use std::env; use std::process::Command; use std::str::{self, FromStr}; fn main() { // 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 // https://blog.rust-lang.org/2019/12/19/Rust-1.40.0.html#additions-to-the-standard-library if minor < 40 { println!("cargo:rustc-cfg=no_btreemap_get_key_value"); } // BTreeMap::remove_entry // https://blog.rust-lang.org/2020/07/16/Rust-1.45.0.html#library-changes if minor < 45 { println!("cargo:rustc-cfg=no_btreemap_remove_entry"); } } fn rustc_minor_version() -> Option { 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() }