何時應(yīng)該在函數(shù)返回值上使用std :: move？在這種情況下struct Foo {};Foo meh() {  return std::move(Foo());}我很確定移動是不必要的，因為新創(chuàng)建的Foo將是一個xvalue。但在這種情況下呢？struct Foo {};Foo meh() {  Foo foo;  //do something, but knowing that foo can safely be disposed of  //but does the compiler necessarily know it?  //we may have references/pointers to foo. how could the compiler know?  return std::move(foo); //so here the move is needed, right?}我認(rèn)為需要采取行動嗎？