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93 lines
2.4 KiB
93 lines
2.4 KiB
use std::env;
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use std::fs;
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use std::path::Path;
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use std::process::{Command, ExitStatus, Stdio};
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use std::str;
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#[cfg(all(feature = "backtrace", not(feature = "std")))]
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compile_error! {
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"`backtrace` feature without `std` feature is not supported"
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}
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// This code exercises the surface area that we expect of the std Backtrace
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// type. If the current toolchain is able to compile it, we go ahead and use
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// backtrace in anyhow.
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const PROBE: &str = r#"
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#![feature(backtrace)]
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#![allow(dead_code)]
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use std::backtrace::{Backtrace, BacktraceStatus};
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use std::error::Error;
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use std::fmt::{self, Display};
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#[derive(Debug)]
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struct E;
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impl Display for E {
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fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result {
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unimplemented!()
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}
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}
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impl Error for E {
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fn backtrace(&self) -> Option<&Backtrace> {
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let backtrace = Backtrace::capture();
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match backtrace.status() {
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BacktraceStatus::Captured | BacktraceStatus::Disabled | _ => {}
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}
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unimplemented!()
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}
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}
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"#;
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fn main() {
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if cfg!(feature = "std") {
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match compile_probe() {
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Some(status) if status.success() => println!("cargo:rustc-cfg=backtrace"),
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_ => {}
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}
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}
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let rustc = match rustc_minor_version() {
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Some(rustc) => rustc,
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None => return,
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};
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if rustc < 38 {
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println!("cargo:rustc-cfg=anyhow_no_macro_reexport");
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}
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if rustc < 51 {
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println!("cargo:rustc-cfg=anyhow_no_ptr_addr_of");
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}
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}
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fn compile_probe() -> Option<ExitStatus> {
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let rustc = env::var_os("RUSTC")?;
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let out_dir = env::var_os("OUT_DIR")?;
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let probefile = Path::new(&out_dir).join("probe.rs");
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fs::write(&probefile, PROBE).ok()?;
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Command::new(rustc)
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.stderr(Stdio::null())
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.arg("--edition=2018")
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.arg("--crate-name=anyhow_build")
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.arg("--crate-type=lib")
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.arg("--emit=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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.status()
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.ok()
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}
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fn rustc_minor_version() -> Option<u32> {
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let rustc = env::var_os("RUSTC")?;
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let output = Command::new(rustc).arg("--version").output().ok()?;
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let version = str::from_utf8(&output.stdout).ok()?;
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let mut pieces = version.split('.');
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if pieces.next() != Some("rustc 1") {
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return None;
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}
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pieces.next()?.parse().ok()
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}
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