This is a tracking issue for the RFC "A portability lint" (rust-lang/rfcs#1868). **Steps:** - [ ] Implement the RFC (cc @rust-lang/compiler -- can anyone write up mentoring instructions?) - [ ] Adjust documentation ([see instructions on forge][doc-guide]) - [ ] Stabilization PR ([see instructions on forge][stabilization-guide]) [stabilization-guide]: https://forge.rust-lang.org/stabilization-guide.html [doc-guide]: https://forge.rust-lang.org/stabilization-guide.html#updating-documentation **Unresolved questions:** - [ ] It's not clear what the story should be for a library like `libc`, which currently involves intricate uses of `cfg`. We should have some idea for how to approach such cases before landing the RFC.