The Tor Project is switching to Rust

Complete rewrites are always a bad idea ... [mutters of agreement] ... except in Rust! [cheering]

Complete rewrites have been done before. They're not impossible tasks. C to C++ (like with fish), C++ to Rust (fish again, Tor, etc), Java to C# (something I've seen), C# to C++ (evernote), Blender Game Engine to Godot (many small cases), Godot to Lumberyard (something I've seen), Unity to Godot (many small cases), etc. And there are all the myriad rewrites within the same language, or across major breaking changes (like Python 2 to Python 3).

I think "you should never do a full rewrite" is something of a reactionary response to the juvenile idea new devs and interns get every now and then. But sometimes, a rewrite really is a good idea.

But in this case, per the announcement ( https://blog.torproject.org/announcing-arti/ ), the reasons are pretty convincing. The major reasons are, unsurprisingly, all around memory safety.

The issue is that every other week there is a rewrite of something in Rust. I just do an eyeroll whenever I see that yet another thing is being rewritten in Rust.

I've tried compiling large projects in Rust in a VM (8GB) and I've run out of memory whereas I am sure a C/C++ large project of a similar size wouldn't run out of memory. A lot of this tooling I had to compile myself because it wasn't available for my Linux distro (Debian 12 at the time).

A lot of the tooling reminds me of NPM, and after spending a huge amount of my time fighting with NPM, I actually prefer the way C/C++/CMake handles stuff.

I also don't like the language. I do personal stuff in C++ and I found Rust really irritating when learning the language (the return rules are weird) and just gave up with it.

> whereas I am sure a C/C++ large project of a similar size wouldn't run out of memory

This is a common issue on large C++ projects for users with limited resources. You typically have to tinker with build settings and use a different linker etc.. to get the project building without OOMing.

> A lot of the tooling reminds me of NPM

My feeling is that you'd have the same criticism about a lot of other modern ecosystems because they allow you to pull dependencies easily. With things like vcpkg, that's also possible in C++ but even without it: nothing stops the same behavior of importing "random" code from the internet.