Comment by Yoric

I co-implemented this in OCaml ~20 years ago, using no compiler magic (it did use a macro). Pretty sure that I've seen the equivalent in Haskell, too, and in variants of Scheme. Zig has it, too. And while, as you mention, the Rust implementation does use compiler magic, I'm pretty sure that it could be implemented as a macro, just more slowly.

etc.