Fix Clippy and CI on current

[meditationmind]

Fixed Clippy and MSRV CI errors on current.

[meditationmind]

Hope this was the right way to approach this.

The rustc-hash change is to preserve MSRV (2.1.2 bumps MSRV to 1.77). reqwest started pulling in a copy of hyper-rustls that breaks MSRV (0.27.8 bumps MSRV to 1.85), so I added the compatible version to the rustls_backend feature. That broke the minimal versions CI, so I also added the minimum version of hyper-util to the feature to fix that.

[mkrasnitski]

Our approach to supporting an MSRV as old as 1.74 is more hands off - we maintain a list of locked versions in .github/workflows/ci.yml which allows the MSRV job to succeed, and don't claim to support building with the MSRV out of the box without those version pins. I tested on my own fork, and seems like adding the following pins is sufficient to build:

cargo update hyper-rustls@0.27 --precise 0.27.7
cargo update rustc-hash --precise 2.1.1

The changes to Cargo.toml itself aren't necessary.

[meditationmind]

Ah, yes, that's a much better solution! I knew Poise used the MSRV-specific Cargo.lock, but I hadn't noticed the pins in the workflow file for Serenity. Thanks!

Unfortunately, something seems to have changed in nightly over the past few days, and Clippy is now complaining about the visibility of error::Result and error::Error.

error[E0365]: `Result` is only public within the crate, and cannot be re-exported outside
   --> src/lib.rs:185:9
    |
185 |         model::prelude::*,
    |         ^^^^^^^^^^^^^^^^^ re-export of crate public `Result`
    |
    = note: consider declaring type or module `Result` with `pub`

Even though they're public, they have a pub use in internal::prelude, which is pub(crate), and that seems to be causing issues since it's included in model::prelude. I'm assuming the error module has been intentionally kept private to allow for controlling where and how Result and Error are exported. I tried adjusting visibility in several places, but all of the re-exporting via various preludes is a bit of a maze and I keep running into new errors.

I've set this back to draft for now. Any advice would be appreciated.

[mkrasnitski]

This is in fact a rustc bug regressed in the newest nightly, and I used cargo bisect-rustc to bisect to rust-lang/rust#156014. Trying to write a minimal repro atm, but not having any luck.

[meditationmind]

Wow, thanks for the bisect tip. I spent a while manually combing through PRs trying to find the source (without much success).