emu_window_sdl2_vk: Use the generated SDL config

On Linux, due to the way we include SDL2 as a submodule, it makes it
difficult for us to specify which SDL_config.h we intended to include.
Before, CMake would default to the dummy one included with SDL and
ignore the generated one.

This tells CMake to use the generated one. In addition, we define
USING_GENERATED_CONFIG_H to throw an error in case the dummy config is
used by accident. Fixes Vulkan not working on Linux yuzu-cmd.

CMakeLists.txt

@@ -13,7 +13,7 @@ project(yuzu)
 option(ENABLE_SDL2 "Enable the SDL2 frontend" ON)
 CMAKE_DEPENDENT_OPTION(YUZU_USE_BUNDLED_SDL2 "Download bundled SDL2 binaries" ON "ENABLE_SDL2;MSVC" OFF)
 # On Linux system SDL2 is likely to be lacking HIDAPI support which have drawbacks but is needed for SDL motion
-option(YUZU_ALLOW_SYSTEM_SDL2 "Try using system SDL2 before fallling back to one from externals" OFF)
+CMAKE_DEPENDENT_OPTION(YUZU_USE_EXTERNAL_SDL2 "Compile external SDL2" ON "ENABLE_SDL2;NOT MSVC" OFF)
 
 option(ENABLE_QT "Enable the Qt frontend" ON)
 option(ENABLE_QT_TRANSLATION "Enable translations for the Qt frontend" OFF)
@@ -387,26 +387,20 @@ if (ENABLE_SDL2)
         add_library(SDL2 INTERFACE)
         target_link_libraries(SDL2 INTERFACE "${SDL2_LIBRARY}")
         target_include_directories(SDL2 INTERFACE "${SDL2_INCLUDE_DIR}")
+    elseif (YUZU_USE_EXTERNAL_SDL2)
+        message(STATUS "Using SDL2 from externals.")
     else()
-        if (YUZU_ALLOW_SYSTEM_SDL2)
-            find_package(SDL2 2.0.15 QUIET)
-
-            if (SDL2_FOUND)
-                # Some installations don't set SDL2_LIBRARIES
-                if("${SDL2_LIBRARIES}" STREQUAL "")
-                    message(WARNING "SDL2_LIBRARIES wasn't set, manually setting to SDL2::SDL2")
-                    set(SDL2_LIBRARIES "SDL2::SDL2")
-                endif()
+        find_package(SDL2 2.0.15 REQUIRED)
 
-                include_directories(SYSTEM ${SDL2_INCLUDE_DIRS})
-                add_library(SDL2 INTERFACE)
-                target_link_libraries(SDL2 INTERFACE "${SDL2_LIBRARIES}")
-            else()
-                message(STATUS "SDL2 2.0.15 or newer not found, falling back to externals.")
-            endif()
-        else()
-            message(STATUS "Using SDL2 from externals.")
+        # Some installations don't set SDL2_LIBRARIES
+        if("${SDL2_LIBRARIES}" STREQUAL "")
+            message(WARNING "SDL2_LIBRARIES wasn't set, manually setting to SDL2::SDL2")
+            set(SDL2_LIBRARIES "SDL2::SDL2")
         endif()
+
+        include_directories(SYSTEM ${SDL2_INCLUDE_DIRS})
+        add_library(SDL2 INTERFACE)
+        target_link_libraries(SDL2 INTERFACE "${SDL2_LIBRARIES}")
     endif()
 endif()
 

externals/CMakeLists.txt

@@ -51,7 +51,7 @@ if (NOT LIBUSB_FOUND OR YUZU_USE_BUNDLED_LIBUSB)
 endif()
 
 # SDL2
-if (NOT SDL2_FOUND AND ENABLE_SDL2)
+if (YUZU_USE_EXTERNAL_SDL2)
     if (NOT WIN32)
         # Yuzu itself needs: Events Joystick Haptic Sensor Timers Audio
         # Yuzu-cmd also needs: Video (depends on Loadso/Dlopen)

src/yuzu_cmd/CMakeLists.txt

@@ -38,6 +38,11 @@ target_include_directories(yuzu-cmd PRIVATE ${RESOURCES_DIR})
 
 target_include_directories(yuzu-cmd PRIVATE ../../externals/Vulkan-Headers/include)
 
+if (YUZU_USE_EXTERNAL_SDL2)
+    target_compile_definitions(yuzu-cmd PRIVATE -DYUZU_USE_EXTERNAL_SDL2)
+    target_include_directories(yuzu-cmd PRIVATE ${PROJECT_BINARY_DIR}/externals/SDL/include)
+endif()
+
 if(UNIX AND NOT APPLE)
     install(TARGETS yuzu-cmd RUNTIME DESTINATION "${CMAKE_INSTALL_PREFIX}/bin")
 endif()

src/yuzu_cmd/emu_window/emu_window_sdl2_vk.cpp

@@ -15,6 +15,12 @@
 #include "video_core/renderer_vulkan/renderer_vulkan.h"
 #include "yuzu_cmd/emu_window/emu_window_sdl2_vk.h"
 
+#ifdef YUZU_USE_EXTERNAL_SDL2
+// Include this before SDL.h to prevent the external from including a dummy
+#define USING_GENERATED_CONFIG_H
+#include <SDL_config.h>
+#endif
+
 // Include these late to avoid polluting everything with Xlib macros
 // Ignore -Wimplicit-fallthrough due to https://github.com/libsdl-org/SDL/issues/4307
 #ifdef __clang__