Add static assertions for version numbers' limits

Signed-off-by: Simon McVittie <smcv@collabora.com>

src/SDL.c

@@ -62,6 +62,22 @@ extern int SDL_HelperWindowCreate(void);
 extern int SDL_HelperWindowDestroy(void);
 #endif
 
+SDL_COMPILE_TIME_ASSERT(SDL_MAJOR_VERSION_min, SDL_MAJOR_VERSION >= 0);
+/* Limited only by the need to fit in SDL_version */
+SDL_COMPILE_TIME_ASSERT(SDL_MAJOR_VERSION_max, SDL_MAJOR_VERSION <= 255);
+
+SDL_COMPILE_TIME_ASSERT(SDL_MINOR_VERSION_min, SDL_MINOR_VERSION >= 0);
+/* Limited only by the need to fit in SDL_version */
+SDL_COMPILE_TIME_ASSERT(SDL_MINOR_VERSION_max, SDL_MINOR_VERSION <= 255);
+
+SDL_COMPILE_TIME_ASSERT(SDL_PATCHLEVEL_min, SDL_PATCHLEVEL >= 0);
+#if SDL_MAJOR_VERSION < 3
+/* Limited by its encoding in SDL_VERSIONNUM */
+SDL_COMPILE_TIME_ASSERT(SDL_PATCHLEVEL_max, SDL_PATCHLEVEL <= 99);
+#else
+/* Limited only by the need to fit in SDL_version */
+SDL_COMPILE_TIME_ASSERT(SDL_PATCHLEVEL_max, SDL_PATCHLEVEL <= 255);
+#endif
 
 /* This is not declared in any header, although it is shared between some
     parts of SDL, because we don't want anything calling it without an