I wonder if they ever considered a table-driven approach for `#[derive(Debug)]`, as `facet` [1] does. That would have been my first instinct for something this formulaic where binary size and compilation time matter more than execution speed. But my impression is facet hasn't quite realized its promise on those fronts, so maybe the table-driven approach in std was similarly tried and rejected.
[1] https://crates.io/crates/facet