Compilation currently elicits a deprecation warning:
warning: `#[derive]` for custom traits is deprecated and will be removed in v1.15. Prefer using procedural macro custom derive
108 | #[derive(FromForm)]
Not much to do about this except wait for Rocket to move forward, I think.
FWIW, I don't get this deprecation warning. Perhaps I have newer versions of dependencies.
Resolved by commit 6c965e1; require newer version of Rocket in Cargo.toml.