target_spec/platform.rs
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// Copyright (c) The cargo-guppy Contributors
// SPDX-License-Identifier: MIT OR Apache-2.0
use crate::{Error, Triple};
use std::{borrow::Cow, collections::BTreeSet, ops::Deref};
// This is generated by the build script.
include!(concat!(env!("OUT_DIR"), "/current_platform.rs"));
/// A platform to evaluate target specifications against.
///
/// # Standard and custom platforms
///
/// `target-spec` recognizes two kinds of platforms:
///
/// * **Standard platforms:** These platforms are only specified by their triple string. For
/// example, the platform `x86_64-unknown-linux-gnu` is a standard platform since it is recognized
/// by Rust as a tier 1 platform.
///
/// All [builtin platforms](https://doc.rust-lang.org/nightly/rustc/platform-support.html) are
/// standard platforms.
///
/// By default, if a platform isn't builtin, target-spec attempts to heuristically determine the
/// characteristics of the platform based on the triple string. (Use the
/// [`new_strict`](Self::new_strict) constructor to disable this.)
///
/// * **Custom platforms:** These platforms are specified via both a triple string and a JSON file
/// in the format [defined by
/// Rust](https://docs.rust-embedded.org/embedonomicon/custom-target.html). Custom platforms are
/// used for targets not recognized by Rust.
#[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[must_use]
pub struct Platform {
triple: Triple,
target_features: TargetFeatures,
flags: BTreeSet<Cow<'static, str>>,
}
impl Platform {
/// Creates a new standard `Platform` from the given triple and target features.
///
/// Returns an error if this platform wasn't known to `target-spec`.
pub fn new(
triple_str: impl Into<Cow<'static, str>>,
target_features: TargetFeatures,
) -> Result<Self, Error> {
let triple = Triple::new(triple_str.into()).map_err(Error::UnknownPlatformTriple)?;
Ok(Self::from_triple(triple, target_features))
}
/// Creates a new standard `Platform` from the given triple and target features.
///
/// This constructor only consults the builtin platform table, and does not attempt to
/// heuristically determine the platform's characteristics based on the triple string.
pub fn new_strict(
triple_str: impl Into<Cow<'static, str>>,
target_features: TargetFeatures,
) -> Result<Self, Error> {
let triple = Triple::new_strict(triple_str.into()).map_err(Error::UnknownPlatformTriple)?;
Ok(Self::from_triple(triple, target_features))
}
/// Returns the current platform, as detected at build time.
///
/// This is currently always a standard platform, and will return an error if the current
/// platform was unknown to this version of `target-spec`.
///
/// # Notes
///
/// In the future, this constructor may also support custom platforms. This will not be
/// considered a breaking change.
pub fn current() -> Result<Self, Error> {
let triple = Triple::new(CURRENT_TARGET).map_err(Error::UnknownPlatformTriple)?;
let target_features = TargetFeatures::features(CURRENT_TARGET_FEATURES.iter().copied());
Ok(Self {
triple,
target_features,
flags: BTreeSet::new(),
})
}
/// Creates a new standard platform from a `Triple` and target features.
pub fn from_triple(triple: Triple, target_features: TargetFeatures) -> Self {
Self {
triple,
target_features,
flags: BTreeSet::new(),
}
}
/// Creates a new custom `Platform` from the given triple, platform, and target features.
#[cfg(feature = "custom")]
pub fn new_custom(
triple_str: impl Into<Cow<'static, str>>,
json: &str,
target_features: TargetFeatures,
) -> Result<Self, Error> {
let triple = Triple::new_custom(triple_str, json).map_err(Error::CustomPlatformCreate)?;
Ok(Self {
triple,
target_features,
flags: BTreeSet::new(),
})
}
/// Adds a set of flags to accept.
///
/// A flag is a single token like the `foo` in `cfg(not(foo))`.
