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use std::env;
use std::process::Command;
use std::str::{self, FromStr};
// The rustc-cfg strings below are *not* public API. Please let us know by
// opening a GitHub issue if your build environment requires some way to enable
// these cfgs other than by executing our build script.
fn main() {
let minor = match rustc_minor_version() {
Some(minor) => minor,
None => return,
};
let target = env::var("TARGET").unwrap();
let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
// 128-bit integers disabled on Emscripten targets as Emscripten doesn't
// currently support integers larger than 64 bits.
if !emscripten {
println!("cargo:rustc-cfg=integer128");
}
// MaybeUninit<T> stabilized in Rust 1.36:
// https://blog.rust-lang.org/2019/07/04/Rust-1.36.0.html
if minor >= 36 {
println!("cargo:rustc-cfg=maybe_uninit");
}
}
fn rustc_minor_version() -> Option<u32> {
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 next = pieces.next()?;
u32::from_str(next).ok()
}