120 lines
3.9 KiB
Rust
120 lines
3.9 KiB
Rust
use std::env;
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use std::ffi::OsString;
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use std::path::Path;
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use std::process::{self, Command, Stdio};
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fn main() {
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println!("cargo:rerun-if-changed=build/probe.rs");
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let error_generic_member_access;
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let consider_rustc_bootstrap;
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if compile_probe(false) {
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// This is a nightly or dev compiler, so it supports unstable features
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// regardless of RUSTC_BOOTSTRAP. No need to rerun build script if
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// RUSTC_BOOTSTRAP is changed.
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error_generic_member_access = true;
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consider_rustc_bootstrap = false;
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} else if let Some(rustc_bootstrap) = env::var_os("RUSTC_BOOTSTRAP") {
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if compile_probe(true) {
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// This is a stable or beta compiler for which the user has set
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// RUSTC_BOOTSTRAP to turn on unstable features. Rerun build script
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// if they change it.
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error_generic_member_access = true;
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consider_rustc_bootstrap = true;
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} else if rustc_bootstrap == "1" {
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// This compiler does not support the generic member access API in
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// the form that thiserror expects. No need to pay attention to
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// RUSTC_BOOTSTRAP.
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error_generic_member_access = false;
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consider_rustc_bootstrap = false;
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} else {
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// This is a stable or beta compiler for which RUSTC_BOOTSTRAP is
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// set to restrict the use of unstable features by this crate.
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error_generic_member_access = false;
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consider_rustc_bootstrap = true;
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}
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} else {
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// Without RUSTC_BOOTSTRAP, this compiler does not support the generic
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// member access API in the form that thiserror expects, but try again
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// if the user turns on unstable features.
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error_generic_member_access = false;
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consider_rustc_bootstrap = true;
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}
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if error_generic_member_access {
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println!("cargo:rustc-cfg=error_generic_member_access");
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}
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if consider_rustc_bootstrap {
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println!("cargo:rerun-if-env-changed=RUSTC_BOOTSTRAP");
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}
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}
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fn compile_probe(rustc_bootstrap: bool) -> bool {
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if env::var_os("RUSTC_STAGE").is_some() {
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// We are running inside rustc bootstrap. This is a highly non-standard
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// environment with issues such as:
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//
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// https://github.com/rust-lang/cargo/issues/11138
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// https://github.com/rust-lang/rust/issues/114839
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//
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// Let's just not use nightly features here.
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return false;
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}
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let rustc = cargo_env_var("RUSTC");
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let out_dir = cargo_env_var("OUT_DIR");
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let probefile = Path::new("build").join("probe.rs");
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// Make sure to pick up Cargo rustc configuration.
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let mut cmd = if let Some(wrapper) = env::var_os("RUSTC_WRAPPER") {
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let mut cmd = Command::new(wrapper);
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// The wrapper's first argument is supposed to be the path to rustc.
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cmd.arg(rustc);
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cmd
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} else {
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Command::new(rustc)
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};
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if !rustc_bootstrap {
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cmd.env_remove("RUSTC_BOOTSTRAP");
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}
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cmd.stderr(Stdio::null())
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.arg("--edition=2018")
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.arg("--crate-name=thiserror")
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.arg("--crate-type=lib")
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.arg("--emit=dep-info,metadata")
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.arg("--out-dir")
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.arg(out_dir)
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.arg(probefile);
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if let Some(target) = env::var_os("TARGET") {
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cmd.arg("--target").arg(target);
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}
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// If Cargo wants to set RUSTFLAGS, use that.
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if let Ok(rustflags) = env::var("CARGO_ENCODED_RUSTFLAGS") {
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if !rustflags.is_empty() {
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for arg in rustflags.split('\x1f') {
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cmd.arg(arg);
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}
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}
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}
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match cmd.status() {
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Ok(status) => status.success(),
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Err(_) => false,
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}
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}
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fn cargo_env_var(key: &str) -> OsString {
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env::var_os(key).unwrap_or_else(|| {
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eprintln!(
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"Environment variable ${} is not set during execution of build script",
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key,
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);
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process::exit(1);
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})
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}
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