Make copy constructors explicit

[IAmNotHanni]

https://en.cppreference.com/w/cpp/language/explicit

[IAmNotHanni]

https://www.youtube.com/watch?v=5wJ-jKK_Zy0

[IAmNotHanni]

https://www.youtube.com/watch?v=Q4SXFkTzD28

[IAmNotHanni]

I will close this since I found that general rule of thumb:

Don’t make your copy constructor explicit unless you have a very good reason — and if copying is unsafe, prefer delete over explicit.

So I don't think it's worth it at all in our case.