std :: basic_string是否正式具有隐式生成的move构造函数？

Question

I'm aware that std::basic_string in practice supports move semantics, but the rvalue reference argument constructor I find in C++11 looks like this in the class definition:

C++11 §21.4/5 :

 basic_string(basic_string&&, const Allocator&); 

Then in the detailed discussion it's again shown without a default for the allocator argument:

C++11 §21.4.2/17 :

 basic_string(basic_string&& str, const Allocator& alloc); 

Disregarding obvious intent that the class should be movable, does the class then formally have an implicitly generated move constructor?

Answer 1

No, it's not implicit, but explicit. Also in C++11 21.4/5 is

basic_string(basic_string&& str) noexcept;