可能是未定义的行为（在这种情况下，因为您正在访问未初始化的对象），因为 a 在 A :: _ b $之前被初始化c $ c>。

It's not possible, it's undefined behavior (in this case, because you're accessing an uninitialized object) because a is initialized before A::_b.

查找静态初始化顺序失败。您不会收到任何错误，因为在这种情况下，有99％的情况会发生，这很容易诊断。

Look up static initialization order fiasco. You don't get an error because 99% of the times this happens, it's not easily diagnosable.