Fix warnings from better precision of `dead_code` lint
Fix warnings from better precision of `dead_code` lint

The lint now ignores derived `Clone` and `Debug` implementations, as of
PR rust-lang/rust#85200, which landed a couple of days ago.

I sprinkled `#[allow(dead_code)]` in a few places; the fields are not
expected to be read since they are just part of a very specific test.

rust-lang/cargo,nipunn1313/cargo,eminence/cargo,nipunn1313/cargo,rustyhorde/cargo,nipunn1313/cargo,rust-lang/cargo,eminence/cargo,rust-lang/cargo,rustyhorde/cargo,rustyhorde/cargo,nipunn1313/cargo,eminence/cargo,rustyhorde/cargo,rust-lang/cargo,eminence/cargo