How do I link tf_conversions to a RViz panel?

edit

I am designing a Qt panel that is integrated into RViz. At some point this Qt panel needs to convert an Eigen::Affine3d to a geometry_msg::Pose.

I fail to understand why tf_conversions is not linked to my package:

CMakeLists.txt

cmake_minimum_required(VERSION 2.8.3)
project(custom_rviz_plugin)

find_package(catkin REQUIRED COMPONENTS
             geometry_msgs
             rviz
             tf
             tf_conversions)

catkin_package()

include_directories(${catkin_INCLUDE_DIRS})

find_package(Qt4 COMPONENTS QtCore QtGui REQUIRED)
include(${QT_USE_FILE})

add_definitions(-DQT_NO_KEYWORDS)

qt4_wrap_cpp(MOC_FILES
  src/my_panel.h
)

set(SOURCE_FILES
  src/my_panel.cpp 
  ${MOC_FILES}
)

add_library(${PROJECT_NAME} ${SOURCE_FILES})
target_link_libraries(${PROJECT_NAME} ${QT_LIBRARIES} ${catkin_LIBRARIES})

install(TARGETS
  ${PROJECT_NAME}
  ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
  LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
  RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
)

install(FILES 
  plugin_description.xml
  DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION})

package.xml

<?xml version="1.0"?>
<package format="2">
  <name>custom_rviz_plugin</name>
  <version>0.1.0</version>
  <description>RViz plugin.</description>
  <author>Victor Lamoine - Institut Maupertuis</author>
  <maintainer email="victor.lamoine@gmail.com">Victor Lamoine</maintainer>
  <license>BSD</license>

  <buildtool_depend>catkin</buildtool_depend>

  <build_depend>rviz</build_depend>
  <build_depend>geometry_msgs</build_depend>
  <build_depend>tf</build_depend>
  <build_depend>tf_conversions</build_depend>

  <exec_depend>rviz</exec_depend>
  <exec_depend>geometry_msgs</exec_depend>
  <exec_depend>tf</exec_depend>
  <exec_depend>tf_conversions</exec_depend>

  <export>
      <rviz plugin="${prefix}/plugin_description.xml"/>
  </export>
</package>

The whole package is available here.

When adding the panel in RViz (using test.launch in the package) the constructor crashes because of a missing symbol:

/opt/ros/indigo/lib/rviz/rviz: symbol lookup error: /home/victor/MEGAsync/catkin_workspace/devel/lib//libcustom_rviz_plugin.so: undefined symbol: _ZN2tf14poseEigenToMsgERKN5Eigen9TransformIdLi3ELi2ELi0EEERN13geometry_msgs5Pose_ISaIvEEE

Which is confirmed because tf_conversions is not linked to the Qt panel library:

$ ldd /home/victor/MEGAsync/catkin_workspace/devel/lib//libcustom_rviz_plugin.so | grep tf
    libtf.so => /opt/ros/indigo/lib/libtf.so (0x00007fd1b1af1000)
    libtf2_ros.so => /opt/ros/indigo/lib/libtf2_ros.so (0x00007fd1adfe2000)
    libtf2.so => /opt/ros/indigo/lib/libtf2.so (0x00007fd1addb2000)

How do I link tf_conversions to a Qt / RViz panel?

EDIT 1: Even linking manually does not work:

set (CMAKE_CXX_FLAGS "-fPIC -L/opt/ros/indigo/lib/ -ltf_conversions")

The library is still not linked to tf_conversions.

EDIT 2: My work-around at the moment is to re-declare the function:

namespace tf {

template<typename T>
void poseEigenToMsgImpl(const T &e, geometry_msgs::Pose &m)
{
  m.position.x = e.translation()[0];
  m.position.y = e.translation()[1];
  m.position.z = e.translation()[2];
  Eigen::Quaterniond q = (Eigen::Quaterniond)e.linear();
  m.orientation.x = q.x();
  m.orientation.y = q.y();
  m.orientation.z = q.z();
  m.orientation.w = q.w();
  if (m.orientation.w < 0) {
    m.orientation.x *= -1;
    m.orientation.y *= -1;
    m.orientation.z *= -1;
    m.orientation.w *= -1;
  }
}

void poseEigenToMsg(const Eigen::Affine3d &e, geometry_msgs::Pose &m)
{
  poseEigenToMsgImpl(e, m);
}

void poseEigenToMsg(const Eigen::Isometry3d &e, geometry_msgs::Pose &m)
{
  poseEigenToMsgImpl(e, m);
}

} // tf