fix: Cleanup the autoloader from temporary variables (#866)

The goal here is to reduce the "footprint" of PHP-Scoper and avoid
introducing unnecessary conflicts by overriding potential variables.

Author: theofidry

src/Autoload/ScoperAutoloadGenerator.php

@@ -89,6 +89,42 @@ public function dump(): string
                 // scoper-autoload.php @generated by PhpScoper
 
                 namespace {
+                    \$loader = (static function () {
+                        // Backup the autoloaded Composer files
+                        if (isset(\$GLOBALS['__composer_autoload_files'])) {
+                            \$existingComposerAutoloadFiles = \$GLOBALS['__composer_autoload_files'];
+                        }
+
+                        \$loader = require_once __DIR__.'/autoload.php';
+                        // Ensure InstalledVersions is available
+                        \$installedVersionsPath = __DIR__.'/composer/InstalledVersions.php';
+                        if (file_exists(\$installedVersionsPath)) require_once \$installedVersionsPath;
+
+                        // Restore the backup
+                        if (isset(\$existingComposerAutoloadFiles)) {
+                            \$GLOBALS['__composer_autoload_files'] = \$existingComposerAutoloadFiles;
+                        } else {
+                            unset(\$GLOBALS['__composer_autoload_files']);
+                        }
+
+                        return \$loader;
+                    })();
+                }
+
+                {$statements}
+
+                namespace {
+                    return \$loader;
+                }
+
+                PHP;
+        } else {
+            $dump = <<<PHP
+                <?php
+
+                // scoper-autoload.php @generated by PhpScoper
+
+                \$loader = (static function () {
                     // Backup the autoloaded Composer files
                     if (isset(\$GLOBALS['__composer_autoload_files'])) {
                         \$existingComposerAutoloadFiles = \$GLOBALS['__composer_autoload_files'];
@@ -105,37 +141,9 @@ public function dump(): string
                     } else {
                         unset(\$GLOBALS['__composer_autoload_files']);
                     }
-                }
 
-                {$statements}
-
-                namespace {
                     return \$loader;
-                }
-
-                PHP;
-        } else {
-            $dump = <<<PHP
-                <?php
-
-                // scoper-autoload.php @generated by PhpScoper
-
-                // Backup the autoloaded Composer files
-                if (isset(\$GLOBALS['__composer_autoload_files'])) {
-                    \$existingComposerAutoloadFiles = \$GLOBALS['__composer_autoload_files'];
-                }
-
-                \$loader = require_once __DIR__.'/autoload.php';
-                // Ensure InstalledVersions is available
-                \$installedVersionsPath = __DIR__.'/composer/InstalledVersions.php';
-                if (file_exists(\$installedVersionsPath)) require_once \$installedVersionsPath;
-
-                // Restore the backup
-                if (isset(\$existingComposerAutoloadFiles)) {
-                    \$GLOBALS['__composer_autoload_files'] = \$existingComposerAutoloadFiles;
-                } else {
-                    unset(\$GLOBALS['__composer_autoload_files']);
-                }
+                })();
 
                 {$statements}