This is phrased in a way that’s a bit more extreme than in reality. Some new features are in the process of being added.

> Why wasn't this possibility factored in from the beginning?

So, there’s a few ways to talk about this. The first is… it was! Rust has three major layers to its standard library: core, alloc, and std. core, the lowest level, is a freestanding library. Alloc introduces memory allocations, and std introduces stuff that builds on top of OS functionality, like filesystems. What’s going on here is the kernel wanting to use the alloc layer in the kernel itself. So it’s naturally a bit higher level, and so needs some more work to fit in. Just normal software development stuff.

Why didn’t alloc have fallible APIs? Because of Linux, ironically. The usual setup there means you won’t ever observe an allocation failure. So there hasn’t been a lot of pressure to add those APIs, as they’re less useful then you might imagine at first. And it also goes the other way; a lot of embedded systems do not allocate dynamically at all, so for stuff smaller or lower level than Linux, there hasn’t been any pressure there either.

Also, I use the word “pressure” on purpose: like any open source project, work gets done when someone that needs a feature drives that feature forward. These things have been considered, for essentially forever, it’s just that finishing the work was never prioritized by anyone, because there’s an infinite amount of work to do and a finite number of people doing it. The Rust for Linux folks are now those people coming along and driving that upstream work. Which benefits all who come later.