test: build testsprite as c++ application

test/CMakeLists.txt

@@ -13,10 +13,16 @@ set(SDL3_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/..")
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/../cmake")
 
 include(CheckIncludeFile)
+include(CheckLanguage)
 include(CheckStructHasMember)
 include(CMakePushCheckState)
 include(sdlcompilers)
 
+check_language(CXX)
+if(CMAKE_CXX_COMPILER)
+    enable_language(CXX)
+endif()
+
 find_package(Python3 COMPONENTS Interpreter)
 if(NOT PYTHON3_EXECUTABLE)
     set(PYTHON3_EXECUTABLE "python3")
@@ -449,6 +455,9 @@ add_sdl_test_executable(testsoftwaretransparent SOURCES testsoftwaretransparent.
 add_sdl_test_executable(testsprite MAIN_CALLBACKS NEEDS_RESOURCES TESTUTILS SOURCES testsprite.c NAME83 sprite)
 add_sdl_test_executable(testspriteminimal SOURCES testspriteminimal.c ${icon_png_header} DEPENDS generate-icon_png_header NAME83 spritmin)
 add_sdl_test_executable(testspritesurface SOURCES testspritesurface.c ${icon_png_header} DEPENDS generate-icon_png_header NAME83 spritsrf)
+if(CMAKE_CXX_COMPILER)
+    add_sdl_test_executable(testspritecxx MAIN_CALLBACKS NEEDS_RESOURCES TESTUTILS SOURCES testsprite.cpp NAME83 spritexx)
+endif()
 add_sdl_test_executable(testpalette SOURCES testpalette.c NAME83 palette)
 add_sdl_test_executable(testtimer NONINTERACTIVE NONINTERACTIVE_ARGS --no-interactive NONINTERACTIVE_TIMEOUT 60 SOURCES testtimer.c NAME83 timer)
 add_sdl_test_executable(testurl SOURCES testurl.c NAME83 url)

test/testsprite.cpp

@@ -0,0 +1 @@
+#include "testsprite.c"

test/testutils.h

@@ -16,8 +16,16 @@
 
 #include <SDL3/SDL.h>
 
-SDL_Texture *LoadTexture(SDL_Renderer *renderer, const char *file, bool transparent);
-char *GetNearbyFilename(const char *file);
-char *GetResourceFilename(const char *user_specified, const char *def);
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern SDL_Texture *LoadTexture(SDL_Renderer *renderer, const char *file, bool transparent);
+extern char *GetNearbyFilename(const char *file);
+extern char *GetResourceFilename(const char *user_specified, const char *def);
+
+#ifdef __cplusplus
+}
+#endif
 
 #endif