Function watched_var_os

python27-sys/build.rs:70–73

(key: &str)

];

fn watched_var_os(key: &str) -> Option<OsString> {
    println!("cargo:rerun-if-env-changed={}", key);
    env::var_os(key)
}

/// Examine python's compile flags to pass to cfg by launching
/// the interpreter and printing variables of interest from