Componentpedia / Listings / cfg-if

Last update: 11/08/2025

cfg-if

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

Latest version: 1.0.1 registry icon
Maintenance score
21
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 may not be safe as it has not been updated for a long 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.