Build swiftmailer as phar

build.php

<?php

$srcRoot = realpath(__DIR__."/vendor/swiftmailer/swiftmailer/lib");
$buildRoot = realpath(__DIR__);
$iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($srcRoot, FilesystemIterator::SKIP_DOTS), RecursiveIteratorIterator::LEAVES_ONLY);

echo "Build SwiftMailer phar\n";

$phar = new Phar($buildRoot.'/swiftmailer.phar', 0, 'swiftmailer.phar');
$phar->buildFromIterator($iterator, $srcRoot);
$phar->setStub($phar->createDefaultStub("swift_required.php"));

exit("Build complete\n");

composer.json

{
    "require": {
        "swiftmailer/swiftmailer": "@stable"
    },
    "config": {
      "preferred-install": "dist"
    },
    "prefer-stable": true,
    "scripts": {
        "post-update-cmd": "php build.php",
        "post-install-cmd": "php build.php"
    }
}