Why does the application compile but fails at linking stage, after adding new functions to a class?

Question

My project is being built using the following: Eclipse, CMakeLists.txt, MinGW 4.8.1

The project compiles and application links normally. But after adding,

3 Functions in 'Helper.cpp' and 2 Functions in 'CamData.cpp' , of the type boost::ublas::matrix

The linker gives up, and can not find the functions anymore (undefined reference Error) though it can compile them (no error while compiling the object files *.cpp.obj).

Code Structure

Main.cpp
CMain.cpp
Helper.cpp (Boost::ublas::matrix<double> Fnction1, ...) 
CamData.cpp (Boost::ublas::matrix<double> Funtion4, ...)

The functions in Helper class that were created are as follows. The 2 functions in CamData are also of similar type:

class Helper{
    Helper();
    virtual ~Helper();
template<typename T>
using bMatrix =  boost::numeric::ublas::matrix<T>;

bMatrix<double> getmatrixQ(double w, double x, double y, double z);
bMatrix<double> rotate_x(bMatrix<double> M, double angleinrad);  
bMatrix<double> getTransformationMatrix(bMatrix<double> M, double x, double y, double z);
};

The relevant parts of the cmakelist.txt are as follows:

FIND_PACKAGE (Boost REQUIRED COMPONENTS date_time filesystem system)
INCLUDE_DIRECTORIES(${Boost_INCLUDE_DIRS})
LINK_DIRECTORIES(${Boost_LIBRARY_DIRS})

INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR}/../src)
INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR}/../src/InputParams)
INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR}/../src/Utilities)

SET(CMAKE_CXX_FLAGS "${warnings}" 
    CACHE STRING "Flags used by the compiler during all build types" FORCE)
SET(CMAKE_CXX_FLAGS "-Wall -std=c++11")

ADD_EXECUTABLE(${PROJECT_NAME} ${CMAKE_CURRENT_SOURCE_DIR}/../src/main.cpp
                               ${CMAKE_CURRENT_SOURCE_DIR}/../src/Utilities/CHelper.cpp
                               ${CMAKE_CURRENT_SOURCE_DIR}/../src/InputParams/CCamData.cpp
                               ${CMAKE_CURRENT_SOURCE_DIR}/../src/CMain.cpp
                               ${CMAKE_CURRENT_SOURCE_DIR}/../src/COutput.cpp
                               ${CMAKE_CURRENT_SOURCE_DIR}/../src/CThreads.cpp)

TARGET_LINK_LIBRARIES (${PROJECT_NAME}  ${Boost_LIBRARIES})

After commenting out the functions and thier calls in main.cpp the program can be linked again. Any Ideas on what could be causing this?

Error Log Below

[100%] Linking CXX executable Project.exe
CMakeFiles\Project.dir/objects.a(main.cpp.obj):main.cpp:(.text+0x116c): undefined reference to `esg::CHelper::getmatrixQ(double, doubl
e, double, double)'
CMakeFiles\Project.dir/objects.a(main.cpp.obj):main.cpp:(.text+0x1230): undefined reference to `esg::CHelper::rotate_x(boost::numeric:
:ublas::matrix<double, boost::numeric::ublas::basic_row_major<unsigned int, int>, boost::numeric::ublas::unbounded_array<double, std::alloca
tor<double> > >, double)'
CMakeFiles\Project.dir/objects.a(main.cpp.obj):main.cpp:(.text+0x1344): undefined reference to `esg::CHelper::getTransformationMatrix(
boost::numeric::ublas::matrix<double, boost::numeric::ublas::basic_row_major<unsigned int, int>, boost::numeric::ublas::unbounded_array<doub
le, std::allocator<double> > >, double, double, double)'
CMakeFiles\Project.dir/objects.a(main.cpp.obj):main.cpp:(.text+0x149d): undefined reference to `esg::CCamData::initpinhole(esg::Pinhol
eIntrinsics&)'
CMakeFiles\Project.dir/objects.a(main.cpp.obj):main.cpp:(.text+0x15d3): undefined reference to `esg::CCamData::createProjectionMatrix(
boost::numeric::ublas::matrix<double, boost::numeric::ublas::basic_row_major<unsigned int, int>, boost::numeric::ublas::unbounded_array<doub
le, std::allocator<double> > >, boost::numeric::ublas::matrix<double, boost::numeric::ublas::basic_row_major<unsigned int, int>, boost::nume
ric::ublas::unbounded_array<double, std::allocator<double> > >&, long)'
collect2.exe: error: ld returned 1 exit status
CMakeFiles\Project.dir\build.make:548: recipe for target 'Project.exe' failed
mingw32-make.exe[2]: *** [Project.exe] Error 1
CMakeFiles\Makefile2:66: recipe for target 'CMakeFiles/Project.dir/all' failed
mingw32-make.exe[1]: *** [CMakeFiles/Project.dir/all] Error 2
Makefile:82: recipe for target 'all' failed
mingw32-make.exe: *** [all] Error 2

We need a minimal, complete example. Please remove the tags c++11 and boost, as they are duplicate or unrelated. — usr1234567, Sep 09 '16 at 15:08
Now 'Minimal and Complete' it is! :-) Any insights towards the solution, apart from the vote down? — Tomar, Sep 09 '16 at 15:55
According to the error log, no source file you use for `add_executable` *implements* given functions. Note, that implementation should use exactly same signature and namespace as declaration. — Tsyvarev, Sep 09 '16 at 19:17

score 0 · Accepted Answer · answered Sep 12 '16 at 19:39

Well, here's why I recieved the error while linking and not while compiling.

The functions in the cpp files were declared like this:

Type Function_Name (arguments)
{
  // do something
}

but it should have been like this:

Type Class_name::Function_Name (arguments)
{
  // do something
}

Hence it could not find them while linking but could compile them individually in the cpp file.

Why does the application compile but fails at linking stage, after adding new functions to a class?

1 Answers1