cbindgen 0.1.20

A tool for generating C bindings to Rust code.
Documentation 
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/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use std::env;
use std::path::Path;
use std::process::Command;
use std::str::from_utf8;

extern crate tempdir;
use self::tempdir::TempDir;

/// Use rustc to expand and pretty print the crate into a single file,
/// removing any macros in the process.
pub fn expand(manifest_path: &Path,
              crate_name: &str,
              version: &str) -> Result<String, String> {
    let cargo = env::var("CARGO").unwrap_or_else(|_| String::from("cargo"));

    // Create a temp directory to use as a target dir for cargo expand, for
    // hygenic purposes.
    let target_dir = TempDir::new("cbindgen-expand")
                             .map_err(|_| format!("couldn't create a temp target directory"))?;

    let mut cmd = Command::new(cargo);
    cmd.env("CARGO_TARGET_DIR", target_dir.path());
    cmd.arg("rustc");
    cmd.arg("--manifest-path");
    cmd.arg(manifest_path);
    cmd.arg("--all-features");
    cmd.arg("-p");
    cmd.arg(&format!("{}:{}", crate_name, version));
    cmd.arg("--");
    cmd.arg("-Z");
    cmd.arg("unstable-options");
    cmd.arg("--pretty=expanded");
    let output = cmd.output().unwrap();

    let src = from_utf8(&output.stdout).unwrap().to_owned();
    let error = from_utf8(&output.stderr).unwrap().to_owned();

    if src.len() == 0 {
        Err(error)
    } else {
        Ok(src)
    }
}