mbed 在线编译问题

#include "mbed.h" #include "rtos.h" DigitalOut led1(LED1); DigitalOut led2(LED2); void led2_thread(void const *args) {     while (true) {         led2 = !led2;         Thread::wait(1000);     } } int main() {     Thread thread(led2_thread);         while (true) {         led1 = !led1;         Thread::wait(500);     } } 这个导入在线编译器后，编译后Thread thread(led2_thread);提示警告，下到PC824板上直接不工作