Fix handling of metapackages with null paths, and handling of paths which do not have a shortest-path and require an absolute path to be addressed

src/Composer/Repository/FilesystemRepository.php

@@ -159,8 +159,13 @@ class FilesystemRepository extends WritableArrayRepository
                 } else {
                     $lines .= "array(),\n";
                 }
-            } elseif ($key === 'install_path') {
-                $lines .= "__DIR__ . " . var_export('/' . $value, true) . ",\n";
+            } elseif ($key === 'install_path' && is_string($value)) {
+                $fs = new Filesystem();
+                if ($fs->isAbsolutePath($value)) {
+                    $lines .= var_export($value, true) . ",\n";
+                } else {
+                    $lines .= "__DIR__ . " . var_export('/' . $value, true) . ",\n";
+                }
             } else {
                 $lines .= var_export($value, true) . ",\n";
             }

tests/Composer/Test/InstalledVersionsTest.php

@@ -52,6 +52,7 @@ class InstalledVersionsTest extends TestCase
             'foo/impl',
             'foo/impl2',
             'foo/replaced',
+            'meta/package',
         );
         $this->assertSame($names, InstalledVersions::getInstalledPackages());
     }
@@ -74,6 +75,7 @@ class InstalledVersionsTest extends TestCase
             array(true,  '__root__'),
             array(true,  'b/replacer'),
             array(false, 'not/there'),
+            array(true,  'meta/package'),
         );
     }
 
@@ -246,8 +248,8 @@ class InstalledVersionsTest extends TestCase
 
     public function testGetInstallPath()
     {
-        $this->assertSame($this->root . '/./', \Composer\InstalledVersions::getInstallPath('__root__'));
-        $this->assertSame($this->root . '/foo/bar/vendor/woop/woop', \Composer\InstalledVersions::getInstallPath('c/c'));
+        $this->assertSame(realpath($this->root), realpath(\Composer\InstalledVersions::getInstallPath('__root__')));
+        $this->assertSame('/foo/bar/vendor/c/c', \Composer\InstalledVersions::getInstallPath('c/c'));
         $this->assertNull(\Composer\InstalledVersions::getInstallPath('foo/impl'));
     }
 }

tests/Composer/Test/Repository/FilesystemRepositoryTest.php

@@ -12,6 +12,7 @@
 
 namespace Composer\Test\Repository;
 
+use Composer\Package\RootPackageInterface;
 use Composer\Repository\FilesystemRepository;
 use Composer\Test\TestCase;
 use Composer\Json\JsonFile;
@@ -157,12 +158,34 @@ class FilesystemRepositoryTest extends TestCase
         $pkg = $this->getPackage('c/c', '3.0');
         $repository->addPackage($pkg);
 
+        $pkg = $this->getPackage('meta/package', '3.0');
+        $pkg->setType('metapackage');
+        $repository->addPackage($pkg);
+
         $im = $this->getMockBuilder('Composer\Installer\InstallationManager')
             ->disableOriginalConstructor()
             ->getMock();
         $im->expects($this->any())
             ->method('getInstallPath')
-            ->will($this->returnValue('/foo/bar/vendor/woop/woop'));
+            ->will($this->returnCallback(function ($package) use ($dir) {
+                // check for empty paths handling
+                if ($package->getType() === 'metapackage') {
+                    return '';
+                }
+
+                if ($package->getName() === 'c/c') {
+                    // check for absolute paths
+                    return '/foo/bar/vendor/c/c';
+                }
+
+                // check for cwd
+                if ($package instanceof RootPackageInterface) {
+                    return $dir;
+                }
+
+                // check for relative paths
+                return 'vendor/'.$package->getName();
+            }));
 
         $repository->write(true, $im);
         $this->assertSame(require __DIR__.'/Fixtures/installed.php', require $dir.'/installed.php');

tests/Composer/Test/Repository/Fixtures/installed.php

@@ -42,7 +42,7 @@ return array(
             'version' => '1.1.0.0',
             'type' => 'library',
             // @phpstan-ignore-next-line
-            'install_path' => $dir . '/foo/bar/vendor/woop/woop',
+            'install_path' => $dir . '/vendor/a/provider',
             'aliases' => array(),
             'reference' => 'distref-as-no-source',
             'dev_requirement' => false,
@@ -52,7 +52,7 @@ return array(
             'version' => '1.2.0.0',
             'type' => 'library',
             // @phpstan-ignore-next-line
-            'install_path' => $dir . '/foo/bar/vendor/woop/woop',
+            'install_path' => $dir . '/vendor/a/provider2',
             'aliases' => array(
               '1.4',
             ),
@@ -64,7 +64,7 @@ return array(
             'version' => '2.2.0.0',
             'type' => 'library',
             // @phpstan-ignore-next-line
-            'install_path' => $dir . '/foo/bar/vendor/woop/woop',
+            'install_path' => $dir . '/vendor/b/replacer',
             'aliases' => array(),
             'reference' => null,
             'dev_requirement' => false,
@@ -73,8 +73,7 @@ return array(
             'pretty_version' => '3.0',
             'version' => '3.0.0.0',
             'type' => 'library',
-            // @phpstan-ignore-next-line
-            'install_path' => $dir . '/foo/bar/vendor/woop/woop',
+            'install_path' => '/foo/bar/vendor/c/c',
             'aliases' => array(),
             'reference' => null,
             'dev_requirement' => true,
@@ -103,5 +102,14 @@ return array(
                 '^3.0',
             ),
         ),
+        'meta/package' => array(
+            'pretty_version' => '3.0',
+            'version' => '3.0.0.0',
+            'type' => 'metapackage',
+            'install_path' => null,
+            'aliases' => array(),
+            'reference' => null,
+            'dev_requirement' => false,
+        )
     ),
 );