Target requires the language dialect "CXX17" (with compiler extensions), but CMake does not know the

So I've been trying to include the <filesystem> into my project, which seem to be a bigger problem than I thought. <filesystem> should be part of c++17, I need to add that definition into my CMakeList.

My root CmakeLists look like this:

MESSAGE(“In src CMAKELIST”)

#
# Build everything in include/ directory
add_subdirectory(include)
#

#set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
#set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

## Main executable target
add_executable(cmakeDemo main.cpp)

# These libraries get built in include/*/, CMake will auto-set required
# compiler flags and include paths from their definitions
target_link_libraries(cmakeDemo record ${portaudio})
target_link_libraries(cmakeDemo database)
target_link_libraries(cmakeDemo match)
target_link_libraries(cmakeDemo spectogram)

In which I added the c++17 definition, but when I compile my system, I get this error:

 make 
“InsrcCMAKELIST”
“InincludeCMAKELIST”
“IndatabaseCMAKELIST”
“InmatchCMAKELIST”
“InrecordCMAKELIST”
“InspectogramCMAKELIST”
/home/lamda/soundcloud/src/include/spectogram/base/base.h
“outspectogramCMAKELIST”
-- Configuring done
CMake Error in src/CMakeLists.txt:
  Target "cmakeDemo" requires the language dialect "CXX17" (with compiler
  extensions), but CMake does not know the compile flags to use to enable it.


-- Generating done
-- Build files have been written to: /home/lamda/soundcloud/build
make: *** [cmake_check_build_system] Error 1

But somehow isn't it willing to use c++17, so I can use the filesystem library? why?