CMake Ubuntu set soname for shared object - linux

Question

How to set the SONAME for a shared library with CMake in Ubuntu?
With help of How to add linker flag for libraries with CMake? I have created a CMakeLists.txt:
project(mylib VERSION 1.2.3)
set(src_files_mylib
Client.cpp
Server.cpp
)
set(hdr_files_mylib
Client.h
Server.h
)
add_library(mylib SHARED ${src_files_mylib} ${hdr_files_mylib})
set_target_properties(mylib PROPERTIES PREFIX "")
set_target_properties(mylib PROPERTIES SUFFIX "")
set_target_properties(mylib PROPERTIES OUTPUT_NAME "mylib.so.${PROJECT_VERSION}")
add_link_options("LINKER: -l,soname,mylib.so.${PROJECT_VERSION_MAJOR}")
Using CMake 3.16 and out of source build. It produces the library named mylib.so.1.2.3 but it does not seem to have an SONAME in it. When executing ldconfig -n . in the library dir, it does not produce a link.
set(CMAKE_SHARED_LINKER_FLAGS "-Wl,soname,mylib.so.${PROJECT_VERSION_MAJOR}")
instead of
add_link_options("LINKER: -l,soname,mylib.so.${PROJECT_VERSION_MAJOR}")
behaves the same to me.
When writing the Makefile manually, the target is built correctly with this (going ldconfig -n . like above produces a link):
(...)
MYLIB_SO=mylib.so.$(VERSION_MAJOR).$(VERSION_MINOR).$(VERSION_PATCH)
MYLIB_SONAME=mylib.so.$(VERSION_MAJOR)
(...)
$(MYLIB_SO): $(OBJ_MYLIB)
$(CXX) $(SO_FLAGS) -Wl,-soname,$(MYLIB_SONAME) -o $(MYLIB_SO) $(DEBUGFLAGS) $(OBJ_MYLIB)

Answer 1

if libraries is called SoundTouch
project(SoundTouch VERSION 2.3.0 LANGUAGES CXX)
add_library(SoundTouch [SHARED]
sources/animation.cpp
sources/buffers.cpp
[...]
)
set_target_properties(SoundTouch PROPERTIES VERSION ${CMAKE_PROJECT_VERSION}
SOVERSION ${PROJECT_VERSION_MAJOR} )