As I understand it systems programming is the priority application area for Rust, and there are plenty of projects working on OSs, embedded or other bare-metal cases, as well as interoperability with complex C codebases.

At first glance, these features look quite general to me and not particularly tied to the kernel, they are important utilities for doing this kind of programming in the real world.

I see Rust's place on low level systems programming, for everything else on userspace compiled managed languages are a much better option, systems following an architecture like Self, Inferno or Android, so I don't see a big deal with these efforts focusing on low level C like capabilities.

How does "coalesced heap construction" or "coalesced heap allocation"?

I'm probably misunderstanding the complexity of the problem, but wouldn't this be solvable by just defining the right calling convention?

"Any structures larger than x, or any structures marked with a marker type, are returned by the caller providing an outref to a buffer with correct size, and the callee directly writes the structure into that buffer."

Then you could just write normal code like

    fn initialize() -> A { 
    // the initialization code 
    }

and it would just work? And it would reduce unnecessary copies in a lot of other situations too? Given how much work has been put into this issue, and how much less convenient the proposed solutions are, I feel like I must be missing something.