Yi Kong | 9f04d26 | 2021-02-13 04:00:15 +0800 | [diff] [blame] | 1 | use std::env; |
| 2 | use std::process::Command; |
| 3 | use std::str; |
| 4 | |
| 5 | fn main() { |
| 6 | println!("cargo:rerun-if-changed=build.rs"); |
| 7 | |
| 8 | let minor = match rustc_minor_version() { |
| 9 | Some(n) => n, |
| 10 | None => return, |
| 11 | }; |
| 12 | |
| 13 | if minor >= 27 { |
| 14 | println!("cargo:rustc-cfg=crc32fast_stdarchx86"); |
| 15 | } |
| 16 | } |
| 17 | |
| 18 | fn rustc_minor_version() -> Option<u32> { |
| 19 | macro_rules! otry { |
| 20 | ($e:expr) => { |
| 21 | match $e { |
| 22 | Some(e) => e, |
| 23 | None => return None, |
| 24 | } |
| 25 | }; |
| 26 | } |
| 27 | let rustc = otry!(env::var_os("RUSTC")); |
| 28 | let output = otry!(Command::new(rustc).arg("--version").output().ok()); |
| 29 | let version = otry!(str::from_utf8(&output.stdout).ok()); |
| 30 | let mut pieces = version.split('.'); |
| 31 | if pieces.next() != Some("rustc 1") { |
| 32 | return None; |
| 33 | } |
| 34 | otry!(pieces.next()).parse().ok() |
| 35 | } |