I think there are a few places were Rust didn't get it quite right, but this seems like a weird example. The 32 length limit is a temporary limitation, not a corner that Rust is painted into. Indeed, my understanding is that the limitation at this point is being maintained artificially due to an overabundance of caution (via https://doc.rust-lang.org/std/array/trait.LengthAtMost32.htm... ). That's not WTF, that's just TODO.