use std::env;
use std::process::Command;
use std::str;
fn main() {
println!("cargo:rerun-if-changed=build.rs");
let target = env::var("TARGET").unwrap();
let version = match rustc_version() {
Some(version) => version,
None => return,
};
if version.minor >= 26 {
println!("cargo:rustc-cfg=u128");
}
if !enable_use_proc_macro(&target) {
return;
}
println!("cargo:rustc-cfg=use_proc_macro");
let semver_exempt = cfg!(procmacro2_semver_exempt);
if semver_exempt {
println!("cargo:rustc-cfg=procmacro2_semver_exempt");
}
if version.nightly || version.minor >= 29 && !semver_exempt {
println!("cargo:rustc-cfg=wrap_proc_macro");
}
if version.minor == 29 {
println!("cargo:rustc-cfg=slow_extend");
}
if version.nightly {
println!("cargo:rustc-cfg=nightly");
}
if semver_exempt && version.nightly {
println!("cargo:rustc-cfg=super_unstable");
}
}
fn enable_use_proc_macro(target: &str) -> bool {
if target.contains("wasm32") {
return false;
}
cfg!(feature = "proc-macro")
}
struct RustcVersion {
minor: u32,
nightly: bool,
}
fn rustc_version() -> Option<RustcVersion> {
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 nightly = version.contains("nightly");
let mut pieces = version.split('.');
if pieces.next() != Some("rustc 1") {
return None;
}
let minor = otry!(pieces.next());
let minor = otry!(minor.parse().ok());
Some(RustcVersion {
minor: minor,
nightly: nightly,
})
}