# Static rustc_lint_defs::builtin::UNEXPECTED_CFGS

source ·

    pub static UNEXPECTED_CFGS: &Lint

Expand description

The `unexpected_cfgs` lint detects unexpected conditional compilation conditions.

#### §Example

    rustc --check-cfg 'cfg()'

ⓘ

    #[cfg(widnows)]
    fn foo() {}

This will produce:

    warning: unexpected `cfg` condition name: `widnows`
     --> lint_example.rs:1:7
      |
    1 | #[cfg(widnows)]
      |       ^^^^^^^
      |
      = note: `#[warn(unexpected_cfgs)]` on by default

#### §Explanation

This lint is only active when `--check-cfg` arguments are being passed to the compiler and triggers whenever an unexpected condition name or value is used.

The known condition include names or values passed in `--check-cfg`, and some well-knows names and values built into the compiler.