1986626 - Update minimum Rust version to 1.87

Status: NEW

(Firefox Build System :: Toolchains, task)

Description

[Kagami Rosylight [:saschanaz] (they/them)]

Rust 1.85 stabilized edition 2024 which some libraries started to use, e.g. jxl-rs in bug 1986393.

Comment 1

[Kagami Rosylight [:saschanaz] (they/them)]

We have 1.86 already in builders, does that mean we can/should go straight to 1.86?

Comment 2

[Kagami Rosylight [:saschanaz] (they/them)]

I'm told that 1.87 is the actual minimum supported version for safe architecture intrinsics.

Comment 3

[Kagami Rosylight [:saschanaz] (they/them)]

(Also told that they can work it around to make it work for 1.85, if 1.87 doesn't work for us anytime soon)

Comment 4

[Kagami Rosylight [:saschanaz] (they/them)]

https://treeherder.mozilla.org/jobs?repo=try&revision=b3e4a216e3310662feded2ca3ae4f080645c84bd

[task 2025-09-03T08:56:19.742+00:00] 08:56:19    ERROR -  error[E0658]: `let` expressions in this position are unstable
[task 2025-09-03T08:56:19.742+00:00] 08:56:19     INFO -     --> /builds/worker/checkouts/gecko/third_party/rust/jxl/src/api/color.rs:758:12
[task 2025-09-03T08:56:19.742+00:00] 08:56:19     INFO -      |
[task 2025-09-03T08:56:19.742+00:00] 08:56:19     INFO -  758 |         if let JxlColorEncoding::XYB { rendering_intent } = self
[task 2025-09-03T08:56:19.742+00:00] 08:56:19     INFO -      |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[task 2025-09-03T08:56:19.742+00:00] 08:56:19     INFO -      |
[task 2025-09-03T08:56:19.742+00:00] 08:56:19     INFO -      = note: see issue #53667 <https://github.com/rust-lang/rust/issues/53667> for more information

That's 1.88+...

Comment 5

[Martin Bruse]

Any idea when this might be fixed (or verified to not be fixed, so we can work around it)?

Most of the other issues blocking the Rust JXL integration are now fixed, this is one of the stragglers :D