[lints] table reason

[richardscollin]

Problem

I was playing around with the new rust 1.81 lint reason feature and I noticed that the reason cannot be set in the Cargo.toml [lints] section like it can in rust code:

#![warn(clippy::shadow_unrelated, reason = "I'm afraid of shadows")]
fn main() {
    let x = 1 + 2;
    println!("{x}");

    let x = "foo bar";
    println!("{x}");
}

Proposed Solution

I would expect that I would be able to set the lint reason in the Cargo.toml like so:

[package]
name = "lint-reason-check"
version = "0.1.0"
edition = "2021"

[dependencies]

[lints.clippy]
shadow_unrelated = { level = "warn", reason = "I'm afraid of shadows" }

I'm unsure what behavior makes sense if the reason is set in both the Cargo.toml file and the rust source file. I'm also not sure if this should be a cargo issue, and rust issue, or a clippy issue.

Notes

No response

[epage]

Cargo is the appropriate place for this.

The way we currently pass [lints] to rustc, clippy, and rustdoc is insufficient to handle this. That is also true for #12534 and #13565. We need a new way to pass this information to rustc on the command line.

[epage]

Speaking of rustc's command-line, there isn't a flag for expect. I wonder if that should also be exposed within this new CLI.