Clarify MSVC-only bundled SDL support

CMakeLists.txt

@@ -7,10 +7,18 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin")
 
-option(MOTHERLOAD_USE_BUNDLED_WINDOWS_SDL "Use the bundled prebuilt SDL packages on Windows" ON)
+option(MOTHERLOAD_USE_BUNDLED_WINDOWS_SDL "Use the bundled prebuilt SDL packages for MSVC builds on Windows" ON)
 option(MOTHERLOAD_ENABLE_WARNINGS "Enable compiler warnings" ON)
 
-if(WIN32 AND MOTHERLOAD_USE_BUNDLED_WINDOWS_SDL)
+if(WIN32 AND MOTHERLOAD_USE_BUNDLED_WINDOWS_SDL AND NOT MSVC)
+    message(FATAL_ERROR
+        "MOTHERLOAD_USE_BUNDLED_WINDOWS_SDL=ON only supports MSVC/Visual Studio builds. "
+        "The bundled SDL package in Libraries/ is the SDL2 Visual C++ build, not a MinGW build. "
+        "For CLion/MinGW, disable MOTHERLOAD_USE_BUNDLED_WINDOWS_SDL and use MinGW-compatible SDL packages instead."
+    )
+endif()
+
+if(MSVC AND MOTHERLOAD_USE_BUNDLED_WINDOWS_SDL)
     list(PREPEND CMAKE_PREFIX_PATH
         "${CMAKE_SOURCE_DIR}/Libraries/SDLMain/SDL2-2.26.3/cmake"
         "${CMAKE_SOURCE_DIR}/Libraries/SDLImage/SDL2_image-2.6.3/cmake"
@@ -134,6 +142,11 @@ target_include_directories(Motherload
         "${CMAKE_SOURCE_DIR}/Game"
         "${CMAKE_SOURCE_DIR}/Engine"
 )
+
+if(TARGET SDL2::SDL2main)
+    target_link_libraries(Motherload PRIVATE SDL2::SDL2main)
+endif()
+
 target_link_libraries(Motherload
     PRIVATE
         Engine
@@ -143,10 +156,6 @@ target_link_libraries(Motherload
         SDL2_mixer::SDL2_mixer
         SDL2_ttf::SDL2_ttf
 )
-
-if(TARGET SDL2::SDL2main)
-    target_link_libraries(Motherload PRIVATE SDL2::SDL2main)
-endif()
 motherload_enable_warnings(Motherload)
 
 source_group(TREE "${CMAKE_SOURCE_DIR}" FILES ${ENGINE_SOURCES} ${GAME_SOURCES})