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Diffstat (limited to 'vendor/autocfg/src/lib.rs')
| -rw-r--r-- | vendor/autocfg/src/lib.rs | 453 |
1 files changed, 453 insertions, 0 deletions
diff --git a/vendor/autocfg/src/lib.rs b/vendor/autocfg/src/lib.rs new file mode 100644 index 000000000..cbe393a9b --- /dev/null +++ b/vendor/autocfg/src/lib.rs @@ -0,0 +1,453 @@ +//! A Rust library for build scripts to automatically configure code based on +//! compiler support. Code snippets are dynamically tested to see if the `rustc` +//! will accept them, rather than hard-coding specific version support. +//! +//! +//! ## Usage +//! +//! Add this to your `Cargo.toml`: +//! +//! ```toml +//! [build-dependencies] +//! autocfg = "1" +//! ``` +//! +//! Then use it in your `build.rs` script to detect compiler features. For +//! example, to test for 128-bit integer support, it might look like: +//! +//! ```rust +//! extern crate autocfg; +//! +//! fn main() { +//! # // Normally, cargo will set `OUT_DIR` for build scripts. +//! # std::env::set_var("OUT_DIR", "target"); +//! let ac = autocfg::new(); +//! ac.emit_has_type("i128"); +//! +//! // (optional) We don't need to rerun for anything external. +//! autocfg::rerun_path("build.rs"); +//! } +//! ``` +//! +//! If the type test succeeds, this will write a `cargo:rustc-cfg=has_i128` line +//! for Cargo, which translates to Rust arguments `--cfg has_i128`. Then in the +//! rest of your Rust code, you can add `#[cfg(has_i128)]` conditions on code that +//! should only be used when the compiler supports it. +//! +//! ## Caution +//! +//! Many of the probing methods of `AutoCfg` document the particular template they +//! use, **subject to change**. The inputs are not validated to make sure they are +//! semantically correct for their expected use, so it's _possible_ to escape and +//! inject something unintended. However, such abuse is unsupported and will not +//! be considered when making changes to the templates. + +#![deny(missing_debug_implementations)] +#![deny(missing_docs)] +// allow future warnings that can't be fixed while keeping 1.0 compatibility +#![allow(unknown_lints)] +#![allow(bare_trait_objects)] +#![allow(ellipsis_inclusive_range_patterns)] + +/// Local macro to avoid `std::try!`, deprecated in Rust 1.39. +macro_rules! try { + ($result:expr) => { + match $result { + Ok(value) => value, + Err(error) => return Err(error), + } + }; +} + +use std::env; +use std::ffi::OsString; +use std::fs; +use std::io::{stderr, Write}; +use std::path::{Path, PathBuf}; +use std::process::{Command, Stdio}; +#[allow(deprecated)] +use std::sync::atomic::ATOMIC_USIZE_INIT; +use std::sync::atomic::{AtomicUsize, Ordering}; + +mod error; +pub use error::Error; + +mod version; +use version::Version; + +#[cfg(test)] +mod tests; + +/// Helper to detect compiler features for `cfg` output in build scripts. +#[derive(Clone, Debug)] +pub struct AutoCfg { + out_dir: PathBuf, + rustc: PathBuf, + rustc_version: Version, + target: Option<OsString>, + no_std: bool, + rustflags: Vec<String>, +} + +/// Writes a config flag for rustc on standard out. +/// +/// This looks like: `cargo:rustc-cfg=CFG` +/// +/// Cargo will use this in arguments to rustc, like `--cfg CFG`. +pub fn emit(cfg: &str) { + println!("cargo:rustc-cfg={}", cfg); +} + +/// Writes a line telling Cargo to rerun the build script if `path` changes. +/// +/// This looks like: `cargo:rerun-if-changed=PATH` +/// +/// This requires at least cargo 0.7.0, corresponding to rustc 1.6.0. Earlier +/// versions of cargo will simply ignore the directive. +pub fn rerun_path(path: &str) { + println!("cargo:rerun-if-changed={}", path); +} + +/// Writes a line telling Cargo to rerun the build script if the environment +/// variable `var` changes. +/// +/// This looks like: `cargo:rerun-if-env-changed=VAR` +/// +/// This requires at least cargo 0.21.0, corresponding to rustc 1.20.0. Earlier +/// versions of cargo will simply ignore the directive. +pub fn rerun_env(var: &str) { + println!("cargo:rerun-if-env-changed={}", var); +} + +/// Create a new `AutoCfg` instance. +/// +/// # Panics +/// +/// Panics if `AutoCfg::new()` returns an error. +pub fn new() -> AutoCfg { + AutoCfg::new().unwrap() +} + +impl AutoCfg { + /// Create a new `AutoCfg` instance. + /// + /// # Common errors + /// + /// - `rustc` can't be executed, from `RUSTC` or in the `PATH`. + /// - The version output from `rustc` can't be parsed. + /// - `OUT_DIR` is not set in the environment, or is not a writable directory. + /// + pub fn new() -> Result<Self, Error> { + match env::var_os("OUT_DIR") { + Some(d) => Self::with_dir(d), + None => Err(error::from_str("no OUT_DIR specified!")), + } + } + + /// Create a new `AutoCfg` instance with the specified output directory. + /// + /// # Common errors + /// + /// - `rustc` can't be executed, from `RUSTC` or in the `PATH`. + /// - The version output from `rustc` can't be parsed. + /// - `dir` is not a writable directory. + /// + pub fn with_dir<T: Into<PathBuf>>(dir: T) -> Result<Self, Error> { + let rustc = env::var_os("RUSTC").unwrap_or_else(|| "rustc".into()); + let rustc: PathBuf = rustc.into(); + let rustc_version = try!