| 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<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() |
| } |