Crate target_spec

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"), Ok(Some(true)));
assert_eq!(eval(cfg_target, "i686-unknown-linux-gnu"), Ok(Some(false)));
assert_eq!(eval(cfg_target, "x86_64-pc-windows-msvc"), Ok(Some(false)));

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

Structs

Platform	A platform to evaluate target specs against.
TargetSpec	A parsed target specification or triple, as found in a Cargo.toml file.

Enums

EvalError	An error that occurred during target evaluation.
ParseError	An error that occurred while attempting to parse a target specification.
TargetFeatures	A set of target features to match.

Functions

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