rust 9 lines · 1 tab

Build scripts (build.rs) for compile-time code generation

Marcus Chen Jan 2026

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// build.rs
fn main() {
    println!("cargo:rerun-if-changed=build.rs");

    let version = env!("CARGO_PKG_VERSION");
    println!("cargo:rustc-env=BUILD_VERSION={}", version);

    // Could generate code, compile C, etc.
}

1 file · rust Explain with highlit

A build.rs file runs before compiling your crate, enabling code generation, FFI binding generation, or environment checks. I use build scripts to generate Rust code from proto files (with prost), compile C libraries, or set cfg flags based on the target platform. The script communicates with cargo via println!("cargo:...") directives. For example, println!("cargo:rerun-if-changed=proto") tells cargo when to re-run. Build scripts have access to the crate's manifest and can depend on build-time-only crates. They're powerful but add complexity, so I use them judiciously. For code gen, they're often the cleanest solution.

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