Cannot get Cmake to bake rpath into executable if prefix used - cmake

Question

I have a cmake setup that makes an executable and a shared library I'm using a non-standard install prefix and want to bake the RPATH into the executable. Reading a bunch of previous questions as well as the kitware wiki leads me to this:
Top CMakeLists.txt:
cmake_minimum_required( VERSION 3.14 )
project( cmakeprogram VERSION 1.0 )
add_executable( program program.cxx )
set( CMAKE_RPATH "${CMAKE_INSTALL_PREFIX}/lib" )
set( CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib" )
set( CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE )
add_subdirectory( lib )
target_include_directories( auxlib PUBLIC "${CMAKE_CURRECT_SOURCE_DIR}" )
target_link_libraries( program PUBLIC auxlib )
install( TARGETS program DESTINATION . )
Library:
cmake_minimum_required( VERSION 3.14 )
project( auxlib )
set( CMAKE_RPATH "${CMAKE_INSTALL_PREFIX}/lib" )
set( CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib" )
set( CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE )
add_library( auxlib SHARED
aux.cxx aux.h )
target_include_directories( auxlib PUBLIC "${CMAKE_CURRECT_SOURCE_DIR}" )
install( TARGETS auxlib DESTINATION lib )
Running ldd on the program (SuSe linux if it matters) in the build & isntall location respectively gives:
build
libauxlib.so => /stuff/build-publiclib/lib/libauxlib.so (0x00002ad64984c000)
prefix
libauxlib.so => not found
Yes, I have read https://gitlab.kitware.com/cmake/community/-/wikis/doc/cmake/RPATH-handling but 1. that seems to be about cmake 2.whatever and 2. still doesn't get me the correct solution.

Answer 1

It is not so obvious from the article, but variables CMAKE_INSTALL_RPATH and CMAKE_INSTALL_RPATH_USE_LINK_PATH should be set before creation of the target:
cmake_minimum_required( VERSION 3.14 )
project( cmakeprogram VERSION 1.0 )
# All further targets on installation will have given RPATH.
set( CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib" )
add_executable( program program.cxx )
add_subdirectory( lib )
Funny thing that even documentation of CMAKE_INSTALL_RPATH variable is misleading:
This is used to initialize the target property INSTALL_RPATH for all targets.
But description of the INSTALL_RPATH correctly specifies the situation:
This property is initialized by the value of the variable CMAKE_INSTALL_RPATH if it is set when a target is created.
Actually, in CMake initialization of the most target properties from variables follows the clause bolded above.