Rust is inferior to C++ for my needs. This is just a reflection on we started a large project in C++ before rust existed, and now have millions of lines. Getting Rust to work with our existing C++ is hard enough as to not be worth it. Rewriting in Rust would cost 1 billion dollars. Thus despite all the problems we have with C++ that Rust would solve, rust is inferior.
(Rust is working on their C++ interoperability story and we are making changes that will allow using Rust in the future so I reserve the right to change this story in a few years, but only time will tell)
I don't think it's a defect of the language that your particular circumstance makes it infeasible to port your project. Having a great C++ interop story would be amazing, but Rust would be decidedly less awesome if it had made concessions in that direction early on.
There's a lot of warts here, particularly around the fact that all Rust types are "trivially relocatable" in C++ parlance. At the same time, figuring out which C++ types are trivially relocatable is pretty difficult. To give you an idea of the current situation, all or most non-POD C++ types must be "pinned" on the Rust side, forcing you to deal with the rather clunky `Pin<&mut T>` API. Either that or heap-allocating all C++ types owned from Rust code. Not great.
I didn't say it was a defect. I said it made rust inferior for me. Those are different things. I don't disagree with rust reasons for making that tradeoff - but the tradeoff as a result makes rust useless for now, for me. If it works for you great.
I think the term "inferior" isn't really appropriate, then. It typically applies to the quality of the thing on its own, not its applicability outside of its stated scope.
Rust is inferior to C++ for my needs. This is just a reflection on we started a large project in C++ before rust existed, and now have millions of lines. Getting Rust to work with our existing C++ is hard enough as to not be worth it. Rewriting in Rust would cost 1 billion dollars. Thus despite all the problems we have with C++ that Rust would solve, rust is inferior.
(Rust is working on their C++ interoperability story and we are making changes that will allow using Rust in the future so I reserve the right to change this story in a few years, but only time will tell)