xrt: add new xrt_result_t error codes

* adds generic and future specific error codes

Part-of: <https://gitlab.freedesktop.org/monado/monado/-/merge_requests/2554>

src/xrt/auxiliary/util/u_pretty_print.c

@@ -228,6 +228,10 @@ u_pp_xrt_result(struct u_pp_delegate dg, xrt_result_t xret)
 	case XRT_ERROR_SYNC_PRIMITIVE_CREATION_FAILED:       DG("XRT_ERROR_SYNC_PRIMITIVE_CREATION_FAILED"); return;
 	case XRT_ERROR_IPC_SERVICE_ALREADY_RUNNING:          DG("XRT_ERROR_IPC_SERVICE_ALREADY_RUNNING"); return;
 	case XRT_ERROR_IPC_MAINLOOP_FAILED_TO_INIT:          DG("XRT_ERROR_IPC_MAINLOOP_FAILED_TO_INIT"); return;
+	case XRT_ERROR_INVALID_ARGUMENT:                     DG("XRT_ERROR_INVALID_ARGUMENT"); return;
+	case XRT_OPERATION_CANCELLED:                        DG("XRT_OPERATION_CANCELLED"); return;
+	case XRT_ERROR_FUTURE_RESULT_NOT_READY:              DG("XRT_ERROR_FUTURE_RESULT_NOT_READY"); return;
+	case XRT_ERROR_FUTURE_ALREADY_COMPLETE:              DG("XRT_ERROR_FUTURE_ALREADY_COMPLETE"); return;
 	}
 	// clang-format on
 

src/xrt/include/xrt/xrt_results.h

@@ -38,6 +38,11 @@ typedef enum xrt_result
 	 */
 	XRT_SPACE_BOUNDS_UNAVAILABLE = 3,
 
+	/*!
+	 * An (asynchronous) operation has been cancelled.
+	 */
+	XRT_OPERATION_CANCELLED = 4,
+
 	/*!
 	 * A problem occurred either with the IPC transport itself, with invalid commands from the client, or with
 	 * invalid responses from the server.
@@ -231,4 +236,19 @@ typedef enum xrt_result
 	 * The IPC server couldn't starts it mainloop.
 	 */
 	XRT_ERROR_IPC_MAINLOOP_FAILED_TO_INIT = -38,
+
+	/*!
+	 * Invalid function arguments passed in, e.g. null or out-of-range values.
+	 */
+	XRT_ERROR_INVALID_ARGUMENT = -39,
+
+	/*!
+	 * Querying result of a future before it is ready.
+	 */
+	XRT_ERROR_FUTURE_RESULT_NOT_READY = -40,
+
+	/*!
+	 * Invoking complete on an already completed future
+	 */
+	XRT_ERROR_FUTURE_ALREADY_COMPLETE = -41,
 } xrt_result_t;