rust/hgcli/build.rs

mq: avoid a silly conversion from binary nodeid to hex

We generally deal with binary nodeids in code. In this case the hex
nodeid was passed to strip.checksubstate() where it was passed to
repo.__getitem__, which of course accepts a binary nodeid.

Differential Revision: https://phab.mercurial-scm.org/D3141

// build.rs -- Configure build environment for `hgcli` Rust package.
//
// Copyright 2017 Gregory Szorc <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

use std::collections::HashMap;
use std::env;
use std::path::Path;
use std::process::Command;

struct PythonConfig {
    python: String,
    config: HashMap<String, String>,
}

fn get_python_config() -> PythonConfig {
    // The python27-sys crate exports a Cargo variable defining the full
    // path to the interpreter being used.
    let python = env::var("DEP_PYTHON27_PYTHON_INTERPRETER").expect(
        "Missing DEP_PYTHON27_PYTHON_INTERPRETER; bad python27-sys crate?",
    );

    if !Path::new(&python).exists() {
        panic!(
            "Python interpreter {} does not exist; this should never happen",
            python
        );
    }

    // This is a bit hacky but it gets the job done.
    let separator = "SEPARATOR STRING";

    let script = "import sysconfig; \
c = sysconfig.get_config_vars(); \
print('SEPARATOR STRING'.join('%s=%s' % i for i in c.items()))";

    let mut command = Command::new(&python);
    command.arg("-c").arg(script);

    let out = command.output().unwrap();

    if !out.status.success() {
        panic!(
            "python script failed: {}",
            String::from_utf8_lossy(&out.stderr)
        );
    }

    let stdout = String::from_utf8_lossy(&out.stdout);
    let mut m = HashMap::new();

    for entry in stdout.split(separator) {
        let mut parts = entry.splitn(2, "=");
        let key = parts.next().unwrap();
        let value = parts.next().unwrap();
        m.insert(String::from(key), String::from(value));
    }

    PythonConfig {
        python: python,
        config: m,
    }
}

#[cfg(not(target_os = "windows"))]
fn have_shared(config: &PythonConfig) -> bool {
    match config.config.get("Py_ENABLE_SHARED") {
        Some(value) => value == "1",
        None => false,
    }
}

#[cfg(target_os = "windows")]
fn have_shared(config: &PythonConfig) -> bool {
    use std::path::PathBuf;

    // python27.dll should exist next to python2.7.exe.
    let mut dll = PathBuf::from(&config.python);
    dll.pop();
    dll.push("python27.dll");

    return dll.exists();
}

const REQUIRED_CONFIG_FLAGS: [&str; 2] = ["Py_USING_UNICODE", "WITH_THREAD"];

fn main() {
    let config = get_python_config();

    println!("Using Python: {}", config.python);
    println!("cargo:rustc-env=PYTHON_INTERPRETER={}", config.python);

    let prefix = config.config.get("prefix").unwrap();

    println!("Prefix: {}", prefix);

    // TODO Windows builds don't expose these config flags. Figure out another
    // way.
    #[cfg(not(target_os = "windows"))]
    for key in REQUIRED_CONFIG_FLAGS.iter() {
        let result = match config.config.get(*key) {
            Some(value) => value == "1",
            None => false,
        };

        if !result {
            panic!("Detected Python requires feature {}", key);
        }
    }

    // We need a Python shared library.
    if !have_shared(&config) {
        panic!("Detected Python lacks a shared library, which is required");
    }

    let ucs4 = match config.config.get("Py_UNICODE_SIZE") {
        Some(value) => value == "4",
        None => false,
    };

    if !ucs4 {
        #[cfg(not(target_os = "windows"))]
        panic!("Detected Python doesn't support UCS-4 code points");
    }
}