[__float]

If you consider the context of Carbon (Google having a _lot_ of C++), solving for "interop with C++ is hard" might be considered worth the price.

Whether that's true in practice...? I guess we'll need a few more years to tell.

[staticassertion]

Of course, that's why they're building it. They're solving a very specific, niche, hard problem. It would make no sense for other languages, which want to solve more general problems, to tackle C++ interop over C.

[olliej]

I do think this is very much a google project specifically because they have a lot of C++ and recognize that there needs to be a path to a memory safe environment, and that is why this project exists.

But I don't think the goal is inherently wrong, nor do I think it's niche - there is a lot of C++ in the world, and much of it would benefit from being memory safe. A lot of the largest projects and certainly many of the most heavily used software projects are written in C++. I think you'd agree that having them no longer be be trapped in a memory unsafety tarpit would be a Good Thing.

Let's imagine someone came out with a magic C++ compiler that had 100% source and ABI compatibility and had no performance costs, but was completely memory safe - remember "magic". You'd obviously expect, if not demand, that every C++ project switch to that magic compiler. So let's imagine we're on a scale from 1 to 10, where 1 is the memory safety of current compilers and 10 is our magic clearly impossible one. Obviously every step we can go towards 10 is great, but is going to come with trade offs in adoption cost. So on another 1 to 10 scale where 1 is rewriting in some other random language (rust, etc) and 10 is your current compiler, then you want the new language to be as close to 10 as possible. One thing you could do is build all your code with ASAN or a similar mechanism, that would have low adoption cost, a dramatic improvement in runtime safety, but a huge performance cost (time for another 1 to 10 scale?).

Carbon appears to be an attempt to design a language with a reasonably high score in all of the scales - no 10s, but mostly 7s or something. I personally think that there are things we could do to C++ that would make a meaningful improvement to safety without having the solution be "rewrite in other language", but I won't fault a project saying "we'll support incremental adoption" as their adoption path in exchange for stronger safety.