Cannot link kfr_dft

[ImperiumAeternum]

KFR_DFT compiles inside kfr directory, but doesn't link

My CMakeLists.txt:

add_subdirectory(kfr)
set(CMAKE_CXX_COMPILER clang++)
set(CMAKE_C_COMPILER clang)
target_link_libraries(FindAndSmooth kfr kfr_io kfr_dft)

Inside kfr subdirectory kfr compiles fine:

root@vlad-:/home/vlad/myapp/kfr# make -j4
-- CPU_ARCH=avx2
-- Configuring done
-- Generating done
-- Build files have been written to: /home/vlad/myapp
[ 25%] Building CXX object kfr/CMakeFiles/detect_cpu.dir/cmake/detect_cpu.cpp.o
[ 50%] Building CXX object kfr/CMakeFiles/kfr_io.dir/include/kfr/io/impl/audiofile-impl.cpp.o
[ 75%] Linking CXX executable detect_cpu
[ 75%] Built target detect_cpu
[100%] Linking CXX static library libkfr_io.a
[100%] Built target kfr_io

I've made sure it compiles with Clang, but it doesn't help

root@vlad:/home/vlad/myapp# find /usr/bin/clang++ && find /usr/bin/clang
/usr/bin/clang++
/usr/bin/clang
root@vlad:/home/vlad/myapp# export CXX=/usr/bin/clang++
root@vlad:/home/vlad/myapp# export CC=/usr/bin/clang
root@vlad:/home/vlad/myapp# make
Consolidate compiler generated dependencies of target kfr_io
[  4%] Built target kfr_io
Consolidate compiler generated dependencies of target MyApp
[  6%] Linking CXX executable MyApp
/usr/bin/ld: cannot find -lkfr_dft: No such file or directory