Updated SDL 2.0.16 headers and Mac version of libraries to fix GitHub actions

code/SDL2/include/SDL_error.h

@@ -1,6 +1,6 @@
 /*
   Simple DirectMedia Layer
-  Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org>
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
 
   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
@@ -40,84 +40,41 @@ extern "C" {
 
 
 /**
- * Set the SDL error message for the current thread.
+ *  \brief Set the error message for the current thread
  *
- * Calling this function will replace any previous error message that was set.
- *
- * This function always returns -1, since SDL frequently uses -1 to signify an
- * failing result, leading to this idiom:
- *
- * ```c
- * if (error_code) {
- *     return SDL_SetError("This operation has failed: %d", error_code);
- * }
- * ```
- *
- * \param fmt a printf()-style message format string
- * \param ... additional parameters matching % tokens in the `fmt` string, if
- *            any
- * \returns always -1.
- *
- * \sa SDL_ClearError
- * \sa SDL_GetError
+ *  \return -1, there is no error handling for this function
  */
 extern DECLSPEC int SDLCALL SDL_SetError(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) SDL_PRINTF_VARARG_FUNC(1);
 
 /**
- * Retrieve a message about the last error that occurred on the current
- * thread.
+ *  \brief Get the last error message that was set
  *
- * It is possible for multiple errors to occur before calling SDL_GetError().
- * Only the last error is returned.
+ * SDL API functions may set error messages and then succeed, so you should
+ * only use the error value if a function fails.
+ * 
+ * This returns a pointer to a static buffer for convenience and should not
+ * be called by multiple threads simultaneously.
  *
- * The message is only applicable when an SDL function has signaled an error.
- * You must check the return values of SDL function calls to determine when to
- * appropriately call SDL_GetError(). You should _not_ use the results of
- * SDL_GetError() to decide if an error has occurred! Sometimes SDL will set
- * an error string even when reporting success.
- *
- * SDL will _not_ clear the error string for successful API calls. You _must_
- * check return values for failure cases before you can assume the error
- * string applies.
- *
- * Error strings are set per-thread, so an error set in a different thread
- * will not interfere with the current thread's operation.
- *
- * The returned string is internally allocated and must not be freed by the
- * application.
- *
- * \returns a message with information about the specific error that occurred,
- *          or an empty string if there hasn't been an error message set since
- *          the last call to SDL_ClearError(). The message is only applicable
- *          when an SDL function has signaled an error. You must check the
- *          return values of SDL function calls to determine when to
- *          appropriately call SDL_GetError().
- *
- * \sa SDL_ClearError
- * \sa SDL_SetError
+ *  \return a pointer to the last error message that was set
  */
 extern DECLSPEC const char *SDLCALL SDL_GetError(void);
 
 /**
- * Get the last error message that was set for the current thread.
+ *  \brief Get the last error message that was set for the current thread
  *
- * This allows the caller to copy the error string into a provided buffer, but
- * otherwise operates exactly the same as SDL_GetError().
+ * SDL API functions may set error messages and then succeed, so you should
+ * only use the error value if a function fails.
+ * 
+ *  \param errstr A buffer to fill with the last error message that was set
+ *                for the current thread
+ *  \param maxlen The size of the buffer pointed to by the errstr parameter
  *
- * \param errstr A buffer to fill with the last error message that was set for
- *               the current thread
- * \param maxlen The size of the buffer pointed to by the errstr parameter
- * \returns the pointer passed in as the `errstr` parameter.
- *
- * \sa SDL_GetError
+ *  \return errstr
  */
 extern DECLSPEC char * SDLCALL SDL_GetErrorMsg(char *errstr, int maxlen);
 
 /**
- * Clear any previous error message for this thread.
- *
- * \sa SDL_GetError
- * \sa SDL_SetError
+ *  \brief Clear the error message for the current thread
  */
 extern DECLSPEC void SDLCALL SDL_ClearError(void);