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|
// SPDX-License-Identifier: Apache-2.0 OR MIT
// The rustc-cfg emitted by the build script are *not* public API.
use std::{env, fs, iter, path::PathBuf, process::Command, str};
fn main() {
println!("cargo:rerun-if-changed=build.rs");
let version = match rustc_version() {
Ok(version) => version.print(),
Err(e) => {
if env::var_os("CONST_FN_DENY_WARNINGS").unwrap_or_default() == "1" {
panic!("unable to determine rustc version")
}
println!(
"cargo:warning={}: unable to determine rustc version: {}",
env!("CARGO_PKG_NAME"),
e
);
return;
}
};
let out_dir: PathBuf = env::var_os("OUT_DIR").expect("OUT_DIR not set").into();
let out_file = &out_dir.join("version");
fs::write(out_file, version)
.unwrap_or_else(|e| panic!("failed to write {}: {}", out_file.display(), e));
if assume_incomplete_release() {
println!("cargo:rustc-cfg=const_fn_assume_incomplete_release");
}
// Mark as build script has been run successfully.
println!("cargo:rustc-cfg=const_fn_has_build_script");
}
fn rustc_version() -> Result<Version, String> {
let rustc = env::var_os("RUSTC").ok_or("RUSTC not set")?;
let rustc_wrapper = if env::var_os("CARGO_ENCODED_RUSTFLAGS").is_some() {
env::var_os("RUSTC_WRAPPER").filter(|v| !v.is_empty())
} else {
// Cargo sets environment variables for wrappers correctly only since https://github.com/rust-lang/cargo/pull/9601.
None
};
// Do not apply RUSTC_WORKSPACE_WRAPPER: https://github.com/cuviper/autocfg/issues/58#issuecomment-2067625980
let mut rustc = rustc_wrapper.into_iter().chain(iter::once(rustc));
let mut cmd = Command::new(rustc.next().unwrap());
cmd.args(rustc);
// Use verbose version output because the packagers add extra strings to the normal version output.
// Do not use long flags (--version --verbose) because clippy-deriver doesn't handle them properly.
// -vV is also matched with that cargo internally uses: https://github.com/rust-lang/cargo/blob/14b46ecc62aa671d7477beba237ad9c6a209cf5d/src/cargo/util/rustc.rs#L65
let output =
cmd.arg("-vV").output().map_err(|e| format!("could not execute {:?}: {}", cmd, e))?;
let verbose_version = str::from_utf8(&output.stdout)
.map_err(|e| format!("failed to parse output of {:?}: {}", cmd, e))?;
Version::parse(verbose_version)
.ok_or_else(|| format!("unexpected output from {:?}: {}", cmd, verbose_version))
}
struct Version {
minor: u32,
nightly: bool,
}
impl Version {
fn parse(verbose_version: &str) -> Option<Self> {
let mut release = verbose_version
.lines()
.find(|line| line.starts_with("release: "))
.map(|line| &line["release: ".len()..])?
.splitn(2, '-');
let version = release.next().unwrap();
let channel = release.next().unwrap_or_default();
let mut digits = version.splitn(3, '.');
let major = digits.next()?;
if major != "1" {
return None;
}
let minor = digits.next()?.parse::<u32>().ok()?;
let _patch = digits.next().unwrap_or("0").parse::<u32>().ok()?;
let nightly = channel == "nightly" || channel == "dev";
Some(Self { minor, nightly })
}
fn print(&self) -> String {
format!("Version {{ minor: {}, nightly: {} }}\n", self.minor, self.nightly)
}
}
// https://github.com/taiki-e/const_fn/issues/27
// https://github.com/rust-lang/rust/pull/81468
fn assume_incomplete_release() -> bool {
// Recognized formats: -Z( )?assume-incomplete-release
// https://github.com/rust-lang/cargo/issues/10111
if let Some(rustflags) = env::var_os("CARGO_ENCODED_RUSTFLAGS") {
for mut flag in rustflags.to_string_lossy().split('\x1f') {
if flag.starts_with("-Z") {
flag = &flag["-Z".len()..];
}
if flag == "assume-incomplete-release" {
return true;
}
}
}
false
}
|
