lean-sys 0.0.4

Bindings to Lean 4's C API
Documentation 
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use std::path::PathBuf;
use std::process::Command;

fn main() {
    if let Ok(docs_rs) = std::env::var("DOCS_RS") {
        // Detected build on `docs.rs`, so skip trying to link in Lean and just build docs
        if docs_rs == "1" {
            return
        }
    }

    // Step 1: Get lean directory
    // TODO: support overriding lean command and/or directory via environment variables?
    let lean_output = Command::new("lean")
        .args(["--print-prefix"])
        .output()
        .expect("Failed to execute lean");
    if !lean_output.status.success() {
        panic!(
            "Command \"lean --print-prefix\" exited unsuccessfully: error {}",
            lean_output.status
        );
    }
    let mut lean_dir = PathBuf::from(String::from_utf8(lean_output.stdout)
        .expect("Path returned by \"lean --print-prefix\" is invalid UTF-8; this is currently not supported")
        .trim());
    if cfg!(target_os = "windows") {
        lean_dir.push("bin")
    } else {
        // Default to Unix-like, of course
        lean_dir.push("lib/lean")
    }

    // Step 2: check libleanshared.so/libleanshared.dylib/libleanshared.dll is actually there, just for cleaner error messages
    let mut shared_lib = lean_dir.clone();
    let exists = if cfg!(target_os = "windows") {
        shared_lib.push("libleanshared.dll");
        shared_lib.exists()
    } else if cfg!(target_os = "macos") {
        shared_lib.push("libleanshared.dylib");
        shared_lib.exists()
    } else if cfg!(unix) {
        shared_lib.push("libleanshared.so");
        shared_lib.exists()
    } else {
        true
    };
    if !exists {
        panic!(
            "{} was not found. We errored, as this would probably cause a linking failure later",
            shared_lib.display()
        );
    }

    // Step 3: actually link with the library
    println!("cargo:rustc-link-search={}", lean_dir.display());
    println!("cargo:rustc-link-lib=leanshared");
    println!("cargo:rustc-link-arg=-Wl,-rpath,{}", lean_dir.display());
}