Fix autoloading on PHP 5.6 (#11285)

* Add a CI check to ensure the autoloader can run on php5.6+

* Fix autoloading on PHP 5.6

.github/workflows/autoloader.yml

@@ -0,0 +1,40 @@
+name: "Autoloader"
+
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+
+permissions:
+  contents: read
+
+jobs:
+  tests:
+    name: "Autoloader"
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: "Checkout"
+        uses: "actions/checkout@v3"
+
+      - name: "Install Composer dependencies"
+        run: "composer config platform --unset && composer install"
+
+      - name: "Dump autoloader in the test directory using latest Composer"
+        run: "./bin/composer install -d tests/Composer/Test/Autoload/MinimumVersionSupport"
+
+      - name: "Install oldest supported PHP version for autoloader"
+        uses: "shivammathur/setup-php@v2"
+        with:
+          coverage: "none"
+          extensions: "intl, zip"
+          ini-values: "memory_limit=-1"
+          php-version: "5.6"
+
+      - name: "Check the autoloader can be executed"
+        run: "php main.php"
+        working-directory: tests/Composer/Test/Autoload/MinimumVersionSupport

src/Composer/Autoload/AutoloadGenerator.php

@@ -1029,7 +1029,7 @@ REGISTER_LOADER;
             }
         }, null, null);
         foreach (\$filesToLoad as \$fileIdentifier => \$file) {
-            (\$requireFile)(\$fileIdentifier, \$file);
+            \$requireFile(\$fileIdentifier, \$file);
         }
 
 

src/Composer/Autoload/ClassLoader.php

@@ -429,7 +429,8 @@ class ClassLoader
     public function loadClass($class)
     {
         if ($file = $this->findFile($class)) {
-            (self::$includeFile)($file);
+            $includeFile = self::$includeFile;
+            $includeFile($file);
 
             return true;
         }
@@ -560,7 +561,10 @@ class ClassLoader
         return false;
     }
 
-    private static function initializeIncludeClosure(): void
+    /**
+     * @return void
+     */
+    private static function initializeIncludeClosure()
     {
         if (self::$includeFile !== null) {
             return;

tests/Composer/Test/Autoload/Fixtures/autoload_real_files_by_dependency.php

@@ -40,7 +40,7 @@ class ComposerAutoloaderInitFilesAutoloadOrder
             }
         }, null, null);
         foreach ($filesToLoad as $fileIdentifier => $file) {
-            ($requireFile)($fileIdentifier, $file);
+            $requireFile($fileIdentifier, $file);
         }
 
         return $loader;

tests/Composer/Test/Autoload/Fixtures/autoload_real_functions.php

@@ -40,7 +40,7 @@ class ComposerAutoloaderInitFilesAutoload
             }
         }, null, null);
         foreach ($filesToLoad as $fileIdentifier => $file) {
-            ($requireFile)($fileIdentifier, $file);
+            $requireFile($fileIdentifier, $file);
         }
 
         return $loader;

tests/Composer/Test/Autoload/Fixtures/autoload_real_functions_with_include_paths.php

@@ -44,7 +44,7 @@ class ComposerAutoloaderInitFilesAutoload
             }
         }, null, null);
         foreach ($filesToLoad as $fileIdentifier => $file) {
-            ($requireFile)($fileIdentifier, $file);
+            $requireFile($fileIdentifier, $file);
         }
 
         return $loader;

tests/Composer/Test/Autoload/Fixtures/autoload_real_target_dir.php

@@ -42,7 +42,7 @@ class ComposerAutoloaderInitTargetDir
             }
         }, null, null);
         foreach ($filesToLoad as $fileIdentifier => $file) {
-            ($requireFile)($fileIdentifier, $file);
+            $requireFile($fileIdentifier, $file);
         }
 
         return $loader;

tests/Composer/Test/Autoload/MinimumVersionSupport/Foo.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Test;
+
+class Foo
+{
+    /**
+     * @return void
+     */
+    public static function test()
+    {
+        echo 'psr-4 autoloading: OK'.PHP_EOL;
+    }
+}

tests/Composer/Test/Autoload/MinimumVersionSupport/composer.json

@@ -0,0 +1,11 @@
+{
+    "name": "root/pkg",
+    "autoload": {
+        "files": [
+            "test.php"
+        ],
+        "psr-4": {
+            "Test\\": "."
+        }
+    }
+}

tests/Composer/Test/Autoload/MinimumVersionSupport/main.php

@@ -0,0 +1,9 @@
+<?php
+
+include 'vendor/autoload.php';
+
+Test\Foo::test();
+
+if (Composer\InstalledVersions::isInstalled('root/pkg')) {
+    echo 'isInstalled: OK'.PHP_EOL;
+}

tests/Composer/Test/Autoload/MinimumVersionSupport/test.php

@@ -0,0 +1,3 @@
+<?php
+
+echo 'files autoloading: OK'.PHP_EOL;