[Bug c++/106166] Improve diagnostic for explicit constructor

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106166

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-07-02
     Ever confirmed|0                           |1

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Yes I've been bothered by this for a while. I think this diagnostic is
mentioned in another PR too, contrasting it to the way we display errors for
non-explicit ctors.