[CMake] CLANG vs GCC when linking executables

[Patrick Boettcher]

Hi list,

I'm trying to link an executable with a locally build and imported
dynamic library. The link-code generated by CMake differs when 
using GCC and Clang in regards to the rpath-options:

This is my cmake-code for importing the library (this code is actually
generated by using export() )

  add_library(systemc INTERFACE IMPORTED)
  set_target_properties(systemc PROPERTIES
    INTERFACE_COMPILE_DEFINITIONS "SC_INCLUDE_FX"
    INTERFACE_COMPILE_OPTIONS "-Wno-deprecated-declarations"
    INTERFACE_INCLUDE_DIRECTORIES "/local/path/include"
    INTERFACE_LINK_LIBRARIES "/local/path/lib/libsystemc.so")

  add_executable(testsc test.cpp)
  target_link_libraries(testsc systemc)

When now running cmake in a build-dir which uses by default gcc the
link-command contains:

  /usr/bin/g++ CMakeFiles/testsc.dir/test.cpp.o  -o testsc \
    -Wl,-rpath,/local/path/lib /local/path/lib/libsystemc.so

doing the same with clang++ as CXX-compiler (CXX=clang++ cmake
<src-path>) gives me a linker command not containing the -rpath-option:

  clang++ CMakeFiles/testsc.dir/test.cpp.o -o testsc \
    /local/path/lib/libsystemc.so

The link-process works, but when running the executable inside the
build-dir it is unable to find the library as neither the rpath is set
nor is this library-path known by the dynamic loader.

Is there anything I can do? Is this behavior expected? How should the
RPATH being handled when clang is used.

best regards,
--
Patrick.