Building GTK+ application with CMake on Windows - windows

Question

I'm trying to build a simple GTK+ app on Windows (64 bit) using CMake. I've installed everything according to the official guide.
Here's the contents of my CMakeLists.txt:
# Set project
project(gtk-test C)
cmake_minimum_required(VERSION 3.0)
# Configure project paths
set(PROJECT_SOURCE_DIR ${PROJECT_SOURCE_DIR}/src)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/bin)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/lib)
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/lib)
# Find dependencies
find_package(PkgConfig REQUIRED)
pkg_check_modules(GTK3 REQUIRED gtk+-3.0)
include_directories(${GTK3_INCLUDE_DIRS})
link_directories(${GTK3_LIBRARY_DIRS})
add_definitions(${GTK3_CFLAGS_OTHER})
set(LIBRARIES ${LIBRARIES} ${GTK3_LIBRARIES})
# Compile
add_executable(main ${PROJECT_SOURCE_DIR}/main.c)
target_link_libraries(main ${LIBRARIES})
# Messages
message(STATUS "GTK include directories: ${GTK3_INCLUDE_DIRS}")
and then I'm building the source file with the following:
cmake -Bbuild -H.
cmake --build build
Everything seems to work fine on macOS, but on Windows I keep getting the following error:
fatal error: gtk/gtk.h: No such file or directory
#include <gtk/gtk.h>
I checked the directory included by CMake and the header file is there. Also, the following command from the tutorial successfully builds the application:
gcc `pkg-config --cflags gtk+-3.0` -o main.exe main.c `pkg-config --libs gtk+-3.0`
Still, I would really love to get it working with CMake. I've been searching for the solution for hours now with no result, so any help would be highly appreciated.
Thanks in advance!
Update
Apparently, the whole problem lies within included libraries. For some reason, the line:
include_directories(${GTK3_INCLUDE_DIRS})
does not include them. I managed to fix the problem including libraries myself with -I option:
# Set project
cmake_minimum_required(VERSION 3.0)
project(gtk-test C)
# Configure project paths
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/bin)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/lib)
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/lib)
set(CMAKE_SOURCE_DIR ${CMAKE_SOURCE_DIR}/src)
# Find dependencies
find_package(PkgConfig REQUIRED)
pkg_check_modules(GTK3 REQUIRED gtk+-3.0)
link_directories(${GTK3_LIBRARY_DIRS})
add_compile_options(${GTK3_CFLAGS_OTHER})
set(LIBRARIES ${LIBRARIES} ${GTK3_LIBRARIES})
set(FLAGS "-I${GTK3_INCLUDE_DIRS}")
message(STATUS "Flags: ${FLAGS}")
string(REPLACE ";" " -I" FLAGS "${FLAGS}")
set(CMAKE_C_FLAGS ${CMAKE_C_FLAGS} ${GTK3_FLAGS} ${FLAGS})
# Compile
add_executable(main ${PROJECT_SOURCE_DIR}/main.c)
target_link_libraries(main ${LIBRARIES})
Although it seems to work, this does not look like a good solution to me.