Check usages of undefined features

[EFanZh]

What it does

Warn usages of features that are not defined in features section of Cargo.toml and are not optional dependencies.

Lint Name

undefined-features

Category

correctness, suspicious

Advantage

• Check misspelled feature names.
• Check unused code.

Drawbacks

No response

Example

fn foo() {}

#[cfg(feature = "bar")]
fn bar() {}

If feature "bar" is not defined in Cargo.toml, the code above could be written as:

fn foo() {}

[jplatte]

Duplicate of #1614.

[epage]

Looks like there is also #11649 for this. There is also native support coming to rustc/cargo, see rust-lang/rust#82450

[Alexendoo]

Closing in favour of rust-lang/rust#82450