extern crate version_check; use std::env; use version_check::is_min_version; fn main() { // Switch on for versions that have Error::source // As introduced by https://github.com/rust-lang/rust/pull/53533 if is_min_version("1.30").unwrap_or(false) { println!("cargo:rustc-cfg=has_error_source"); } if is_min_version("1.42").unwrap_or(false) { println!("cargo:rustc-cfg=has_error_description_deprecated"); } // So we can get the build profile for has_backtrace_depending_on_env test if let Ok(profile) = env::var("PROFILE") { println!("cargo:rustc-cfg=build={:?}", profile); } }