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#![allow(clippy::option_if_let_else)]
use std::env;
use std::fs;
use std::path::Path;
use std::process::{Command, ExitStatus, Stdio};
use std::str;
#[cfg(all(feature = "backtrace", not(feature = "std")))]
compile_error! {
"`backtrace` feature without `std` feature is not supported"
}
// This code exercises the surface area that we expect of the std Backtrace
// type. If the current toolchain is able to compile it, we go ahead and use
// backtrace in anyhow.
const PROBE: &str = r#"
#![feature(error_generic_member_access, provide_any)]
use std::any::{Demand, Provider};
use std::backtrace::{Backtrace, BacktraceStatus};
use std::error::Error;
use std::fmt::{self, Display};
#[derive(Debug)]
struct E {
backtrace: Backtrace,
}
impl Display for E {
fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result {
unimplemented!()
}
}
impl Error for E {
fn provide<'a>(&'a self, demand: &mut Demand<'a>) {
demand.provide_ref(&self.backtrace);
}
}
struct P;
impl Provider for P {
fn provide<'a>(&'a self, _demand: &mut Demand<'a>) {}
}
const _: fn() = || {
let backtrace: Backtrace = Backtrace::capture();
let status: BacktraceStatus = backtrace.status();
match status {
BacktraceStatus::Captured | BacktraceStatus::Disabled | _ => {}
}
};
const _: fn(&dyn Error) -> Option<&Backtrace> = |err| err.request_ref::<Backtrace>();
"#;
fn main() {
if cfg!(feature = "std") {
match compile_probe() {
Some(status) if status.success() => println!("cargo:rustc-cfg=backtrace"),
_ => {}
}
}
let rustc = match rustc_minor_version() {
Some(rustc) => rustc,
None => return,
};
if rustc < 51 {
println!("cargo:rustc-cfg=anyhow_no_ptr_addr_of");
}
if rustc < 52 {
println!("cargo:rustc-cfg=anyhow_no_fmt_arguments_as_str");
}
}
fn compile_probe() -> Option<ExitStatus> {
let rustc = env::var_os("RUSTC")?;
let out_dir = env::var_os("OUT_DIR")?;
let probefile = Path::new(&out_dir).join("probe.rs");
fs::write(&probefile, PROBE).ok()?;
// Make sure to pick up Cargo rustc configuration.
let mut cmd = if let Some(wrapper) = env::var_os("RUSTC_WRAPPER") {
let mut cmd = Command::new(wrapper);
// The wrapper's first argument is supposed to be the path to rustc.
cmd.arg(rustc);
cmd
} else {
Command::new(rustc)
};
cmd.stderr(Stdio::null())
.arg("--edition=2018")
.arg("--crate-name=anyhow_build")
.arg("--crate-type=lib")
.arg("--emit=metadata")
.arg("--out-dir")
.arg(out_dir)
.arg(probefile);
if let Some(target) = env::var_os("TARGET") {
cmd.arg("--target").arg(target);
}
// If Cargo wants to set RUSTFLAGS, use that.
if let Ok(rustflags) = env::var("CARGO_ENCODED_RUSTFLAGS") {
if !rustflags.is_empty() {
for arg in rustflags.split('\x1f') {
cmd.arg(arg);
}
}
}
cmd.status().ok()
}
fn rustc_minor_version() -> Option<u32> {
let rustc = env::var_os("RUSTC")?;
let output = Command::new(rustc).arg("--version").output().ok()?;
let version = str::from_utf8(&output.stdout).ok()?;
let mut pieces = version.split('.');
if pieces.next() != Some("rustc 1") {
return None;
}
pieces.next()?.parse().ok()
}