head const (again), but for free?

[jmh530]

On Wednesday, 13 January 2021 at 22:15:59 UTC, Q. Schroll wrote:
> [snip]
>
> int* q = &i;
> head_immutable(int*)* qq = &p; // error, *qq could change 
> through q.
>
> Head immutable is more restrictive than head const, obviously.

Should that last head_immutable be &q instead of &p?

I liked Ola's description, but this one works through the basics 
in a way that really helps. So thanks.