blob: cd6df2379e6f3bc1ac9b346a91bd899eab496de5 [file] [log] [blame]
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 minor = match rustc_minor_version() {
Some(n) => n,
None => return,
};
if minor >= 26 {
println!("cargo:rustc-cfg=u128");
}
if !enable_use_proc_macro(&target) {
return;
}
println!("cargo:rustc-cfg=use_proc_macro");
// Rust 1.29 stabilized the necessary APIs in the `proc_macro` crate
if (minor >= 29 && !cfg!(procmacro2_semver_exempt)) || cfg!(feature = "nightly") {
println!("cargo:rustc-cfg=wrap_proc_macro");
if cfg!(procmacro2_semver_exempt) {
println!("cargo:rustc-cfg=super_unstable");
// https://github.com/alexcrichton/proc-macro2/issues/147
println!("cargo:rustc-cfg=procmacro2_semver_exempt");
}
}
if minor == 29 {
println!("cargo:rustc-cfg=slow_extend");
}
}
fn enable_use_proc_macro(target: &str) -> bool {
// wasm targets don't have the `proc_macro` crate, disable this feature.
if target.contains("wasm32") {
return false;
}
// Otherwise, only enable it if our feature is actually enabled.
cfg!(feature = "proc-macro")
}
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()
}