CMake can't find file or directory - c++

Question

I'm working on a CMake project with multiple subdirectories and I can't get it to work. My working directory is the following:
├───main.cpp
├───CMakeLists.txt
├───build
├───States
└───CMakeLists.txt
└───Elevator
├───CMakeLists.txt
Once I build the project, I get Elevator/Elevator.h: No such file or directory as an error. The way my project is set up, Elevator is included in States and apparently CMake isn't linking them properly.
My root CMakeLists.txt:
cmake_minimum_required(VERSION 3.21.4)
project(Test)
set(CMAKE_CPP_STANDARD 11)
set(CMAKE_CPP_STANDARD_REQUIRED True)
add_subdirectory(Elevator)
add_subdirectory(States)
add_executable(${PROJECT_NAME} main.cpp)
target_link_libraries(${PROJECT_NAME} PUBLIC Elevator States)
The one in Elevator:
set(elevator_source_files
Elevator.cpp
Elevator.h
Set.cpp
Set.h
)
add_library(Elevator ${elevator_source_files})
The CMakeLists.txt in States:
set(state_source_files
State.h
State.cpp
InitialState.h
InitialState.cpp
EmergencyState.cpp
EmergencyState.h
IdleState.h
IdleState.cpp
MaintenanceState.h
MaintenanceState.cpp
MovingState.h
MovingState.cpp
AllStates.h
FSM.h
FSM.cpp
)
add_library(States ${state_source_files})
target_include_directories(States PUBLIC ${CMAKE_CURRENT_LIST_DIR}/..)
target_link_libraries(States PUBLIC Elevator)
I'm still a novice so any help would be appreciated! It's worth noting that States.h includes Elevator with #include "Elevator/Elevator.h"
UPDATE: The project now builds and runs. I updated the CMake files in the description.

Answer 1

For #include "Elevator/Elevator.h" to work in the States library you need to include the folder containing the Elevator folder.
One way to fix this is to change
target_include_directories(States PUBLIC ${CMAKE_CURRENT_LIST_DIR})
to
target_include_directories(States PUBLIC ${CMAKE_CURRENT_LIST_DIR}
${CMAKE_CURRENT_LIST_DIR}/..)
to have CMake add the State folder and its parent to the include directories.