///
/// A default `cargo build` will always evaluate flags to false, but custom wrappers may cause
/// some flags to evaluate to true. For example, as of version 0.6, `cargo web build` will cause
/// `cargo_web` to evaluate to true.
pub fn add_flags(&mut self, flags: impl IntoIterator<Item = impl Into<Cow<'static, str>>>) {
self.flags.extend(flags.into_iter().map(|s| s.into()));
}
/// Returns the target triple string for this platform.
pub fn triple_str(&self) -> &str {
self.triple.as_str()
}
/// Returns the set of flags enabled for this platform.
pub fn flags(&self) -> impl ExactSizeIterator<Item = &str> {
self.flags.iter().map(|flag| flag.deref())
}
/// Returns true if this flag was set with `add_flags`.
pub fn has_flag(&self, flag: impl AsRef<str>) -> bool {
self.flags.contains(flag.as_ref())
}
/// Returns true if this is a standard platform.
///
/// A standard platform can be either builtin, or heuristically determined.
///
/// # Examples
///
/// ```
/// use target_spec::{Platform, TargetFeatures};
///
/// // x86_64-unknown-linux-gnu is Linux x86_64.
/// let platform = Platform::new("x86_64-unknown-linux-gnu", TargetFeatures::Unknown).unwrap();
/// assert!(platform.is_standard());
/// ```
pub fn is_standard(&self) -> bool {
self.triple.is_standard()
}
/// Returns true if this is a builtin platform.
///
/// All builtin platforms are standard, but not all standard platforms are builtin.
///
/// # Examples
///
/// ```
/// use target_spec::{Platform, TargetFeatures};
///
/// // x86_64-unknown-linux-gnu is Linux x86_64, which is a Rust tier 1 platform.
/// let platform = Platform::new("x86_64-unknown-linux-gnu", TargetFeatures::Unknown).unwrap();
/// assert!(platform.is_builtin());
/// ```
pub fn is_builtin(&self) -> bool {
self.triple.is_builtin()
}
/// Returns true if this is a heuristically determined platform.
///
/// All heuristically determined platforms are standard, but most of the time, standard
/// platforms are builtin.
///
/// # Examples
///
/// ```
/// use target_spec::{Platform, TargetFeatures};
///
/// // armv5te-apple-darwin is not a real platform, but target-spec can heuristically
/// // guess at its characteristics.
/// let platform = Platform::new("armv5te-apple-darwin", TargetFeatures::Unknown).unwrap();
/// assert!(platform.is_heuristic());
/// ```
pub fn is_heuristic(&self) -> bool {
self.triple.is_heuristic()
}
/// Returns true if this is a custom platform.
///
/// This is always available, but if the `custom` feature isn't turned on this always returns
/// false.
pub fn is_custom(&self) -> bool {
self.triple.is_custom()
}
/// Returns the underlying [`Triple`].
pub fn triple(&self) -> &Triple {
&self.triple
}
/// Returns the set of target features for this platform.
pub fn target_features(&self) -> &TargetFeatures {
&self.target_features
}
#[cfg(feature = "summaries")]
pub(crate) fn custom_json(&self) -> Option<&str> {
self.triple.custom_json()
}
}
/// A set of target features to match.
#[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[non_exhaustive]
pub enum TargetFeatures {
/// The target features are unknown.
Unknown,
/// Only match the specified features.
Features(BTreeSet<Cow<'static, str>>),
/// Match all features.
All,
}
impl TargetFeatures {
/// Creates a new `TargetFeatures` which matches some features.
pub fn features(features: impl IntoIterator<Item = impl Into<Cow<'static, str>>>) -> Self {
TargetFeatures::Features(features.into_iter().map(|s| s.into()).collect())
}
/// Creates a new `TargetFeatures` which doesn't match any features.
pub fn none() -> Self {
TargetFeatures::Features(BTreeSet::new())
}
/// Returns `Some(true)` if this feature is a match, `Some(false)` if it isn't, and `None` if
/// the set of target features is unknown.
pub fn matches(&self, feature: &str) -> Option<bool> {
match self {
TargetFeatures::Unknown => None,
TargetFeatures::Features(features) => Some(features.contains(feature)),
TargetFeatures::All => Some(true),
}
}
}