'undefined reference to' when using GTK with CMake - c++

Question

I'm trying to build basic GTK+ code(one of its tutorials) with CMake, but I keep getting 'undefined reference to *' where * is any GTK function that is in the code. I tried to look after guides/tutorials on this, but most of them are mostly similar to what I have.
Regular compilation from terminal works without a problem using command:
g++ ./test.cpp -o test `pkg-config --cflags --libs gtk+-3.0`
When I try using CMake my CMakeLists.txt is:
cmake_minimum_required(VERSION 3.0.2)
project(gtktest)
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})
add_executable(gtktest test.cpp)
target_link_libraries(gtktest ${GKT3_LIBRARIES})
Now cmake . seems to work without problems
cmake .
-- The C compiler identification is GNU 7.4.0
-- The CXX compiler identification is GNU 7.4.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.1")
-- Checking for module 'gtk+-3.0'
-- Found gtk+-3.0, version 3.22.30
-- Configuring done
-- Generating done
-- Build files have been written to: /home/dfdark/Desktop/gtk test
But make command after that is the problem:
make
Scanning dependencies of target gtktest
[ 50%] Building CXX object CMakeFiles/gtktest.dir/test.cpp.o
[100%] Linking CXX executable gtktest
CMakeFiles/gtktest.dir/test.cpp.o: In function `activate(_GtkApplication*, void*)':
test.cpp:(.text+0x27): undefined reference to `gtk_application_window_new'
test.cpp:(.text+0x30): undefined reference to `gtk_window_get_type'
test.cpp:(.text+0x42): undefined reference to `g_type_check_instance_cast'
test.cpp:(.text+0x51): undefined reference to `gtk_window_set_title'
test.cpp:(.text+0x56): undefined reference to `gtk_window_get_type'
test.cpp:(.text+0x68): undefined reference to `g_type_check_instance_cast'
test.cpp:(.text+0x7a): undefined reference to `gtk_window_set_default_size'
test.cpp:(.text+0x86): undefined reference to `gtk_widget_show_all'
CMakeFiles/gtktest.dir/test.cpp.o: In function `main':
test.cpp:(.text+0xcc): undefined reference to `gtk_application_new'
test.cpp:(.text+0xfb): undefined reference to `g_signal_connect_data'
test.cpp:(.text+0x100): undefined reference to `g_application_get_type'
test.cpp:(.text+0x112): undefined reference to `g_type_check_instance_cast'
test.cpp:(.text+0x126): undefined reference to `g_application_run'
test.cpp:(.text+0x135): undefined reference to `g_object_unref'
collect2: error: ld returned 1 exit status
CMakeFiles/gtktest.dir/build.make:94: recipe for target 'gtktest' failed
make[2]: *** [gtktest] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/gtktest.dir/all' failed
make[1]: *** [CMakeFiles/gtktest.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2
test.cpp code (From GTK+ tutorials)
#include <gtk/gtk.h>
static void
activate (GtkApplication* app,
gpointer user_data)
{
GtkWidget *window;
window = gtk_application_window_new (app);
gtk_window_set_title (GTK_WINDOW (window), "Window");
gtk_window_set_default_size (GTK_WINDOW (window), 200, 200);
gtk_widget_show_all (window);
}
int
main (int argc,
char **argv)
{
GtkApplication *app;
int status;
app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE);
g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
status = g_application_run (G_APPLICATION (app), argc, argv);
g_object_unref (app);
return status;
}
Is the problem messed up order of CMake's commands?

Answer 1

Use GTK in your CMakeLists.txt instead of GTK3:
cmake_minimum_required(VERSION 3.0.2)
project(gtktest)
find_package(PkgConfig REQUIRED)
pkg_check_modules(GTK REQUIRED gtk+-3.0)
include_directories(${GTK_INCLUDE_DIRS})
link_directories(${GTK_LIBRARY_DIRS})
add_definitions(${GTK_CFLAGS_OTHER})
add_executable(gtktest test.cpp)
target_link_libraries(gtktest ${GTK_LIBRARIES})

Answer 2

GTK or GTK3 is a prefix and you can use any prefix you want for example.
cmake_minimum_required(VERSION 3.0.0)
project(gtktest)
find_package(PkgConfig REQUIRED)
pkg_check_modules(HI REQUIRED gtk+-3.0)
add_executable(gtktest test.cpp)
target_include_directories(gtktest PRIVATE ${HI_INCLUDE_DIRS})
target_link_libraries(gtktest PRIVATE ${HI_LIBRARIES})
However the prefix must be the same through all the CMakeLists.txt file and you are using the prefix GTK3 but later you write GKT3_LIBRARIES