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use std::env;
use std::process::Command;
use std::str::{self, FromStr};
fn main() {
println!("cargo:rerun-if-changed=build.rs");
// Decide ideal limb width for arithmetic in the float parser. Refer to
// src/lexical/math.rs for where this has an effect.
let target_arch = env::var("CARGO_CFG_TARGET_ARCH").unwrap();
match target_arch.as_str() {
"aarch64" | "mips64" | "powerpc64" | "x86_64" => {
println!("cargo:rustc-cfg=limb_width_64");
}
_ => {
println!("cargo:rustc-cfg=limb_width_32");
}
}
let minor = match rustc_minor_version() {
Some(minor) => minor,
None => return,
};
// BTreeMap::get_key_value
if minor < 40 {
println!("cargo:rustc-cfg=no_btreemap_get_key_value");
}
// BTreeMap::remove_entry
if minor < 45 {
println!("cargo:rustc-cfg=no_btreemap_remove_entry");
}
// BTreeMap::retain
if minor < 53 {
println!("cargo:rustc-cfg=no_btreemap_retain");
}
}
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()
}