(Version::from_rustc(&rustc)); + + let target = env::var_os("TARGET"); + + // Sanity check the output directory + let dir = dir.into(); + let meta = try!(fs::metadata(&dir).map_err(error::from_io)); + if !meta.is_dir() || meta.permissions().readonly() { + return Err(error::from_str("output path is not a writable directory")); + } + + let mut ac = AutoCfg { + rustflags: rustflags(&target, &dir), + out_dir: dir, + rustc: rustc, + rustc_version: rustc_version, + target: target, + no_std: false, + }; + + // Sanity check with and without `std`. + if !ac.probe("").unwrap_or(false) { + ac.no_std = true; + if !ac.probe("").unwrap_or(false) { + // Neither worked, so assume nothing... + ac.no_std = false; + let warning = b"warning: autocfg could not probe for `std`\n"; + stderr().write_all(warning).ok(); + } + } + Ok(ac) + } + + /// Test whether the current `rustc` reports a version greater than + /// or equal to "`major`.`minor`". + pub fn probe_rustc_version(&self, major: usize, minor: usize) -> bool { + self.rustc_version >= Version::new(major, minor, 0) + } + + /// Sets a `cfg` value of the form `rustc_major_minor`, like `rustc_1_29`, + /// if the current `rustc` is at least that version. + pub fn emit_rustc_version(&self, major: usize, minor: usize) { + if self.probe_rustc_version(major, minor) { + emit(&format!("rustc_{}_{}", major, minor)); + } + } + + fn probe<T: AsRef<[u8]>>(&self, code: T) -> Result<bool, Error> { + #[allow(deprecated)] + static ID: AtomicUsize = ATOMIC_USIZE_INIT; + + let id = ID.fetch_add(1, Ordering::Relaxed); + let mut command = Command::new(&self.rustc); + command + .arg("--crate-name") + .arg(format!("probe{}", id)) + .arg("--crate-type=lib") + .arg("--out-dir") + .arg(&self.out_dir) + .arg("--emit=llvm-ir"); + + if let Some(target) = self.target.as_ref() { + command.arg("--target").arg(target); + } + + command.args(&self.rustflags); + + command.arg("-").stdin(Stdio::piped()); + let mut child = try!(command.spawn().map_err(error::from_io)); + let mut stdin = child.stdin.take().expect("rustc stdin"); + + if self.no_std { + try!(stdin.write_all(b"#![no_std]\n").map_err(error::from_io)); + } + try!(stdin.write_all(code.as_ref()).map_err(error::from_io)); + drop(stdin); + + let status = try!(child.wait().map_err(error::from_io)); + Ok(status.success()) + } + + /// Tests whether the given sysroot crate can be used. + /// + /// The test code is subject to change, but currently looks like: + /// + /// ```ignore + /// extern crate CRATE as probe; + /// ``` + pub fn probe_sysroot_crate(&self, name: &str) -> bool { + self.probe(format!("extern crate {} as probe;", name)) // `as _` wasn't stabilized until Rust 1.33 + .unwrap_or(false) + } + + /// Emits a config value `has_CRATE` if `probe_sysroot_crate` returns true. + pub fn emit_sysroot_crate(&self, name: &str) { + if self.probe_sysroot_crate(name) { + emit(&format!("has_{}", mangle(name))); + } + } + + /// Tests whether the given path can be used. + /// + /// The test code is subject to change, but currently looks like: + /// + /// ```ignore + /// pub use PATH; + /// ``` + pub fn probe_path(&self, path: &str) -> bool { + self.probe(format!("pub use {};", path)).unwrap_or(false) + } + + /// Emits a config value `has_PATH` if `probe_path` returns true. + /// + /// Any non-identifier characters in the `path` will be replaced with + /// `_` in the generated config value. + pub fn emit_has_path(&self, path: &str) { + if self.probe_path(path) { + emit(&format!("has_{}", mangle(path))); + } + } + + /// Emits the given `cfg` value if `probe_path` returns true. + pub fn emit_path_cfg(&self, path: &str, cfg: &str) { + if self.probe_path(path) { + emit(cfg); + } + } + + /// Tests whether the given trait can be used. + /// + /// The test code is subject to change, but currently looks like: + /// + /// ```ignore + /// pub trait Probe: TRAIT + Sized {} + /// ``` + pub fn probe_trait(&self, name: &str) -> bool { + self.probe(format!