Repo move to MSRV 1.85 breaks `rust-gpu`

[LegNeato]

Description
A recent changed bumped MSRV to 1.85 (#7218), even though >1.83 was all that was required (according to that PR).

Going to 1.85 breaks rust-gpu as we are on nightly-2024-11-22 (~1.84). We have a ton of compiler work to port forward on our end (Rust-GPU/rust-gpu#182), so it won't happen before the next wgpu release. This means people using rust-gpu will not be able to use wgpu / will have to pin to an old version.

We'd love it if you could stay with 1.84 until you absolutely need 1.85.

[LegNeato]

Note that if rust-gpu folks are stuck on older version of wgpu they won't get my fix from 10cd1cc. Without that fix certain spirv fails in Naga. In one of our test projects porting shadertoys, 5/27 shaders hit that naga bug.

[ErichDonGubler]

@cwfitzgerald: I don't think we have anything that's reliant on Rust 1.85 specifically? In which case, downgrading doesn't sound too bad.

[cwfitzgerald]

Yeah I don't think there's anything, we haven't turned on the 2024 edition, I don't think. Let's do it.

[cwfitzgerald]

Could you also include a link to where we can see rust-gpu's current toolchain version, so we don't have this issue again.

[LegNeato]

Awesome! Here is the toolchain file with the version: https://github.com/Rust-GPU/rust-gpu/blob/main/rust-toolchain.toml

[LegNeato]

(we're hoping to track nightly, and we were there during 1.84, but then got hit with some major rustc changes that slowed us down from forward-porting).