代码如下，为什么会报错呢？

void clear(int *a)
{
	memset(a,0,sizeof(a));
}

错误信息

warning: argument to 'sizeof' in 'void* memset(void*, int, size_t)' call is the same expression as the destination; did you mean to dereference it? [-Wsizeof-pointer-memaccess]