bincode v2.0.0 error: cannot find decode_borrowed_from_slice

[BeadiestStar64]

Describe the bug
When I do a cargo build with Burn as a dependency, cargo reports that Burn Core cannot find bincode::serde.

To Reproduce

1. Execute cargo add burn --features wgpu.
2. Execute cargo test.

Expected behavior
Pass the test without any problems.

Screenshots

Desktop (please complete the following information):

• OS: Windows 11 Home 24H2
• Rust Edition: 2021

[laggui]

bincode version 2.0.0 was officially released yesterday, which introduced some breaking changes.

Burn uses 2.0.0-rc.3, but cargo dependency resolver treats pre-release versions (-rc.3) as lower priority than stable releases... so it fetches the 2.0.0 release (which is not compatible).

For the released Burn versions, please add an explicit dependency to the pre-release version in your Cargo.toml:

[dependencies]
burn = { version = "0.16.0", features = ["wgpu"] }
bincode = "=2.0.0-rc.3"
bincode_derive = "=2.0.0-rc.3"

The new bincode release also only supports 1.85 MSRV, so for now we'll have to explicitly pin the release candidate on main and eventually upgrade to the last release.

[BeadiestStar64]

Thank you so much for your detailed explanation and solution.
As you suggested, adding an explicit dependency on the pre-release version of bincode quickly resolved the issue👍

[laggui]

Re-opening in favor of #2880 since an explanation and solution has been given here.

[alessandromazza98]

is there an eta for the fix on main branch? or new release ideally.

[laggui]

For some reason cargo was not resolving to bincode v2.0 locally or on the CI so I thought the pinned rc3 had been merged, but it's still contained in another PR.

Just opened a PR for this fix specifically. Will update to 2.0 once rust 1.86 comes out because we always support current (1.85) and prev (1.84), and bincode 2.0 has MSRV 1.85.

No ETA for a release at this time, we have a couple of things we still want to do to wrap up the next release 🙂