cfg_version - The Rust Unstable Book

# `cfg_version`

The tracking issue for this feature is: #64796

The `cfg_version` feature makes it possible to execute different code depending on the compiler version.

## Examples

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

    fn main() {
    #[cfg(version("1.42"))]
    fn a() {
        // ...
    }

    #[cfg(not(version("1.42")))]
    fn a() {
        // ...
    }

    fn b() {
        if cfg!(version("1.42")) {
            // ...
        } else {
            // ...
        }
    }
    }