astrodynamics 0.6.3

// Build script.
//
// In normal builds this is a no-op — astrodynamics ships as a pure-Rust crate
// and downstream users compile no C++.
//
// Under the `sgp4-debug-oracle` feature (development only) we compile the
// Vallado C++ reference implementation as a static lib so the test suite can
// dump the C++ elsetrec field-by-field and diff against our pure-Rust port.
// This is purely a debug aid; the feature is off by default and not part of
// the published API.

fn main() {
    let oracle_enabled = std::env::var("CARGO_FEATURE_SGP4_DEBUG_ORACLE").is_ok();
    if !oracle_enabled {
        return;
    }

    // The Vallado C++ source lives only in the git checkout — it is excluded
    // from the published tarball to keep the crate pure-Rust at the surface.
    // If a user enables `--features sgp4-debug-oracle` on a tarball-installed
    // copy of the crate, the source files won't be present. Skip gracefully
    // with a clear message instead of hard-failing the build.
    if !std::path::Path::new("tests/cpp/SGP4.cpp").exists() {
        println!(
            "cargo:warning=astrodynamics: the `sgp4-debug-oracle` feature requires \
             the Vallado C++ source files in tests/cpp/, which are excluded from \
             the published crate. Clone the repo at \
             https://github.com/neilberkman/astrodynamics to use this feature."
        );
        return;
    }

    println!("cargo:rerun-if-changed=tests/cpp/SGP4.cpp");
    println!("cargo:rerun-if-changed=tests/cpp/SGP4.h");
    println!("cargo:rerun-if-changed=tests/cpp/sgp4_dump_wrapper.cpp");

    let mut build = cc::Build::new();
    build
        .cpp(true)
        .file("tests/cpp/SGP4.cpp")
        .file("tests/cpp/sgp4_dump_wrapper.cpp")
        .include("tests/cpp")
        .flag_if_supported("-std=c++11")
        .flag_if_supported("-w")
        // CRITICAL: clang ≥14 enables FP contraction (a*b+c → fma) by default
        // on macOS aarch64. Rust never auto-contracts. The Vallado port was
        // written assuming non-FMA arithmetic. The Python sgp4 PyPI wheel
        // (which generated the JSON fixture) is gcc-built and also non-FMA.
        // Disable FP contraction here so this oracle matches the JSON fixture
        // AND the pure-Rust port bit-for-bit.
        .flag_if_supported("-ffp-contract=off");

    // macOS: BSD `ar` doesn't accept the `-D` flag that newer cc-rs passes
    // for deterministic archives. Use libtool, which cc-rs has special-case
    // logic for and which is the platform-native static archiver on macOS.
    // Compile to object files only, then archive ourselves. cc-rs on
    // macOS has trouble auto-detecting the right archiver — newer versions
    // pass `-D` to BSD ar (not supported), and passing `libtool` doesn't
    // trigger libtool-style argument formatting.
    let objects = build.compile_intermediates();

    let out_dir = std::env::var("OUT_DIR").expect("OUT_DIR set by cargo");
    let lib_path = std::path::Path::new(&out_dir).join("libsgp4_oracle_cpp.a");

    #[cfg(target_os = "macos")]
    {
        let mut cmd = std::process::Command::new("libtool");
        cmd.arg("-static")
            .arg("-no_warning_for_no_symbols")
            .arg("-o")
            .arg(&lib_path);
        for obj in &objects {
            cmd.arg(obj);
        }
        let status = cmd
            .status()
            .expect("failed to invoke libtool to archive C++ objects");
        assert!(status.success(), "libtool failed: {:?}", status);
    }

    #[cfg(not(target_os = "macos"))]
    {
        let mut cmd = std::process::Command::new("ar");
        cmd.arg("rcs").arg(&lib_path);
        for obj in &objects {
            cmd.arg(obj);
        }
        let status = cmd
            .status()
            .expect("failed to invoke ar to archive C++ objects");
        assert!(status.success(), "ar failed: {:?}", status);
    }

    println!("cargo:rustc-link-search=native={}", out_dir);
    println!("cargo:rustc-link-lib=static=sgp4_oracle_cpp");
    println!("cargo:rustc-link-lib=dylib=c++");
}