Return null for install path for metapackages instead of an empty path which then resolves to the root package's path (#11455)

Fixes #11389

doc/articles/custom-installers.md

@@ -157,9 +157,8 @@ source for the exact signature):
   invoked with the update argument.
 * **uninstall()**, here you can determine the actions that need to be executed
   when the package needs to be removed.
-* **getInstallPath()**, this method should return the location where the
+* **getInstallPath()**, this method should return the absolute path where the
-  package is to be installed, _relative from the location of composer.json._
+  package is to be installed. The path _must not end with a slash._
-  The path _must not end with a slash._
 
 Example:
 

src/Composer/Autoload/AutoloadGenerator.php

@@ -485,10 +485,14 @@ EOF;
                 continue;
             }
             $this->validatePackage($package);
+            $installPath = $installationManager->getInstallPath($package);
+            if ($installPath === null) {
+                continue;
+            }
 
             $packageMap[] = [
                 $package,
-                $installationManager->getInstallPath($package),
+                $installPath,
             ];
         }
 

src/Composer/Command/ShowCommand.php

@@ -332,7 +332,12 @@ EOT
             }
             if ($input->getOption('path')) {
                 $io->write($package->getName(), false);
-                $io->write(' ' . strtok(realpath($composer->getInstallationManager()->getInstallPath($package)), "\r\n"));
+                $path = $composer->getInstallationManager()->getInstallPath($package);
+                if (is_string($path)) {
+                    $io->write(' ' . strtok(realpath($path), "\r\n"));
+                } else {
+                    $io->write(' null');
+                }
 
                 return $exitCode;
             }
@@ -509,7 +514,12 @@ EOT
                             $packageViewData['description'] = $package->getDescription();
                         }
                         if ($writePath) {
-                            $packageViewData['path'] = strtok(realpath($composer->getInstallationManager()->getInstallPath($package)), "\r\n");
+                            $path = $composer->getInstallationManager()->getInstallPath($package);
+                            if (is_string($path)) {
+                                $packageViewData['path'] = strtok(realpath($path), "\r\n");
+                            } else {
+                                $packageViewData['path'] = null;
+                            }
                         }
 
                         $packageIsAbandoned = false;
@@ -635,7 +645,7 @@ EOT
     }
 
     /**
-     * @param array<array{name: string, direct-dependency?: bool, version?: string, latest?: string, latest-status?: string, description?: string|null, path?: string, source?: string|null, homepage?: string|null, warning?: string, abandoned?: bool|string}> $packages
+     * @param array<array{name: string, direct-dependency?: bool, version?: string, latest?: string, latest-status?: string, description?: string|null, path?: string|null, source?: string|null, homepage?: string|null, warning?: string, abandoned?: bool|string}> $packages
      */
     private function printPackages(IOInterface $io, array $packages, string $indent, bool $writeVersion, bool $writeLatest, bool $writeDescription, int $width, int $versionLength, int $nameLength, int $latestLength): void
     {
@@ -669,8 +679,8 @@ EOT
                 }
                 $io->write(' ' . $description, false);
             }
-            if (isset($package['path'])) {
+            if (array_key_exists('path', $package)) {
-                $io->write(' ' . $package['path'], false);
+                $io->write(' '.(is_string($package['path']) ? $package['path'] : 'null'), false);
             }
             $io->write('');
             if (isset($package['warning'])) {
@@ -802,7 +812,12 @@ EOT
         $io->write('<info>source</info>   : ' . sprintf('[%s] <comment>%s</comment> %s', $package->getSourceType(), $package->getSourceUrl(), $package->getSourceReference()));
         $io->write('<info>dist</info>     : ' . sprintf('[%s] <comment>%s</comment> %s', $package->getDistType(), $package->getDistUrl(), $package->getDistReference()));
         if ($installedRepo->hasPackage($package)) {
-            $io->write('<info>path</info>     : ' . sprintf('%s', realpath($this->requireComposer()->getInstallationManager()->getInstallPath($package))));
+            $path = $this->requireComposer()->getInstallationManager()->getInstallPath($package);
+            if (is_string($path)) {
+                $io->write('<info>path</info>     : ' . realpath($path));
+            } else {
+                $io->write('<info>path</info>     : null');
+            }
         }
         $io->write('<info>names</info>    : ' . implode(', ', $package->getNames()));
 
