[correct_horse]

I haven't found a good solution to a fallible constructor without exceptions. You might want this if you have a C++ wrapper around a file or some other OS primitive. I would love some allowance for constructors returning std::optional. One problem with this is that child classes' constructors would have to return optional too or else they might throw an exception when they call optional::value.

[varajelle]

Don't write faillible constructor. Instead, you can write a static method that returns a std::optional, for example.

[jcelerier]

That does not work for data members, unless you are willing to have the entirety of your software wrapped and unwrapped in optionals up to main, which looks pretty much like what people had in the 70s and thought : "okay, maybe there is a language feature we could have to abstract that repetitive mess"

[varajelle]

Just have the non-throwing private constructor take the data member by rvalue reference and move them in place. This works in practice for so many projects that do C++ without exceptions.

[jcelerier]

But then you loose so many features of C++. Can't have aggregates anymore since everything needs private constructors -> more code -> more bugs.

Each possible contructor now needs a matching static method.

Can't put things in standard containers unless you rewrite all copy / move contructors (and you didn't forget to mark your move constructor noexcept, did you ?).

What happens when you have classes with more than 3 members ? Constructors with 12 arguments ? That's unambiguously terrible, and does not even save you from exceptions coming from C++ itself.

If 79% of surveyed C++ projects can use exceptions (https://www.jetbrains.com/lp/devecosystem-2020/cpp/), likely so can you.