Fixed bug 1839 - SDL2 Cmake: VIDEO_COCOA check fails on OS X; VIDEO_C…

…OCOA sources aren't compiled.

cmake/macros.cmake

@@ -63,3 +63,11 @@ macro(LISTTOSTR _LIST _OUTPUT)
     set(${_OUTPUT} "${_LPREFIX}${_ITEM} ${${_OUTPUT}}")
   endforeach()
 endmacro()
+
+macro(CHECK_OBJC_SOURCE_COMPILES SOURCE VAR)
+  set(PREV_REQUIRED_DEFS "${CMAKE_REQUIRED_DEFINITIONS}")
+  set(CMAKE_REQUIRED_DEFINITIONS "-ObjC ${PREV_REQUIRED_DEFS}")
+  CHECK_C_SOURCE_COMPILES(${SOURCE} ${VAR})
+  set(CMAKE_REQUIRED_DEFINITIONS "${PREV_REQUIRED_DEFS}")
+endmacro()
+

cmake/sdlchecks.cmake

@@ -449,11 +449,12 @@ endmacro(CheckX11)
 #
 macro(CheckCOCOA)
   if(VIDEO_COCOA)
-    check_c_source_compiles("
+    check_objc_source_compiles("
         #import <Cocoa/Cocoa.h>
         int main (int argc, char** argv) {}" HAVE_VIDEO_COCOA)
     if(HAVE_VIDEO_COCOA)
       file(GLOB COCOA_SOURCES ${SDL2_SOURCE_DIR}/src/video/cocoa/*.m)
+      set_source_files_properties(${COCOA_SOURCES} PROPERTIES LANGUAGE C)
       set(SOURCE_FILES ${SOURCE_FILES} ${COCOA_SOURCES})
       set(SDL_VIDEO_DRIVER_COCOA 1)
       set(HAVE_SDL_VIDEO TRUE)