Undefined symbol when creating a shared object with SDL2

Question

I'm trying to encapsulate some SDL2 functions into my own class. I'm working with C++ and compiling with g++.

Here's my error:

I'm creating a .so library with the following Makefile

NAME        =   arcade_sdl2.so

SRC         =   sdl2.cpp    \
                encapsulate/encapsulate.cpp

OBJ         =   $(SRC:.cpp=.o)

CFLAGS      =   -Wall -Wextra -Werror -fPIC

LIB_SDL2    =   -lSDL2 -lSDL2_ttf -lSDL2_image -lSDL2_mixer

$(NAME):    $(OBJ)
            g++ -c $(CFLAGS) $(SRC) $(LIB_SDL2)
            g++ -shared -o $(NAME) $(OBJ)
            mv $(NAME) ../../lib/

all:        $(NAME)

clean:
            rm -f $(OBJ)

fclean:     clean
            rm -rf ../../lib/$(NAME)

re:         fclean all

.PHONY:     all clean fclean re

Then, in my class destructor, I need to call my member functions which are "MYSDL::SDL_DestroyWindow()" and "MYSDL::SDL_Quit()". To do so, I've simply returned the associated function from SDL2 lib:

void MYSDL::sdl_DestroyWindow(SDL_Window *target)
{
    SDL_DestroyWindow(target);
}

and

void MYSDL::sdl_Quit(void)
{
    SDL_Quit();
}

No error occurs during compilation, as my executable "arcade" is generated. But when i want to execute it in order to load my "arcade_sdl2.so" lib, I got the following error.

Cannot open library: lib/arcade_sdl2.so: undefined symbol: SDL_DestroyWindow

Does anyone has an idea about what to do now ?

Answer 1

From @HolyBlackCat,

I used the flags for SDL2 when i was compiling, but not linking.

I needed to transform my Makefile from :

$(NAME):    $(OBJ)
            g++ -c $(CFLAGS) $(SRC) $(LIB_SDL2)
            g++ -shared -o $(NAME) $(OBJ)
            mv $(NAME) ../../lib/

to

$(NAME):    $(OBJ)
            g++ -c $(CFLAGS) $(SRC)
            g++ -shared -o $(NAME) $(OBJ) $(LIB_SDL2)
            mv $(NAME) ../../lib/