Upcoming Rust language features for kernel development

Summary

The Rust for Linux project has been good for Rust, Tyler Mandry, one of the co-leads of Rust's language-design team, said. He gave a talk at Kangrejos 2025 covering upcoming Rust language features and thanking the Rust for Linux developers for helping drive them forward. Afterward, Benno Lossin and Xiangfei Ding went into more detail about their work on the three most important language features for kernel development: field projections, in-place initialization, and arbitrary self types. Many people have remarked that the development of new language features in Rust can be quite slow, Mandry said. Partly, that can be attributed to the care the Rust language team takes to avoid enshrining bad designs. But the biggest reason is "alignment in attention". The Rust project is driven by volunteers, which means that if there are not people focusing on pushing a given feature or group of related features forward, they languish. The Rust for Linux project has actually been really helpful for addressing that, Mandry explained, because it is something that a lot of people are excited about, and that focuses effort onto the few specific things that the Linux kernel needs. Mandry then went through a whirlwind list of upcoming language features, including types without known size information, reference-counting improvements, user-defined function modifiers of the same kind as const, and more. At the end, he asked which of those were most important to Rust for Linux, and how the assembled kernel developers would prioritize them. Beyond the three features to be discussed later, Lossin said that the project definitely wanted the ability to write functions that can be evaluated at compile time (called const functions in Rust) in trait definitions. Danilo Krummrich asked for specialization, which immediately prompted an "Oh no!" from Lossin, due to the feature's nearly decade-long history of causing problems for Rust's type system. Specialization would allow two overlapping implementa...