build.rs

/* Copyright (C) 2018 Olivier Goffart <ogoffart@woboq.com>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial
portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

use std::io::prelude::*;
use std::io::BufReader;
use std::path::{Path, PathBuf};
use std::process::Command;

use semver::Version;

fn report_error(_err: &str) -> ! {
    {
        #[cfg(feature = "required")]
        panic!("{}", _err);
        #[cfg(not(feature = "required"))]
        {
            println!("cargo:rustc-cfg=no_qt");
            println!("cargo:FOUND=0");
            println!("cargo:ERROR_MESSAGE={}", _err.escape_debug());
            std::process::exit(0)
        }
    }
}

fn qmake_query(var: &str) -> String {
    let output = match std::env::var("QMAKE") {
        Ok(env_var_value) => Command::new(env_var_value).args(&["-query", var]).output(),
        Err(_env_var_err) => {
            (|| {
                // Some Linux distributions (Fedora, Arch) rename qmake to qmake-qt5.
                // qmake6 is somehow an official alias
                for qmake in &["qmake", "qmake6", "qmake-qt5"] {
                    match Command::new(qmake).args(&["-query", var]).output() {
                        Err(err) if err.kind() == std::io::ErrorKind::NotFound => continue,
                        x => return x,
                    }
                }
                Err(std::io::ErrorKind::NotFound.into())
            })()
        }
    };
    let output = match output {
        Ok(output) => output,
        Err(err) => report_error(&format!(
            "Failed to execute qmake. Make sure 'qmake' is in your path!\n{}",
            err
        )),
    };

    if !output.status.success() {
        report_error(&format!(
            "qmake returned with error:\n{}\n{}",
            std::str::from_utf8(&output.stderr).unwrap_or_default(),
            std::str::from_utf8(&output.stdout).unwrap_or_default()
        ));
    }
    std::str::from_utf8(&output.stdout).expect("UTF-8 conversion failed").trim().to_string()
}

fn open_core_header(
    file: &str,
    qt_include_path: &str,
    qt_library_path: &str,
) -> BufReader<std::fs::File> {
    let cargo_target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();

    let mut path = PathBuf::from(qt_include_path);
    path.push("QtCore");
    path.push(file);
    if cargo_target_os == "macos" {
        if !path.exists() {
            path = Path::new(qt_library_path).join("QtCore.framework/Headers");
            path.push(file);
        }
    }
    let f = match std::fs::File::open(&path) {
        Ok(f) => f,
        Err(e) => report_error(&format!(
            "Cannot open `{:?}`, please make sure that the Qt headers are installed.\n{}",
            path, e
        )),
    };
    BufReader::new(f)
}

// qreal is a double, unless QT_COORD_TYPE says otherwise:
// https://doc.qt.io/qt-5/qtglobal.html#qreal-typedef
fn detect_qreal_size(qt_include_path: &str, qt_library_path: &str) {
    const CONFIG_HEADER: &'static str = "qconfig.h";
    let b = open_core_header(CONFIG_HEADER, qt_include_path, qt_library_path);

    // Find declaration of QT_COORD_TYPE
    for line in b.lines() {
        let line = line.expect("UTF-8 conversion failed for qconfig.h");
        if line.contains("QT_COORD_TYPE") {
            if line.contains("float") {
                println!("cargo:rustc-cfg=qreal_is_float");
                return;
            } else {
                panic!("QT_COORD_TYPE with unknown declaration {}", line);
            }
        }
    }
}

fn detect_version_from_header(qt_include_path: &str, qt_library_path: &str) -> String {
    const VERSION_HEADER: &'static str = "qtcoreversion.h";
    let b = open_core_header(VERSION_HEADER, qt_include_path, qt_library_path);

    // Find declaration of QTCORE_VERSION_STR
    for line in b.lines() {
        let line = line.expect("UTF-8 conversion failed for qtcoreversion.h");
        if line.contains("QTCORE_VERSION_STR") {
            return line.split('\"').nth(1).expect("Parsing QTCORE_VERSION_STR").into();
        }
    }
    panic!("Could not detect Qt version from include paths")
}

fn main() {
    // Simple cfg!(target_* = "...") doesn't work in build scripts the way it does in crate's code.
    // https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-build-scripts
    let cargo_target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();
    let cargo_target_env = std::env::var("CARGO_CFG_TARGET_ENV").unwrap();

    println!("cargo:rerun-if-env-changed=QT_INCLUDE_PATH");
    println!("cargo:rerun-if-env-changed=QT_LIBRARY_PATH");
    let (qt_version, qt_include_path, qt_library_path) = match (
        std::env::var("QT_INCLUDE_PATH").ok().filter(|x| !x.is_empty()),
        std::env::var("QT_LIBRARY_PATH").ok().filter(|x| !x.is_empty()),
    ) {
        (Some(qt_include_path), Some(qt_library_path)) => {
            let qt_version = detect_version_from_header(&qt_include_path, &qt_library_path);
            (qt_version, qt_include_path, qt_library_path)
        }
        (None, None) => {
            println!("cargo:rerun-if-env-changed=QMAKE");
            let qt_version = qmake_query("QT_VERSION");
            let qt_include_path = qmake_query("QT_INSTALL_HEADERS");
            let qt_library_path = qmake_query("QT_INSTALL_LIBS");
            (qt_version, qt_include_path, qt_library_path)
        }
        (Some(_), None) | (None, Some(_)) => {
            panic!("QT_INCLUDE_PATH and QT_LIBRARY_PATH env variable must be either both empty or both set.")
        }
    };
    detect_qreal_size(&qt_include_path, &qt_library_path);
    let qt_version = qt_version.parse::<Version>().expect("Parsing Qt version failed");

