`unnecessary_cfg_test`

[yoav-lavi]

What it does

Since #[test] is already implicitly #[cfg(test)], it would not be needed to use #[cfg(test)] directly on a function.

I propose this lint to catch cases of

#[cfg(test)]
#[test]
fn test() {}

Suggesting instead to either remove the cfg (for inline tests), to add it to the module itself (for inline modules, e.g. #[cfg(test)] mod test {}) or to use #![cfg(test)] at the head of the file (for test files).

Lint Name

unnecessary_cfg_test

Category

style

Advantage

Removes redundant code

Drawbacks

None that I'm aware of

Example

#[cfg(test)]
#[test]
fn test() {}

Could be written as:

// test file
#![cfg(test)]

#[test]
fn test() {}

// inline test
#[test]
fn test() {}

// inline test module
#[cfg(test)] 
mod test {
    #[test]
    fn test() {}
}

[yoav-lavi]

@xFrednet commented on Zulip that this is probably not possible to efficiently develop at the moment as cfgs are removed before Clippy sees the AST. Might be a good point of discussion for rustc to keep some sort of marker so that the information is not lost (and / or thinking about how to lint the entire AST before removal)