Assigning this pointer to rvalue reference to a pointer

Question

Should the following sample compile?

struct B;
struct A
{
  A(B*&&){}
};

struct B : A
{
  B() : A(this){}
};

int main(){}

On LWS

Answer 1

Yes, that should compile.

It is incorrect to implement this as cv T* const (where cv is the cv-qualifiers for the function, if any, and T is the class type). this is not const, merely a prvalue expression of a built-in type (not modifiable).

Many people think that because you can't modify this it must be const, but as Johannes Schaub - litb once commented long ago, a much better explanation is something like this:

// by the compiler
#define this (__this + 0)

// where __this is the "real" value of this

Here it's clear that you can't modify this (say, this = nullptr), but also clear no const is necessary for such an explanation. (And the value you have in your constructor is just the value of the temporary.)