[DependencyInjection] Add ContainerBuilder::willBeAvailable() to help with conditional configuration

Author: nicolas-grekas

CHANGELOG.md

@@ -9,6 +9,7 @@ CHANGELOG
  * Add support for loading autoconfiguration rules via the `#[Autoconfigure]` and `#[AutoconfigureTag]` attributes on PHP 8
  * Add autoconfigurable attributes
  * Add support for per-env configuration in loaders
+ * Add `ContainerBuilder::willBeAvailable()` to help with conditional configuration
 
 5.2.0
 -----

Compiler/AbstractRecursivePass.php

@@ -198,7 +198,7 @@ private function getExpressionLanguage(): ExpressionLanguage
     {
         if (null === $this->expressionLanguage) {
             if (!class_exists(ExpressionLanguage::class)) {
-                throw new LogicException('Unable to use expressions as the Symfony ExpressionLanguage component is not installed.');
+                throw new LogicException('Unable to use expressions as the Symfony ExpressionLanguage component is not installed. Try running "composer require symfony/expression-language".');
             }
 
             $providers = $this->container->getExpressionLanguageProviders();

ContainerBuilder.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\DependencyInjection;
 
+use Composer\InstalledVersions;
 use Psr\Container\ContainerInterface as PsrContainerInterface;
 use Symfony\Component\Config\Resource\ClassExistenceResource;
 use Symfony\Component\Config\Resource\ComposerResource;
@@ -1467,6 +1468,34 @@ public function log(CompilerPassInterface $pass, string $message)
         $this->getCompiler()->log($pass, $this->resolveEnvPlaceholders($message));
     }
 
+    /**
+     * Checks whether a class is available and will remain available in the "no-dev" mode of Composer.
+     *
+     * When parent packages are provided and if any of them is in dev-only mode,
+     * the class will be considered available even if it is also in dev-only mode.
+     */
+    final public static function willBeAvailable(string $package, string $class, array $parentPackages): bool
+    {
+        if (!class_exists($class) && !interface_exists($class, false) && !trait_exists($class, false)) {
+            return false;
+        }
+
+        if (!class_exists(InstalledVersions::class) || !InstalledVersions::isInstalled($package) || InstalledVersions::isInstalled($package, false)) {
+            return true;
+        }
+
+        // the package is installed but in dev-mode only, check if this applies to one of the parent packages too
+
+        $rootPackage = InstalledVersions::getRootPackage()['name'] ?? '';
+        foreach ($parentPackages as $parentPackage) {
+            if ($rootPackage === $parentPackage || (InstalledVersions::isInstalled($parentPackage) && !InstalledVersions::isInstalled($parentPackage, false))) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     /**
      * Gets removed binding ids.
      *