use rust 1.68 in rust-toolchain.toml

[gabydd]

fixes the problem found in #7814 (comment) which was an existing problem in helix that could occur while file-walking, this occured due to a bug in rust which was fixed and in included in the 1.68 release. This pr only updates the rust-toolchain.toml so that users building from source won't encounter this bug, but our msrv is still 1.65 which is what we check in CI. As before releases are still built with the latest rust stable so nothing needs to change there.

[pascalkuthe]

It's kind of annoying that we have to use this workaround. Maybe upstream can deal with rust-toolchain.tonl field better in the future.

There are a bunch of closed issues/PRs about automatically detecting the rust version from the rust-toolchain.tonl file but no issues about ignoring/overwriting that file. Perhaps they will be open to that

Regardless thanks for investigating!

[gabydd]

I was looking into that as well we could override the tool chain maybe: https://rust-lang.github.io/rustup/overrides.html

[pascalkuthe]

Yeah an directory overwrite would again have to be done during every CI run so it's not better than just deleting the file temporarily

[pascalkuthe]

Btw. for the release CI' doesn't that also use rustup? I think the rust-toolchain.toml file always takes precedence no matter his we configure CI.

The rust-toolchain workflow works by installing the toolchain and setting the rustup default toolchain. It does nothing soecicial so just like locally the rust-toolchain.toml file always takes priority

[pascalkuthe]

Ah nvm I mussed that the release CI does the exact same thing as this PR (just with stable jsntead if MSRV). So it's reasonable to do the same here I think

[gabydd]

yeah we remove the rust-toolchain.toml in release, also I think we can set the RUSTUP_TOOLCHAIN environment variable which takes precedence over the rust-toolchain.toml but I guess it's also fine to remove it as well

[pascalkuthe]

The env variabke would be yet another place where we would have to set the MSRV tough. I think J would prefer to just remove the file in CI.

I missed ut before but release CI already does this too :D

[the-mikedavis]

I think we actually want to keep the in-tree rust-toolchain.toml at the MSRV. It's better for local development since check/clippy will catch MSRV violations. It's a rough edge for those cargo installing from source but the bug fixed in 1.68 is an unlikely edge-case to be hit while using Helix normally: I suspect that opening a file picker at / is very rarely done. Anyways we will probably be bumping the MSRV to 1.68 soon enough: the Mozilla docs seem maybe out of date but I believe the ubuntu packages are already caught up to 1.67.