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use std::env;
use std::process::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 < 54 {
println!("cargo:rustc-cfg=no_literal_fromstr");
}
}
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 })
}