Platform : This commit will allow failsafe core context creation on Mac OS X.

Before this commit the default context creation in tryCreateContext
would create the OpenGL 2.1 context.After this commit by default,
the OpenGL 3.2 context is created by default, if this fails
tryCreateContext will fall back to creating a OpenGL 2.1 context.

src/Platform/Sdl2Application.cpp

@@ -111,6 +111,46 @@ bool Sdl2Application::tryCreateContext(const Configuration& configuration) {
 
     /** @todo Remove when Emscripten has proper SDL2 support */
     #ifndef CORRADE_TARGET_EMSCRIPTEN
+
+    #ifdef __APPLE__
+
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+
+    if(!(window = SDL_CreateWindow(configuration.title().data(),
+        SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
+        configuration.size().x(), configuration.size().y(),
+        SDL_WINDOW_OPENGL|flags))){
+            Error() << "Platform::Sdl2Application::tryCreateContext(): cannot create core window:" << SDL_GetError();
+            return false;
+    }
+
+    if(!(context = SDL_GL_CreateContext(window))){
+        Error() << "Platform::Sdl2Application::tryCreateContext(): cannot create core context:" << SDL_GetError() << " falling back to compatibility context.";
+        SDL_DestroyWindow(window);
+
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1);
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_COMPATIBILITY);
+
+        if(!(window = SDL_CreateWindow(configuration.title().data(),
+            SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
+            configuration.size().x(), configuration.size().y(),
+            SDL_WINDOW_OPENGL|flags))){
+                Error() << "Platform::Sdl2Application::tryCreateContext(): cannot create window:" << SDL_GetError();
+                return false;
+        }
+
+        if(!(context = SDL_GL_CreateContext(window))){
+            Error() << "Platform::Sdl2Application::tryCreateContext(): cannot create compatibility context:" << SDL_GetError();
+            SDL_DestroyWindow(window);
+            window = nullptr;
+            return false;
+        }
+    }
+
+    #else
     if(!(window = SDL_CreateWindow(configuration.title().data(),
             SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
             configuration.size().x(), configuration.size().y(),
@@ -125,6 +165,7 @@ bool Sdl2Application::tryCreateContext(const Configuration& configuration) {
         window = nullptr;
         return false;
     }
+    #endif
     #else
     context = SDL_SetVideoMode(configuration.size().x(), configuration.size().y(), 24, SDL_OPENGL|SDL_HWSURFACE|SDL_DOUBLEBUF);
     #endif