Issue #3126566 by greg.1.anderson, jungle, tedbow, hussainweb, Kristen Pol, alexpott: Allow Drupal to work with Composer 2

Author: catch

AllowedPackages.php

@@ -3,6 +3,7 @@
 namespace Drupal\Composer\Plugin\Scaffold;
 
 use Composer\Composer;
+use Composer\DependencyResolver\Operation\OperationInterface;
 use Composer\Installer\PackageEvent;
 use Composer\IO\IOInterface;
 use Composer\Package\PackageInterface;
@@ -96,8 +97,12 @@ public function getAllowedPackages() {
    */
   public function event(PackageEvent $event) {
     $operation = $event->getOperation();
-    // Determine the package.
-    $package = $operation->getJobType() == 'update' ? $operation->getTargetPackage() : $operation->getPackage();
+    // Determine the package. Later, in evaluateNewPackages(), we will report
+    // which of the newly-installed packages have scaffold operations, and
+    // whether or not they are allowed to scaffold by the allowed-packages
+    // option in the root-level composer.json file.
+    $operationType = $this->getOperationType($operation);
+    $package = $operationType === 'update' ? $operation->getTargetPackage() : $operation->getPackage();
     if (ScaffoldOptions::hasOptions($package->getExtra())) {
       $this->newPackages[$package->getName()] = $package;
     }
@@ -176,6 +181,26 @@ protected function evaluateNewPackages(array $allowed_packages) {
     return $allowed_packages;
   }
 
+  /**
+   * Determine the type of the provided operation.
+   *
+   * Adjusts API used for Composer 1 or Composer 2.
+   *
+   * @param \Composer\DependencyResolver\Operation\OperationInterface $operation
+   *   The operation object.
+   *
+   * @return string
+   *   The operation type.
+   */
+  protected function getOperationType(OperationInterface $operation) {
+    // Use Composer 2 method.
+    if (method_exists($operation, 'getOperationType')) {
+      return $operation->getOperationType();
+    }
+    // Fallback to Composer 1 method.
+    return $operation->getJobType();
+  }
+
   /**
    * Retrieves a package from the current composer process.
    *

Plugin.php

@@ -60,6 +60,18 @@ public function activate(Composer $composer, IOInterface $io) {
     $this->requireWasCalled = FALSE;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function deactivate(Composer $composer, IOInterface $io) {
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function uninstall(Composer $composer, IOInterface $io) {
+  }
+
   /**
    * {@inheritdoc}
    */

composer.json

@@ -6,7 +6,7 @@
   "homepage": "https://www.drupal.org/project/drupal",
   "license": "GPL-2.0-or-later",
   "require": {
-    "composer-plugin-api": "^1.0.0",
+    "composer-plugin-api": "^1 || ^2",
     "php": ">=7.0.8"
   },
   "conflict": {