    if qt_version < Version::new(5, 6, 0) {
        report_error(&format!("Qt too old. Found version {}, but Qt 5.6 is required.\nIf several versions of Qt are installed, set the PATH or QMAKE environment variable so it finds the correct version", qt_version));
    }

    let mut flags = vec![];
    if cargo_target_os == "macos" {
        flags.push("-F");
        flags.push(&qt_library_path);
    }
    if cargo_target_env == "msvc" {
        // For https://code.qt.io/cgit/qt/qtbase.git/commit/?id=0dc6cc055174a0556f2e41ca269013b3a7056c86
        flags.push("/permissive-");
        // Qt assume UTF-8 encoding
        flags.push("/utf-8");
    }
    if qt_version >= Version::new(6, 0, 0) {
        if cargo_target_env == "msvc" {
            flags.push("/Zc:__cplusplus");
            flags.push("/std:c++17");
        } else {
            flags.push("-std=c++17");
        }
    }
    let mut config = cpp_build::Config::new();
    for f in &flags {
        config.flag(f);
    }
    config.include(&qt_include_path).build("src/lib.rs");

    println!("cargo:VERSION={}", &qt_version);
    println!("cargo:LIBRARY_PATH={}", &qt_library_path);
    println!("cargo:INCLUDE_PATH={}", &qt_include_path);
    println!("cargo:FOUND=1");
    println!("cargo:COMPILE_FLAGS={}", flags.join(";"));

    let macos_lib_search = if cargo_target_os == "macos" { "=framework" } else { "" };
    let vers_suffix =
        if cargo_target_os == "macos" { "".to_string() } else { qt_version.major.to_string() };

    // Windows debug suffix exclusively from MSVC land
    let debug = std::env::var("DEBUG").ok().map_or(false, |s| s == "true");
    let windows_dbg_suffix =
        if debug && (cargo_target_os == "windows") && (cargo_target_env == "msvc") {
            println!("cargo:rustc-link-lib=msvcrtd");
            "d"
        } else {
            ""
        };

    // MinGW and MSVC are not compatible
    if cargo_target_os == "windows" {
        let spec = qmake_query("QMAKE_SPEC");
        if (spec.contains("msvc") && cargo_target_env == "gnu")
            || (spec.contains("g++") && cargo_target_env == "msvc")
        {
            report_error(&format!("Rust target '{}' is not compatible with Qt mkspec '{spec}'. Mixing MinGW and MSVC is not allowed.", std::env::var_os("TARGET").unwrap_or_default().to_string_lossy()));
        }
    }
    if std::env::var("CARGO_CFG_TARGET_FAMILY").as_ref().map(|s| s.as_ref()) == Ok("unix") {
        println!("cargo:rustc-cdylib-link-arg=-Wl,-rpath,{}", &qt_library_path);
    }

    println!("cargo:rustc-link-search{}={}", macos_lib_search, &qt_library_path);

    let link_lib = |lib: &str| {
        println!(
            "cargo:rustc-link-lib{search}=Qt{vers}{lib}{suffix}",
            search = macos_lib_search,
            vers = vers_suffix,
            lib = lib,
            suffix = windows_dbg_suffix
        )
    };
    link_lib("Core");
    link_lib("Gui");
    link_lib("Widgets");
    #[cfg(feature = "qtquick")]
    link_lib("Quick");
    #[cfg(feature = "qtquick")]
    link_lib("Qml");
    #[cfg(feature = "qtwebengine")]
    if (cargo_target_os == "windows") && (cargo_target_env != "msvc") {
        println!("cargo:warning=On Windows, WebEngine module is only available under MSVC 2017 or MSVC2019.");
    } else if qt_version >= Version::new(6, 0, 0) {
        if qt_version < Version::new(6, 2, 0) {
            println!(
                "cargo:warning=WebEngine is not supported on Qt {} yet. It is planned for Qt 6.2.",
                qt_version
            );
        }
        link_lib("WebEngineQuick");
    } else {
        link_lib("WebEngine");
    }
    #[cfg(feature = "qtquickcontrols2")]
    link_lib("QuickControls2");
    #[cfg(feature = "qtmultimedia")]
    link_lib("Multimedia");
    #[cfg(feature = "qtmultimediawidgets")]
    link_lib("MultimediaWidgets");
    #[cfg(feature = "qtsql")]
    link_lib("Sql");
    #[cfg(feature = "qttest")]
    link_lib("Test");
    println!("cargo:rerun-if-changed=src");
}