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use std::env;
use std::process::Command;
use std::str;
fn main() {
println!("cargo:rerun-if-changed=build.rs");
let minor = match rustc_minor_version() {
Some(n) => n,
None => return,
};
if minor >= 27 {
println!("cargo:rustc-cfg=crc32fast_stdarchx86");
}
}
fn rustc_minor_version() -> Option<u32> {
macro_rules! otry {
($e:expr) => {
match $e {
Some(e) => e,
None => return None,
}
};
}
let rustc = otry!(env::var_os("RUSTC"));
let output = otry!(Command::new(rustc).arg("--version").output().ok());
let version = otry!(str::from_utf8(&output.stdout).ok());
let mut pieces = version.split('.');
if pieces.next() != Some("rustc 1") {
return None;
}
otry!(pieces.next()).parse().ok()
}