In Defense of C++

I would argue that rewrite in C++ will make it a lot better. Rust does have some nice memory safe features that are nice enough that you should question why someone did a rewrite and stuck with C++, but that C++ rewrite would fix a lot.

Fresh codebases have more bugs than mature codebases. Rewriting does not fix bugs; it is a fresh codebase that may have different bugs but extremely rarely fewer bugs than the codebase most of the bugs have been patched out of. Rewriting it in Rust reduces the bugs because Rust inherently prevents large categories of bugs. Rewriting it in C++ has no magical properties that initially writing it in C++ doesn't, especially if you weren't around for the writing of the original. Maybe if there is some especially persnickety known bug that would require a major rearchitecture and you plan to implement this architecture this time around, but that is not the modal bug, and the article is especially talking about memory safety bugs which are a totally separate kind of thing from that.

I think there is significant merit to rewriting a legacy C++ (or C) codebase in very modern C++. I've done it before and it not only greatly reduced the total amount of code but also substantially improved the general safety. Faster code and higher quality. Because both implementations are "C++", there is a much more incremental path and the existing testing more or less just works.

By contrast, my experience with C++ to Rust rewrites is that the inability of Rust to express some useful and common C++ constructs causes the software architecture to diverge to the point where you might as well just be rewriting it from scratch because it is too difficult to track the C++ code.

A rewrite of your C++0x codebase that's grown from 2009 until now will most definitely fix loads of memory bugs, since C++ has very much evolved in this area since then. The added value of the borrow checker compared with modern C++ is a lot less than compared with legacy C++.

That said, I still think it's a rather weak argument, even if we do accept that the rewrite will do most of the bug removal, since we aren't stupid and move to smart pointers, more stl usage and for each loops. "Most" is not "all".