typos inside cfg macros go undetected

[JOE1994]

The below program has typos inside the cfg macro call.
(feeture instead of feature)

The below program compiles without any errors, and clippy also does not print any warnings.

pub fn main() {
    if cfg!(feeture="EXT1") {
        println!("EXTRA FEATURE1 ADDED");
    }
    #[cfg(feeture="EXT2")] {
        println!("EXTRA FEATURE2 ADDED");
    }
}

cfg macro seems to be a compiler built-in macro (source code not available?).
I found this issue while debugging my Rust code.

[mati865]

Only the "enabled" code is being checked by rustc. You should get what you expect by pressing --all-features argument to Cargo.

[JOE1994]

I apologize for not phrasing the issue well.. I am aware that only the enabled code is checked by rustc.
The issue I wanted to talk about was that feeture is an invalid configuration option, but neither rustc nor clippy complains about it. I think either clippy or rustc could print a warning that the given configuration option feeture is not a valid one.

[flip1995]

A lint with a whitelist of possible configurations would be possible. The problem is, that you can pass anything as a config through --cfg, so with rustc --cfg 'feeture="EXT1"' main.rs the code would be totally valid.

[JOE1994]

@flip1995 I see.. Can we keep this issue open for a bit to get others' feedback also? I'm curious how others would think of this issue 😃

[vallentin]

I'd say, have Clippy produce a warning if there's a high similarity. So if feeture is used, then Clippy should say "Are you sure you didn't mean 'feature'?", since they're highly similar.

Same with say target_familly (double L) or target_pointer_with (missing d).

[flip1995]

We already do something similar with unknown_clippy_lints, so this should be quite easy to implement. We'd need a list of config options though.