warning: unexpected cfg condition name: rustfmt

[asomers]

The latest rustc compiler tries to detect the use of unknown #[cfg()] conditions. It's triggering in lalrpop-generated code. The easiest way to reproduce the problem is to simply run cargo check -p nobol in lalrpop's own git repo. Or, it can be reproduced by trying to compile a file like this:

grammar;

pub Num: i16 = r"[0-9]+" => i16::from_str(<>).unwrap();

Which results in the warning

warning: unexpected `cfg` condition name: `rustfmt`
  --> /usr/home/somers/src/rust/bfffs/target/debug/build/bfffs-555042f4e29eb538/out/x.rs:12:12
   |
12 | #[cfg_attr(rustfmt, rustfmt_skip)]
   |            ^^^^^^^
   |
   = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(rustfmt)");` to the top of the `build.rs`
   = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

warning: unexpected `cfg` condition name: `rustfmt`
   --> /usr/home/somers/src/rust/bfffs/target/debug/build/bfffs-555042f4e29eb538/out/x.rs:303:12
    |
303 | #[cfg_attr(rustfmt, rustfmt_skip)]
    |            ^^^^^^^
    |
    = help: consider using a Cargo feature instead or adding `println!("cargo::rustc-check-cfg=cfg(rustfmt)");` to the top of the `build.rs`
    = note: see <https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#rustc-check-cfg> for more information about checking conditional configuration

This is the rust version I'm currently using:

> rustc --version -v
rustc 1.80.0-nightly (e82c861d7 2024-05-04)
binary: rustc
commit-hash: e82c861d7e5ecd766cb0dab0bf622445dec999dc
commit-date: 2024-05-04
host: x86_64-unknown-freebsd
release: 1.80.0-nightly
LLVM version: 18.1.4

[Pat-Lafon]

This just landed on nightly right? I'm interested in fixing this(I think it exposed some other cfg issues that went undetected with cfg(feature = "test"). Ironically though, the example you included has just been fixed on the latest nightly(because of issues with rustfmt).

[asomers]

Yeah, it only started to fail sometime within the last few weeks.