Remove if_chain crate now that we're on MSRV 1.88

[brannondorsey]

Completes the task originally discussed in #1806.

[brannondorsey]

@smoelius I'm curious if you have a recommended fix for the failing build as of f924fdc.

Originally I tried to fix it with a86f6b8, but that was pretty naive.

The problem as I understand it is that some of the nightly toolchains in use in this project are old enough that they require feature(let_chains) while others are new enough that they forbid you from using it. 🙃

[smoelius]

Hey, @brannondorsey. I am currrently traveling, but I will try to look at this in the next couple of days.

[brannondorsey]

No problem @smoelius. Safe travels!

[smoelius]

Sorry it took me longer than expected to get to this. Thanks again for working on this.

[smoelius]

Suggested change

#![cfg_attr(nightly, feature(let_chains))]

Please remove the above.

And please change the following line:

dylint/cargo-dylint/tests/integration/package_options.rs

Line 69 in a0b7f75

let rust_version = Version::parse(msrv::MSRV).unwrap();

to:

let rust_version = Version::parse(msrv::MSRV_PLUS_1).unwrap();

Let chains were stabilized in Rust 1.88.0. So I was confused as to why MSRV (=1.88.0) was not working. I think the reason is that MSRV_CHANNEL = nightly-2025-04-22 is when Clippy switched to version 0.1.88, not when Rust switched to 1.88.0. The latter occurred around 2025-06-23.

Anyway, when I test locally with MSRV_PLUS_1, it seems to work. Please tell me if your experience is different.

[brannondorsey]

I've applied these suggested changes, however CI tests fail here with:

 error[E0658]: `let` expressions in this position are unstable
   --> /home/runner/work/dylint/dylint/internal/src/clippy_utils/revs_no_preinstall.rs:120:20
    |
120 |                 if let Some(prev_rev) = prev_rev
    |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: see issue #53667 <https://github.com/rust-lang/rust/issues/53667> for more information
    = help: add `#![feature(let_chains)]` to the crate attributes to enable
    = note: this compiler was built on 2025-04-21; consider upgrading it if it is out of date

I think the reason is that the list::one_name_multiple_chains integration test relies on MSRV_CHANNEL (see here), which requires the let_chains feature.

You can reproduce this failing test in isolation with:

cargo test --package cargo-dylint --test integration one_name_multiple_toolchains

I previously tried to resolve this via a86f6b8 but that fails because of breaking clippy_utils changes changes on nightly.

I got a little scared off by that change. But revising it today, it looks like I can get that test to pass by bumping the MSRV nightly day by exactly one day, which resolves the error without introducing breaking API changes (see 307626d). 🥳

[brannondorsey]

This info log from rustup gives a hint as to why 307626d works...

Building dylint-template with channel `nightly-2025-04-22`
info: syncing channel updates for 'nightly-2025-04-22-aarch64-apple-darwin'
info: latest update on 2025-04-22, rust version 1.88.0-nightly (d6c1e454a 2025-04-21)

nightly-2025-04-22 actually uses a release built on 2025-04-21 (although confusingly, it does include 1.88- in the name).

[brannondorsey]

OK that resolves most of the errors and we're on to just one more failure.

https://github.com/trailofbits/dylint/actions/runs/20079593588/job/57602989209

Maybe we just need to bump MSRV_CLIPPY_UTILS_REV now?

[smoelius]

Let me please look at this some more.