At least for the nightly builds, you can specify a closure to run when OOM happens. The only restriction is that it cannot return, but you can "recover" from panics in the nightly standard library as well. The thinking was, I think, that in most cases the default behavior of abort is the correct behavior. Recovering from a failed malloc is really only relevant in large allocations, and there are multiple paths (including directly using __rust_allocate) to recovery in that case.

Furthermore, keep in mind that the _pure language_ Rust has no concept of dynamic allocation (apart from "language elements" like __rust_allocate, which are kind of like a pre-linker).