built provides a crate with information from the time it was built.

built is used as a build-time dependency to collect various information about the build-environment, serialize this information into Rust-code and provide that to the crate. The information collected by built include:

• Various metadata like version, authors, homepage etc. as set by Cargo.toml
• The tag or commit id if the crate was being compiled from within a Git repository.
• The values of CARGO_CFG_* build script environment variables, like CARGO_CFG_TARGET_OS and CARGO_CFG_TARGET_ARCH.
• The features the crate was compiled with.
• The various dependencies, dependencies of dependencies and their versions Cargo ultimately chose to compile.
• The presence of a CI-platform like Github Actions, Travis CI and AppVeyor.
• The compiler and it's version; the documentation-generator and it's version.

See the example or the docs for more information.

---

// In build.rs

fn main() {
    built::write_built_file().expect("Failed to acquire build-time information")
}

// In lib.rs or main.rs

// Include the generated-file as a separate module
pub mod built_info {
    include!(concat!(env!("OUT_DIR"), "/built.rs"));
}

println!(
    "This is version {}, built for {} by {}.",
    built_info::PKG_VERSION,
    built_info::TARGET,
    built_info::RUSTC_VERSION
);

match built_info::CI_PLATFORM {
    None => print!("It seems I've not been built on a continuous integration platform,"),
    Some(ci) => print!("I've been built on CI-platform {},", ci),
}

if built::util::detect_ci().is_some() {
    println!(" but I'm currently executing on one!");
} else {
    println!(" and I'm currently not executing on one!");
}

//....

This is version 0.1.0, built for x86_64-unknown-linux-gnu by rustc 1.43.1 (8d69840ab 2020-05-04).

I was built from git 0.4.1-10-gca2af4f, commit ca2af4f11bb8f4f6421c4cccf428bf4862573daf; the working directory was "dirty". The branch was refs/heads/master.

I was built for a x86_64-CPU, which is a little-endian architecture. I was compiled to run on linux (a unix-breed) and my runtime should be gnu.

It seems I've not been built on a continuous integration platform, and I'm currently not executing on one!

I was built with profile "debug", features "" on 2020-05-27 20:14:38 +02:00 (1 seconds ago) using autocfg 1.0.0, bitflags 1.2.1, built 0.4.1, cargo-lock 4.0.1, cc 1.0.54, cfg-if 0.1.10, chrono 0.4.11, example_project 0.1.0, git2 0.13.6, idna 0.2.0, jobserver 0.1.21, libc 0.2.71, libgit2-sys 0.12.6+1.0.0, libz-sys 1.0.25, log 0.4.8, matches 0.1.8, num-integer 0.1.42, num-traits 0.2.11, percent-encoding 2.1.0, pkg-config 0.3.17, proc-macro2 1.0.17, quote 1.0.6, semver 0.10.0, semver 0.9.0, semver-parser 0.7.0, serde 1.0.110, serde_derive 1.0.110, smallvec 1.4.0, syn 1.0.25, time 0.1.43, toml 0.5.6, unicode-bidi 0.3.4, unicode-normalization 0.1.12, unicode-xid 0.2.0, url 2.1.1, vcpkg 0.2.8, winapi 0.3.8, winapi-i686-pc-windows-gnu 0.4.0, winapi-x86_64-pc-windows-gnu 0.4.0