| 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(backtrace)] |
| #![allow(dead_code)] |
| |
| use std::backtrace::{Backtrace, BacktraceStatus}; |
| use std::error::Error; |
| use std::fmt::{self, Display}; |
| |
| #[derive(Debug)] |
| struct E; |
| |
| impl Display for E { |
| fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result { |
| unimplemented!() |
| } |
| } |
| |
| impl Error for E { |
| fn backtrace(&self) -> Option<&Backtrace> { |
| let backtrace = Backtrace::capture(); |
| match backtrace.status() { |
| BacktraceStatus::Captured | BacktraceStatus::Disabled | _ => {} |
| } |
| unimplemented!() |
| } |
| } |
| "#; |
| |
| 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 < 38 { |
| println!("cargo:rustc-cfg=anyhow_no_macro_reexport"); |
| } |
| |
| if rustc < 51 { |
| println!("cargo:rustc-cfg=anyhow_no_ptr_addr_of"); |
| } |
| } |
| |
| 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()?; |
| Command::new(rustc) |
| .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) |
| .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() |
| } |