coverage_attribute - The Rust Unstable Book

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# `coverage_attribute`

The tracking issue for this feature is: #84605

The `coverage` attribute can be used to selectively disable coverage instrumentation in an annotated function. This might be useful to:

- Avoid instrumentation overhead in a performance critical function
- Avoid generating coverage for a function that is not meant to be executed, but still target 100% coverage for the rest of the program.

## Example

    #![allow(unused)]
    #![feature(coverage_attribute)]

    fn main() {
    // `foo()` will get coverage instrumentation (by default)
    fn foo() {
      // ...
    }

    #[coverage(off)]
    fn bar() {
      // ...
    }
    }