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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";
// std::collections::Bound was stabilized in Rust 1.17
// but it was moved to core::ops later in Rust 1.26:
// https://doc.rust-lang.org/core/ops/enum.Bound.html
if minor >= 26 {
println!("cargo:rustc-cfg=ops_bound");
} else if minor >= 17 && cfg!(feature = "std") {
println!("cargo:rustc-cfg=collections_bound");
}
// CString::into_boxed_c_str stabilized in Rust 1.20:
// https://doc.rust-lang.org/std/ffi/struct.CString.html#method.into_boxed_c_str
if minor >= 20 {
println!("cargo:rustc-cfg=de_boxed_c_str");
}
// From<Box<T>> for Rc<T> / Arc<T> stabilized in Rust 1.21:
// https://doc.rust-lang.org/std/rc/struct.Rc.html#impl-From<Box<T>>
// https://doc.rust-lang.org/std/sync/struct.Arc.html#impl-From<Box<T>>
if minor >= 21 {
println!("cargo:rustc-cfg=de_rc_dst");
}
// Duration available in core since Rust 1.25:
// https://blog.rust-lang.org/2018/03/29/Rust-1.25.html#library-stabilizations
if minor >= 25 {
println!("cargo:rustc-cfg=core_duration");
}
// 128-bit integers stabilized in Rust 1.26:
// https://blog.rust-lang.org/2018/05/10/Rust-1.26.html
//
// Disabled on Emscripten targets as Emscripten doesn't
// currently support integers larger than 64 bits.
if minor >= 26 && !emscripten {
println!("cargo:rustc-cfg=integer128");
}
// Inclusive ranges methods stabilized in Rust 1.27:
// https://github.com/rust-lang/rust/pull/50758
if minor >= 27 {
println!("cargo:rustc-cfg=range_inclusive");
}
// Non-zero integers stabilized in Rust 1.28:
// https://github.com/rust-lang/rust/pull/50808
if minor >= 28 {
println!("cargo:rustc-cfg=num_nonzero");
}
}
fn rustc_minor_version() -> Option<u32> {
let rustc = match env::var_os("RUSTC") {
Some(rustc) => rustc,
None => return None,
};
let output = match Command::new(rustc).arg("--version").output() {
Ok(output) => output,
Err(_) => return None,
};
let version = match str::from_utf8(&output.stdout) {
Ok(version) => version,
Err(_) => return None,
};
let mut pieces = version.split('.');
if pieces.next() != Some("rustc 1") {
return None;
}
let next = match pieces.next() {
Some(next) => next,
None => return None,
};
u32::from_str(next).ok()
}