Jason Macnak | efaa095 | 2019-12-12 22:33:33 +0000 | [diff] [blame] | 1 | use std::env; |
| 2 | use std::process::Command; |
| 3 | use std::str::{self, FromStr}; |
| 4 | |
| 5 | fn main(){ |
| 6 | let minor = match rustc_minor_version() { |
| 7 | Some(minor) => minor, |
| 8 | None => return, |
| 9 | }; |
| 10 | |
| 11 | // const fn stabilized in Rust 1.31: |
| 12 | if minor >= 31 { |
| 13 | println!("cargo:rustc-cfg=bitflags_const_fn"); |
| 14 | } |
| 15 | } |
| 16 | |
| 17 | fn rustc_minor_version() -> Option<u32> { |
| 18 | let rustc = match env::var_os("RUSTC") { |
| 19 | Some(rustc) => rustc, |
| 20 | None => return None, |
| 21 | }; |
| 22 | |
| 23 | let output = match Command::new(rustc).arg("--version").output() { |
| 24 | Ok(output) => output, |
| 25 | Err(_) => return None, |
| 26 | }; |
| 27 | |
| 28 | let version = match str::from_utf8(&output.stdout) { |
| 29 | Ok(version) => version, |
| 30 | Err(_) => return None, |
| 31 | }; |
| 32 | |
| 33 | let mut pieces = version.split('.'); |
| 34 | if pieces.next() != Some("rustc 1") { |
| 35 | return None; |
| 36 | } |
| 37 | |
| 38 | let next = match pieces.next() { |
| 39 | Some(next) => next, |
| 40 | None => return None, |
| 41 | }; |
| 42 | |
| 43 | u32::from_str(next).ok() |
| 44 | } |