Explicitly defaulted move constructor

Question

According to the c++11 standard a default move constructor is only generated if:

• X does not have a user-declared copy constructor, and
• X does not have

Answer 1

Yes, you can always explicitly invoke the default generation for functions that can be automatically generated with = default. That's what the syntax is for.

Answer 2

The motivation for that rule is that if the default copy constructor doesn't work for your class, then chances are the default move constructor won't work either (rule of 5, or whatever we're up to in C++11). So yes, you can explicitly default it, on your honor as a programmer that it'll work.

In your example code you could instead remove the copy constructor, since it does the same as the default.