c++ - 重新分配std::unique_ptr时是否释放内存？

Question

给定以下内容:

{
    std::unique_ptr<char[]> foo;
    foo = std::make_unique<char[]>(100);
    foo = std::make_unique<char[]>(200);
}

在第二次调用中重新分配foo时，第一次调用make_unique分配的内存是否被释放？

Answer 1

此代码没有泄漏。从其他分配给它的operator=转移所有权时，std::unique_ptr的 Deleter 将调用现有内存的delete[](在本示例中为unique_ptr)。
每个cppreference:
std::unique_ptr<T,Deleter>::operator=

Transfers ownership from r to *this as if by calling reset(r.release()) followed by an assignment of get_deleter() from std::forward<E>(r.get_deleter()).

std::unique_ptr<T,Deleter>::reset

Given current_ptr, the pointer that was managed by *this, performs the following actions, in this order:

• Saves a copy of the current pointer old_ptr = current_ptr
• Overwrites the current pointer with the argument current_ptr = ptr
• If the old pointer was non-empty, deletes the previously managed object
  if(old_ptr) get_deleter()(old_ptr)