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").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

• custom: Adds support for custom targets via [Platform::new_custom].
• summaries: Adds the [summaries] module to enable serialization of Platform and TargetFeatures.
• proptest1: Enables support for property-based testing of Platform and TargetFeatures using [proptest].

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.

Related crates

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

Re-exports

• pub use errors::Error;

Modules

• errors
  Errors returned by target-spec.

Structs

• Platform
  A platform to evaluate target specifications against.
• TargetSpecExpression
  A target expression, parsed from a string beginning with cfg(.
• TargetSpecPlainString
  A plain string as contained within a TargetSpec::PlainString.
• Triple
  A single, specific target, uniquely identified by a triple.

Enums

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

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.