| use std::env; |
| use std::process::{self, Command}; |
| use std::str; |
| |
| fn main() { |
| println!("cargo:rerun-if-changed=build.rs"); |
| |
| let version = match rustc_version() { |
| Some(version) => version, |
| None => return, |
| }; |
| |
| if version.minor < 31 { |
| eprintln!("Minimum supported rustc version is 1.31"); |
| process::exit(1); |
| } |
| |
| if version.minor < 53 { |
| // https://github.com/rust-lang/rust/issues/43081 |
| println!("cargo:rustc-cfg=needs_invalid_span_workaround"); |
| } |
| } |
| |
| struct RustcVersion { |
| minor: u32, |
| } |
| |
| fn rustc_version() -> Option<RustcVersion> { |
| 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; |
| } |
| let minor = pieces.next()?.parse().ok()?; |
| Some(RustcVersion { minor }) |
| } |