hotpath-meta 0.28.2

Hotpath meta - a version of hotpath used to profile the profiler itself. Not intended for external use.
Documentation 
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// Exports the compiler version (report `meta.rustc`) and the Cargo profile
// (Prometheus `hotpath_build_info`); the crate's only build-script jobs.
fn main() {
    println!("cargo:rerun-if-env-changed=RUSTC");
    println!("cargo:rerun-if-env-changed=RUSTUP_TOOLCHAIN");

    let rustc = std::env::var("RUSTC").unwrap_or_else(|_| "rustc".to_string());
    // "rustc 1.89.0 (29483883e 2025-08-04)" -> "1.89.0"
    let version = std::process::Command::new(rustc)
        .arg("--version")
        .output()
        .ok()
        .and_then(|out| String::from_utf8(out.stdout).ok())
        .and_then(|s| s.split_whitespace().nth(1).map(str::to_string))
        .unwrap_or_default();
    println!("cargo:rustc-env=HOTPATH_META_RUSTC_VERSION={version}");

    println!(
        "cargo:rustc-env=HOTPATH_META_CARGO_PROFILE={}",
        cargo_profile()
    );
}

/// Cargo's `PROFILE` env var only distinguishes `debug` from `release`, so a
/// custom profile (`--profile profiling`) is read off `OUT_DIR`
/// (`target/[<triple>/]<profile>/build/<pkg>-<hash>/out`): the component
/// before `build` is the profile's directory name.
fn cargo_profile() -> String {
    let from_out_dir = std::env::var("OUT_DIR").ok().and_then(|out_dir| {
        let path = std::path::PathBuf::from(out_dir);
        let components: Vec<_> = path
            .components()
            .map(|c| c.as_os_str().to_string_lossy().into_owned())
            .collect();
        let build_idx = components.iter().rposition(|c| c == "build")?;
        components.get(build_idx.checked_sub(1)?).cloned()
    });
    from_out_dir
        .or_else(|| std::env::var("PROFILE").ok())
        .unwrap_or_default()
}