Fix nightly tests

[mladedav]

Motivation

The diagnostic_namespace was stabilized in nightly 1.78 and gives warnings. Some trybuild tests were broken.

Solution

The diagnostic_namespace feature was removed and tests were updated automatically.

[jplatte]

Thanks!

[jplatte]

You'll have to bump the nightly version in the GitHub actions workflow file to fix CI.

[mladedav]

Fixed.

I thought it pulled latest nightly (since I didn't find any version in the CI file) and I thought that's why I saw breakage in the other PR. Turns out there were just actual errors and when I tried to run the tests locally I must have ran them from the parent directory so the rust-toolchain file was ignored.

[tisonkun]

cc @jplatte Now with an earlier nightly toolchain I got:

error[E0658]: `#[diagnostic]` attribute name space is experimental
   --> /Users/tison/.cargo/registry/src/index.crates.io-6f17d22bba15001f/axum-0.7.5/src/handler/mod.rs:130:5
    |
130 |     diagnostic::on_unimplemented(
    |     ^^^^^^^^^^
    |
    = note: see issue #111996 <https://github.com/rust-lang/rust/issues/111996> for more information
    = help: add `#![feature(diagnostic_namespace)]` to the crate attributes to enable

[toolchain]
channel = "nightly-2023-12-19"

Is it possible to switch the feature gate by different nightly toolchain? Or how can I work around this compile error.

Bump nightly toolchain can be a significant change for our project (new ICEs, features incompatible, although we'll do it sooner or later, but I'm trying not to couple everything. I'm bumping axum from 0.6 to 0.7 now)

[tisonkun]

I use axum = { version = "=0.7.4" } to pin on an earlier axum version for now.

[jplatte]

Is it possible to switch the feature gate by different nightly toolchain? Or how can I work around this compile error.

I think it's possible but I'd rather not. Instead, we can have an explicit feature to turn that attribute on. I'm thjnking something like msrv1.80 (if that's the right version, with a - instead of . if necessary).

For now, you can pin the version. Also I would recommend checking a lockfile into git when you are using nightly.