DIP 1018--The Copy Constructor--Formal Review

[Olivier FAURE]

On Monday, 25 February 2019 at 20:41:58 UTC, Paolo Invernizzi 
wrote:
> Honestly, I've not understood the rationale or the covered use 
> case in letting the copy ctor mutate the ref source 
> parameters...
> Sincerely, without polemical intent.
>
> - P

For the same reason C++'s std::shared_pointer uses a non-const 
copy constructor.