(hdr)                                                         
target_link_libraries(dsp er /usr/lib/libfftw3f.so /usr/lib/libfftw3.so)         
################################################################################ 
# Make an Executable                                                             
################################################################################ 
message("-- Making executable for testing --")                                   
add_executable(er_test test/dsp_test.cc)                                         
include_directories(hdr)                                                         
target_link_libraries(er_test dsp)                                               
################################################################################ 
# What to do with make install                                                   
################################################################################ 
message ("-- Writting install scripts --")                                       
# See if there is an install directory already assigned.  If not, set it to the  
# system default.                                                                
if (NOT DEFINED INSTALL_DIR)                                                     
    set (INSTALL_DIR /usr/local/)                                                
endif (NOT DEFINED INSTALL_DIR)                                                  
message ("  -- install_dir = ${INSTALL_DIR}")                                    
# Install the libraries and header files to the appropriate places               
install (TARGETS er dsp DESTINATION ${INSTALL_DIR}/bin)                          
install (FILES hdr/dsp.hh hdr/snapshot.hh hdr/std_math.hh DESTINATION ${INSTALL_DIR}/include)

Here is the error I get.

CMakeFiles/er_test.dir/test/dsp_test.cc.o: In function `main':
dsp_test.cc:(.text.startup+0x11e): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& operator<< <int>(std::basic_ostream<char, std::char_traits<char> >&, std::vector<int, std::allocator<int> > const&)'
dsp_test.cc:(.text.startup+0x142): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& operator<< <int>(std::basic_ostream<char, std::char_traits<char> >&, std::vector<int, std::allocator<int> > const&)'
dsp_test.cc:(.text.startup+0x166): undefined reference to `std::vector<int, std::allocator<int> > subvec<int>(std::vector<int, std::allocator<int> > const&, int, int, int)'
dsp_test.cc:(.text.startup+0x182): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& operator<< <int>(std::basic_ostream<char, std::char_traits<char> >&, std::vector<int, std::allocator<int> > const&)'
dsp_test.cc:(.text.startup+0x1b6): undefined reference to `std::vector<int, std::allocator<int> > subvec<int>(std::vector<int, std::allocator<int> > const&, int, int, int)'

and there are many more where those came from. I have tried using static libraries, but then it just delays the problem until the next executable I try to include these libraries into. I have also tried using g++ instead of c++. I've tried swapping around library orders. Also, it is not a template issue since at least one of the references it can't find is not a templated function. I have searched the libraries for the symbols, and I was able to find them, although they were prepended and postpended by random characters.

I don't understand what's going on. Please help.

Thanks,

UPDATE

I found another link, specifically this one, that mentioned potential problems with add_subdirectory. This is a subproject to another project. So I sent into the project and built there. It worked! It still doesn't work in the parent directory though. Maybe that can give clues to someone.

Thanks again,

Solution

Don't assume that the directory containing CMakeLists.txt is the current directory at runtime. Instead, use ${CMAKE_CURRENT_SOURCE_DIR} whenever you want a path relative to the CMakeLists.txt. For example:

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/hdr)

Comments

[jrk0414]

Amazingly, that fixed it. I would never have thought that would be the problem. Thanks for the help.

[ostrokach]

I was banging my head over an apbs: symbol lookup error: [...] undefined symbol: X error. Turns out it was caused by an include_directories('/src') in the CMake file. CMake was pointing me in the right direction with the warning: "This command specifies the relative path as a link directory. Policy CMP0015 is not set: link_directories() treats paths relative to the source dir. Run "cmake --help-policy CMP0015" for policy details. Use the cmake_policy command to set the policy and suppress this warning." Guess I should have listened!