Crate target_spec

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Evaluate Cargo.toml target specifications against platform triples.

Cargo supports platform-specific dependencies. These dependencies can be specified in one of two ways:

# 1. As Rust-like `#[cfg]` syntax.
[target.'cfg(all(unix, target_arch = "x86_64"))'.dependencies]
native = { path = "native/x86_64" }

# 2. Listing out the full target triple.
[target.x86_64-pc-windows-gnu.dependencies]
winhttp = "0.4.0"

target-spec provides the eval API which can be used to figure out whether such a dependency will be included on a particular platform.

use target_spec::eval;

// Evaluate Rust-like `#[cfg]` syntax.
let cfg_target = "cfg(all(unix, target_arch = \"x86_64\"))";
assert_eq!(eval(cfg_target, "x86_64-unknown-linux-gnu").unwrap(), Some(true));
assert_eq!(eval(cfg_target, "i686-unknown-linux-gnu").unwrap(), Some(false));
assert_eq!(eval(cfg_target, "x86_64-pc-windows-msvc").unwrap(), Some(false));

// Evaluate a full target-triple.
assert_eq!(eval("x86_64-unknown-linux-gnu", "x86_64-unknown-linux-gnu").unwrap(), Some(true));
assert_eq!(eval("x86_64-unknown-linux-gnu", "x86_64-pc-windows-msvc").unwrap(), Some(false));

For more advanced usage, see Platform and TargetSpec.

§Optional features

§Minimum supported Rust version

The minimum supported Rust version (MSRV) is:

  • For target-spec 3.0.x: Rust 1.66.
  • For target-spec 3.1.x: Rust 1.73.

Within the 3.x series, MSRV bumps will be accompanied by a minor version update.

To pretty-print target-spec errors, consider using the miette diagnostic library with target-spec-miette.

Re-exports§

Modules§

  • Errors returned by target-spec.

Structs§

Enums§

  • A set of target features to match.
  • A parsed target specification or triple string, as found in a Cargo.toml file.

Functions§

  • Evaluates the given spec against the provided target and returns Some(true) on a successful match, and Some(false) on a failing match.