Componentpedia / Listings / cfg-if

Last update: 16/06/2025

cfg-if

A if/elif-like macro for Rust #[cfg] statements

Latest version: 1.0.1 registry icon
Maintenance score
51
Safety score
100
Popularity score
78
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Security
  Vulnerabilities
Version Suggest Low Medium High Critical
1.0.1 0 0 0 0 0
1.0.0 0 0 0 0 0
0.1.10 0 0 0 0 0
0.1.9 0 0 0 0 0
0.1.8 0 0 0 0 0
0.1.7 0 0 0 0 0
0.1.6 0 0 0 0 0
0.1.5 0 0 0 0 0
0.1.4 0 0 0 0 0
0.1.3 0 0 0 0 0
0.1.2 0 0 0 0 0
0.1.1 0 0 0 0 0
0.1.0 0 0 0 0 0

Stability
Latest release:

1.0.1 - This version is safe to use because it has no known security vulnerabilities at this time. Find out if your coding project uses this component and get notified of any reported security vulnerabilities with Meterian-X Open Source Security Platform

Licensing

Maintain your licence declarations and avoid unwanted licences to protect your IP the way you intended.

Apache-2.0   -   Apache License 2.0

Not a wildcard

Not proprietary

OSI Compliant

MIT   -   MIT License

Not a wildcard

Not proprietary

OSI Compliant

cfg-if

Documentation

A macro to ergonomically define an item depending on a large number of #[cfg] parameters. Structured like an if-else chain, the first matching branch is the item that gets emitted.

[dependencies]
cfg-if = "1.0"

Example

cfg_if::cfg_if! {
    if #[cfg(unix)] {
        fn foo() { /* unix specific functionality */ }
    } else if #[cfg(target_pointer_width = "32")] {
        fn foo() { /* non-unix, 32-bit functionality */ }
    } else {
        fn foo() { /* fallback implementation */ }
    }
}

fn main() {
    foo();
}

The cfg_if! block above is expanded to:

#[cfg(unix)]
fn foo() { /* unix specific functionality */ }
#[cfg(all(target_pointer_width = "32", not(unix)))]
fn foo() { /* non-unix, 32-bit functionality */ }
#[cfg(not(any(unix, target_pointer_width = "32")))]
fn foo() { /* fallback implementation */ }

License

This project is licensed under either of

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in cfg-if by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.