CMake, SDL on Mac OS X, "can't find -lSDLmain" - cmake

Question

Following the instructions here, I've set up a CMakeLists.txt:
Find_Package (SDL REQUIRED)
Find_Package (SDL_image REQUIRED)
link_libraries (
${SDL_LIBRARY}
${SDLIMAGE_LIBRARY}
SDLmain
)
When running cmake, I get the following error:
ld: library not found for -lSDLmain
collect2: error: ld returned 1 exit status
make[2]: *** [src/GameOfLife] Error 1
Running g++ by hand gives the same error:
$ g++-4.7 -std=c++0x ../src/*.cpp -lSDLmain
ld: library not found for -lSDLmain
How do I fix this?

Answer 1

make doesn't know where to find SDLmain; I need to link to the directory using link_directory in `CMakeLists.txt.
Running
$ g++-4.7 -std=c++0x ../src/*.cpp `sdl-config --libs`
works fine, so I've clearly got SDL installed correctly. Checking the output of sdl-config --libs:
$ sdl-config --libs
-L/opt/local/lib -lSDLmain -lSDL -Wl,-framework,Cocoa
So the thing that's not in the CMakeLists.txt is the -L/opt/local/lib. That should be added into the CMakeLists.txt using link_directory:
link_directories( /opt/local/lib )
And then cmake runs fine.