Add SDL3 CMake config file (#23869)

This is the equivalent of, and heavily based on, #15987 but for SDL3.

Assuming that I've understood
#19780 (comment)
correctly, none of the old style variables are expected to be set so we
only need to provide targets. This has the benefit that it Just Works
without needing to run `emcc -sUSE_SDL=3` first to download the port.

Author: bobsayshilol

system/lib/cmake/SDL3/sdl3-config.cmake

@@ -0,0 +1,18 @@
+if(NOT TARGET SDL3::SDL3)
+  add_library(SDL3::Headers INTERFACE IMPORTED)
+  set_target_properties(SDL3::Headers PROPERTIES
+    INTERFACE_COMPILE_OPTIONS "-sUSE_SDL=3"
+  )
+
+  add_library(SDL3::SDL3-static INTERFACE IMPORTED)
+  set_target_properties(SDL3::SDL3-static PROPERTIES
+    INTERFACE_COMPILE_OPTIONS "-sUSE_SDL=3"
+    INTERFACE_LINK_LIBRARIES "-sUSE_SDL=3"
+  )
+
+  add_library(SDL3::SDL3 INTERFACE IMPORTED)
+  set_target_properties(SDL3::SDL3 PROPERTIES
+    INTERFACE_COMPILE_OPTIONS "-sUSE_SDL=3"
+    INTERFACE_LINK_LIBRARIES "-sUSE_SDL=3"
+  )
+endif()

test/cmake/find_modules/CMakeLists.txt

@@ -4,17 +4,17 @@ project(find_modules)
 add_executable(test_prog test.c)
 
 find_package(OpenGL REQUIRED)
-include_directories(${OPENGL_INCLUDE_DIR})
+target_include_directories(test_prog PRIVATE ${OPENGL_INCLUDE_DIR})
 target_link_libraries(test_prog ${OPENGL_LIBRARIES})
 message(STATUS " test: OPENGL_LIBRARIES: ${OPENGL_LIBRARIES}")
 
 find_package(OpenAL REQUIRED)
-include_directories(${OPENAL_INCLUDE_DIR})
+target_include_directories(test_prog PRIVATE ${OPENAL_INCLUDE_DIR})
 target_link_libraries(test_prog ${OPENAL_LIBRARY})
 message(STATUS " test: OPENAL_LIBRARIES: ${OPENAL_LIBRARIES}")
 
 find_package(SDL2 REQUIRED)
-include_directories(${SDL2_INCLUDE_DIRS})
+target_include_directories(test_prog PRIVATE ${SDL2_INCLUDE_DIRS})
 target_link_libraries(test_prog SDL2::SDL2)
 message(STATUS " test: SDL2_LIBRARIES: ${SDL2_LIBRARIES}")
 message(STATUS " test: SDL2_INCLUDE_DIRS: ${SDL2_INCLUDE_DIRS}")
@@ -24,3 +24,7 @@ message(STATUS " test: OpenGL::GL IMPORTED_LIBNAME: ${TEST_OPENGL_GL_LIBNAME}")
 
 get_target_property(TEST_OPENGL_GL_INCLUDES OpenGL::GL INTERFACE_INCLUDE_DIRECTORIES)
 message(STATUS " test: OpenGL::GL INTERFACE_INCLUDE_DIRECTORIES: ${TEST_OPENGL_GL_INCLUDES}")
+
+find_package(SDL3 REQUIRED)
+add_executable(test_prog_sdl3 test_sdl3.c)
+target_link_libraries(test_prog_sdl3 SDL3::SDL3)

test/cmake/find_modules/test_sdl3.c

@@ -0,0 +1,13 @@
+// Include emscripten/version.h to ensure that the in-tree
+// include directory has not been added to the include path.
+#include <emscripten/version.h>
+#include <SDL3/SDL.h>
+
+int main() {
+  int compiled = SDL_VERSION;
+  SDL_Log("SDL version: %d.%d.%d\n",
+          SDL_VERSIONNUM_MAJOR(compiled),
+          SDL_VERSIONNUM_MINOR(compiled),
+          SDL_VERSIONNUM_MICRO(compiled));
+  return 0;
+}

test/test_other.py

@@ -1081,6 +1081,8 @@ def test_cmake_find_modules(self):
     output = self.run_js('test_prog.js')
     self.assertContained('AL_VERSION: 1.1', output)
     self.assertContained('SDL version: 2.', output)
+    output = self.run_js('test_prog_sdl3.js')
+    self.assertContained('SDL version: 3.', output)
 
   def test_cmake_threads(self):
     self.run_process([EMCMAKE, 'cmake', test_file('cmake/threads')])