Haibo Huang | b0dbc76 | 2020-10-28 22:33:04 -0700 | [diff] [blame] | 1 | use std::env; |
| 2 | use std::process::Command; |
| 3 | use std::str; |
| 4 | |
| 5 | // The rustc-cfg strings below are *not* public API. Please let us know by |
| 6 | // opening a GitHub issue if your build environment requires some way to enable |
| 7 | // these cfgs other than by executing our build script. |
| 8 | fn main() { |
| 9 | let minor = match rustc_minor_version() { |
| 10 | Some(minor) => minor, |
| 11 | None => return, |
| 12 | }; |
| 13 | |
| 14 | // Function-like procedural macros in expressions, patterns, and statements |
| 15 | // stabilized in Rust 1.45: |
| 16 | // https://blog.rust-lang.org/2020/07/16/Rust-1.45.0.html#stabilizing-function-like-procedural-macros-in-expressions-patterns-and-statements |
| 17 | if minor < 45 { |
| 18 | println!("cargo:rustc-cfg=need_proc_macro_hack"); |
| 19 | } |
| 20 | } |
| 21 | |
| 22 | fn rustc_minor_version() -> Option<u32> { |
| 23 | let rustc = env::var_os("RUSTC")?; |
| 24 | let output = Command::new(rustc).arg("--version").output().ok()?; |
| 25 | let version = str::from_utf8(&output.stdout).ok()?; |
| 26 | let mut pieces = version.split('.'); |
| 27 | if pieces.next() != Some("rustc 1") { |
| 28 | return None; |
| 29 | } |
| 30 | pieces.next()?.parse().ok() |
| 31 | } |