("pub trait Probe: {} + Sized {{}}", name)) + .unwrap_or(false) + } + + /// Emits a config value `has_TRAIT` if `probe_trait` returns true. + /// + /// Any non-identifier characters in the trait `name` will be replaced with + /// `_` in the generated config value. + pub fn emit_has_trait(&self, name: &str) { + if self.probe_trait(name) { + emit(&format!("has_{}", mangle(name))); + } + } + + /// Emits the given `cfg` value if `probe_trait` returns true. + pub fn emit_trait_cfg(&self, name: &str, cfg: &str) { + if self.probe_trait(name) { + emit(cfg); + } + } + + /// Tests whether the given type can be used. + /// + /// The test code is subject to change, but currently looks like: + /// + /// ```ignore + /// pub type Probe = TYPE; + /// ``` + pub fn probe_type(&self, name: &str) -> bool { + self.probe(format!("pub type Probe = {};", name)) + .unwrap_or(false) + } + + /// Emits a config value `has_TYPE` if `probe_type` returns true. + /// + /// Any non-identifier characters in the type `name` will be replaced with + /// `_` in the generated config value. + pub fn emit_has_type(&self, name: &str) { + if self.probe_type(name) { + emit(&format!("has_{}", mangle(name))); + } + } + + /// Emits the given `cfg` value if `probe_type` returns true. + pub fn emit_type_cfg(&self, name: &str, cfg: &str) { + if self.probe_type(name) { + emit(cfg); + } + } + + /// Tests whether the given expression can be used. + /// + /// The test code is subject to change, but currently looks like: + /// + /// ```ignore + /// pub fn probe() { let _ = EXPR; } + /// ``` + pub fn probe_expression(&self, expr: &str) -> bool { + self.probe(format!("pub fn probe() {{ let _ = {}; }}", expr)) + .unwrap_or(false) + } + + /// Emits the given `cfg` value if `probe_expression` returns true. + pub fn emit_expression_cfg(&self, expr: &str, cfg: &str) { + if self.probe_expression(expr) { + emit(cfg); + } + } + + /// Tests whether the given constant expression can be used. + /// + /// The test code is subject to change, but currently looks like: + /// + /// ```ignore + /// pub const PROBE: () = ((), EXPR).0; + /// ``` + pub fn probe_constant(&self, expr: &str) -> bool { + self.probe(format!("pub const PROBE: () = ((), {}).0;", expr)) + .unwrap_or(false) + } + + /// Emits the given `cfg` value if `probe_constant` returns true. + pub fn emit_constant_cfg(&self, expr: &str, cfg: &str) { + if self.probe_constant(expr) { + emit(cfg); + } + } +} + +fn mangle(s: &str) -> String { + s.chars() + .map(|c| match c { + 'A'...'Z' | 'a'...'z' | '0'...'9' => c, + _ => '_', + }) + .collect() +} + +fn dir_contains_target( + target: &Option<OsString>, + dir: &Path, + cargo_target_dir: Option<OsString>, +) -> bool { + target + .as_ref() + .and_then(|target| { + dir.to_str().and_then(|dir| { + let mut cargo_target_dir = cargo_target_dir + .map(PathBuf::from) + .unwrap_or_else(|| PathBuf::from("target")); + cargo_target_dir.push(target); + + cargo_target_dir + .to_str() + .map(|cargo_target_dir| dir.contains(&cargo_target_dir)) + }) + }) + .unwrap_or(false) +} + +fn rustflags(target: &Option<OsString>, dir: &Path) -> Vec<String> { + // Starting with rust-lang/cargo#9601, shipped in Rust 1.55, Cargo always sets + // CARGO_ENCODED_RUSTFLAGS for any host/target build script invocation. This + // includes any source of flags, whether from the environment, toml config, or + // whatever may come in the future. The value is either an empty string, or a + // list of arguments separated by the ASCII unit separator (US), 0x1f. + if let Ok(a) = env::var("CARGO_ENCODED_RUSTFLAGS") { + return if a.is_empty() { + Vec::new() + } else { + a.split('\x1f').map(str::to_string).collect() + }; + } + + // Otherwise, we have to take a more heuristic approach, and we don't + // support values from toml config at all. + // + // Cargo only applies RUSTFLAGS for building TARGET artifact in + // cross-compilation environment. Sadly, we don't have a way to detect + // when we're building HOST artifact in a cross-compilation environment, + // so for now we only apply RUSTFLAGS when cross-compiling an artifact. + // + // See https://github.com/cuviper/autocfg/pull/10#issuecomment-527575030. + if *target != env::var_os("HOST") + || dir_contains_target(target, dir, env::var_os("CARGO_TARGET_DIR")) + { + if let Ok(rustflags) = env::var("RUSTFLAGS") { + // This is meant to match how cargo handles the RUSTFLAGS environment variable. + // See https://github.com/rust-lang/cargo/blob/69aea5b6f69add7c51cca939a79644080c0b0ba0/src/cargo/core/compiler/build_context/target_info.rs#L434-L441 + return rustflags + .split(' ') + .map(str::trim) + .filter(|s| !s.is_empty()) + .map(str::to_string) + .collect(); + } + } + + Vec::new() +} |