Make sure "roundcube/roundcubemail" install path is always available

Author: mvorisek

composer.json

@@ -19,11 +19,11 @@
     ],
     "require": {
         "php": ">=7.3 <8.4",
-        "composer-plugin-api": "^1.0 || ^2.0",
+        "composer-plugin-api": "^2.1",
         "roundcube/roundcubemail": "*"
     },
     "require-dev": {
-        "composer/composer": "^2.0",
+        "composer/composer": "^2.1",
         "ergebnis/composer-normalize": "^2.13",
         "friendsofphp/php-cs-fixer": "^3.0",
         "phpstan/extension-installer": "^1.1",

src/ExtensionInstaller.php

@@ -2,6 +2,7 @@
 
 namespace Roundcube\Composer;
 
+use Composer\Installer\InstallationManager;
 use Composer\Installer\LibraryInstaller;
 use Composer\Package\PackageInterface;
 use Composer\Package\Version\VersionParser;
@@ -43,15 +44,26 @@ protected function setRoundcubemailInstallPath(InstalledRepositoryInterface $ins
 
     protected function getRoundcubemailInstallPath(): string
     {
+        // install path is not set at composer download phase
+        // never assume any path, but for this known composer behaviour get it from backtrace instead
+        if ($this->roundcubemailInstallPath === null) {
+            $backtrace = debug_backtrace();
+            foreach ($backtrace as $frame) {
+                // relies on https://github.com/composer/composer/blob/2.7.4/src/Composer/Installer/InstallationManager.php#L243
+                if (($frame['object'] ?? null) instanceof InstallationManager
+                    && $frame['function'] === 'downloadAndExecuteBatch'
+                ) {
+                    $this->setRoundcubemailInstallPath($frame['args'][0]);
+                }
+            }
+        }
+
         return $this->roundcubemailInstallPath;
     }
 
     public function getInstallPath(PackageInterface $package)
     {
-        if (
-            !$this->supports($package->getType())
-            || $this->roundcubemailInstallPath === null // install path is not known at download phase
-        ) {
+        if (!$this->supports($package->getType())) {
             return parent::getInstallPath($package);
         }