We use conditional compilation in a lot of places (eg the fuzzing cfg flag is standard to conditionally compile when fuzzing in the rust-fuzz ecosystem) and have a hard rule against unnecessary build.rss (as running build-time code is a red flag when auditing a crate and requires special care). Latest rustc nightly now generates a huge pile of warnings encouraging us to add a build.rs to make them go away, which isn't really acceptable. It seems this is encouraging bad practice to respond to a common practice - is there some way to just list fuzzing and some other super common flags and allow those?