Re-evaluate policy on lowest supported Rust version

[mulkieran]

Our current development (1.79) is almost a year ahead of our lowest supported (1.71) at this time. Do we have a reason to move up and are we able to move up?

[mulkieran]

We have a lint-related reason now. It's pretty minor, though. We merged a clippy allow that would have been done nicer in a build script. Here's the PR: stratis-storage/devicemapper-rs#928 . Had we been running a newer version of Rust we would have handled that differently, by emitting instructions in build.rs: https://blog.rust-lang.org/2024/05/06/check-cfg.html.

[mulkieran]

We have a more important reason that would require us to move up to 1.77.0, since bindgen 0.70.0 emits code for libcryptsetup which wasn't part of the standard library until 1.77.0. https://doc.rust-lang.org/std/mem/macro.offset_of.html# and https://github.com/stratis-storage/libcryptsetup-rs/actions/runs/10491531137/job/29060894678?pr=348 . No sign of any action in Fedora to update bindgen to new release, but could happen any time. Note that 1.77 is only a bit more than 4.5 months back. EDIT: This information was inaccurate. bindgen supports the rust_target() method, which allows pinning the output code to a given release.