@@ -958,10 +973,15 @@ EOT
         }
 
         if ($installedRepo->hasPackage($package)) {
-            $path = realpath($this->requireComposer()->getInstallationManager()->getInstallPath($package));
+            $path = $this->requireComposer()->getInstallationManager()->getInstallPath($package);
+            if (is_string($path)) {
+                $path = realpath($path);
                 if ($path !== false) {
                     $json['path'] = $path;
                 }
+            } else {
+                $json['path'] = null;
+            }
         }
 
         if ($latestPackage instanceof CompletePackageInterface && $latestPackage->isAbandoned()) {

src/Composer/Command/StatusCommand.php

@@ -99,6 +99,9 @@ EOT
         foreach ($installedRepo->getCanonicalPackages() as $package) {
             $downloader = $dm->getDownloaderForPackage($package);
             $targetDir = $im->getInstallPath($package);
+            if ($targetDir === null) {
+                continue;
+            }
 
             if ($downloader instanceof ChangeReportInterface) {
                 if (is_link($targetDir)) {

src/Composer/Command/ValidateCommand.php

@@ -112,6 +112,9 @@ EOT
             $localRepo = $composer->getRepositoryManager()->getLocalRepository();
             foreach ($localRepo->getPackages() as $package) {
                 $path = $composer->getInstallationManager()->getInstallPath($package);
+                if (null === $path) {
+                    continue;
+                }
                 $file = $path . '/composer.json';
                 if (is_dir($path) && file_exists($file)) {
                     [$errors, $publishErrors, $warnings] = $validator->validate($file, $checkAll, $checkVersion);

src/Composer/Installer/InstallationManager.php

@@ -549,9 +549,9 @@ class InstallationManager
     /**
      * Returns the installation path of a package
      *
-     * @return string           path
+     * @return string|null absolute path to install to, which does not end with a slash, or null if the package does not have anything installed on disk
      */
-    public function getInstallPath(PackageInterface $package): string
+    public function getInstallPath(PackageInterface $package): ?string
     {
         $installer = $this->getInstaller($package->getType());
 

src/Composer/Installer/InstallerInterface.php

@@ -112,7 +112,7 @@ interface InstallerInterface
     /**
      * Returns the absolute installation path of a package.
      *
-     * @return string           absolute path to install to, which MUST not end with a slash
+     * @return string|null absolute path to install to, which MUST not end with a slash, or null if the package does not have anything installed on disk
      */
     public function getInstallPath(PackageInterface $package);
 }

src/Composer/Installer/LibraryInstaller.php

@@ -227,6 +227,8 @@ class LibraryInstaller implements InstallerInterface, BinaryPresenceInterface
 
     /**
      * @inheritDoc
+     *
+     * @return string
      */
     public function getInstallPath(PackageInterface $package)
     {

src/Composer/Installer/MetapackageInstaller.php

@@ -124,9 +124,11 @@ class MetapackageInstaller implements InstallerInterface
 
     /**
      * @inheritDoc
+     *
+     * @return null
      */
     public function getInstallPath(PackageInterface $package)
     {
-        return '';
+        return null;
     }
 }

src/Composer/Installer/ProjectInstaller.php

@@ -115,7 +115,7 @@ class ProjectInstaller implements InstallerInterface
     /**
      * Returns the installation path of a package
      *
-     * @return string           path
+     * @return string configured install path
      */
     public function getInstallPath(PackageInterface $package): string
     {

src/Composer/Package/Locker.php

@@ -473,7 +473,11 @@ class Locker
             return null;
         }
 
-        $path = realpath($this->installationManager->getInstallPath($package));
+        $path = $this->installationManager->getInstallPath($package);
+        if ($path === null) {
+            return null;
+        }
+        $path = realpath($path);
         $sourceType = $package->getSourceType();
         $datetime = null;
 

src/Composer/Plugin/PluginManager.php

@@ -236,8 +236,11 @@ class PluginManager
                 continue;
             }
 
-            $downloadPath = $this->getInstallPath($autoloadPackage, $globalRepo && $globalRepo->hasPackage($autoloadPackage));
+            $installPath = $this->getInstallPath($autoloadPackage, $globalRepo && $globalRepo->hasPackage($autoloadPackage));
-            $autoloads[] = [$autoloadPackage, $downloadPath];
+            if ($installPath === null) {
+                continue;
+            }
+            $autoloads[] = [$autoloadPackage, $installPath];
         }
 
         $map = $generator->parseAutoloads($autoloads, $rootPackage);
@@ -524,9 +527,9 @@ class PluginManager
      *
      * @param bool             $global  Whether this is a global package
      *
-     * @return string Install path
+     * @return string|null Install path
      */
-    private function getInstallPath(PackageInterface $package, bool $global = false): string
+    private function getInstallPath(PackageInterface $package, bool $global = false): ?string
     {
         if (!$global) {
             return $this->composer->getInstallationManager()->getInstallPath($package);