Add config option to set if the PHP include path should automatically be used when generating the autoloader

src/Composer/Autoload/AutoloadGenerator.php

@@ -30,6 +30,7 @@ class AutoloadGenerator
         $filesystem = new Filesystem();
         $filesystem->ensureDirectoryExists($config->get('vendor-dir'));
         $vendorPath = strtr(realpath($config->get('vendor-dir')), '\\', '/');
+        $useGlobalIncludePath = (bool) $config->get('use-include-path');
         $targetDir = $vendorPath.'/'.$targetDir;
         $filesystem->ensureDirectoryExists($targetDir);
 
@@ -171,7 +172,7 @@ EOF;
             file_put_contents($targetDir.'/include_paths.php', $includePathFile);
         }
         file_put_contents($vendorPath.'/autoload.php', $this->getAutoloadFile($vendorPathToTargetDirCode, $suffix));
-        file_put_contents($targetDir.'/autoload_real.php', $this->getAutoloadRealFile(true, true, (bool) $includePathFile, $targetDirLoader, $filesCode, $vendorPathCode, $appBaseDirCode, $suffix));
+        file_put_contents($targetDir.'/autoload_real.php', $this->getAutoloadRealFile(true, true, (bool) $includePathFile, $targetDirLoader, $filesCode, $vendorPathCode, $appBaseDirCode, $suffix, $useGlobalIncludePath));
         copy(__DIR__.'/ClassLoader.php', $targetDir.'/ClassLoader.php');
     }
 
@@ -326,7 +327,7 @@ return ComposerAutoloaderInit$suffix::getLoader();
 AUTOLOAD;
     }
 
-    protected function getAutoloadRealFile($usePSR0, $useClassMap, $useIncludePath, $targetDirLoader, $filesCode, $vendorPathCode, $appBaseDirCode, $suffix)
+    protected function getAutoloadRealFile($usePSR0, $useClassMap, $useIncludePath, $targetDirLoader, $filesCode, $vendorPathCode, $appBaseDirCode, $suffix, $useGlobalIncludePath)
     {
         // TODO the class ComposerAutoloaderInit should be revert to a closure
         // when APC has been fixed:
@@ -403,6 +404,13 @@ PSR0;
 CLASSMAP;
         }
 
+        if ($useGlobalIncludePath) {
+            $file .= <<<'INCLUDEPATH'
+        $loader->setUseIncludePath(true);
+
+INCLUDEPATH;
+        }
+
         if ($targetDirLoader) {
             $file .= <<<REGISTER_AUTOLOAD
         spl_autoload_register(array('ComposerAutoloaderInit$suffix', 'autoload'), true, true);

src/Composer/Command/ConfigCommand.php

@@ -246,6 +246,10 @@ EOT
                 function ($val) { return true; },
                 function ($val) { return $val !== 'false' && (bool) $val; }
             ),
+            'use-include-path' => array(
+                function ($val) { return true; },
+                function ($val) { return $val !== 'false' && (bool) $val; }
+            ),
         );
         $multiConfigValues = array(
             'github-protocols' => array(

src/Composer/Config.php

@@ -31,6 +31,7 @@ class Config
         'cache-files-dir' => '{$cache-dir}/files',
         'cache-repo-dir' => '{$cache-dir}/repo',
         'cache-vcs-dir' => '{$cache-dir}/vcs',
+        'use-include-path' => false,
     );
 
     public static $defaultRepositories = array(

tests/Composer/Test/Autoload/AutoloadGeneratorTest.php

@@ -40,13 +40,26 @@ class AutoloadGeneratorTest extends TestCase
         $this->ensureDirectoryExistsAndClear($this->vendorDir);
 
         $this->config = $this->getMock('Composer\Config');
-        $this->config->expects($this->any())
+
+        $this->config->expects($this->at(0))
             ->method('get')
             ->with($this->equalTo('vendor-dir'))
             ->will($this->returnCallback(function () use ($that) {
                 return $that->vendorDir;
             }));
 
+        $this->config->expects($this->at(1))
+            ->method('get')
+            ->with($this->equalTo('vendor-dir'))
+            ->will($this->returnCallback(function () use ($that) {
+                return $that->vendorDir;
+            }));
+
+        $this->config->expects($this->at(2))
+            ->method('get')
+            ->with($this->equalTo('use-include-path'))
+            ->will($this->returnValue(false));
+
         $this->dir = getcwd();
         chdir($this->workingDir);