Fix autoload regression with metapackage dependencies (#11481)

fixes #11480

introduced by #11455

src/Composer/Autoload/AutoloadGenerator.php

@@ -473,7 +473,7 @@ EOF;
 
     /**
      * @param PackageInterface[] $packages
-     * @return array<int, array{0: PackageInterface, 1: string}>
+     * @return non-empty-array<int, array{0: PackageInterface, 1: string|null}>
      */
     public function buildPackageMap(InstallationManager $installationManager, PackageInterface $rootPackage, array $packages)
     {
@@ -485,14 +485,9 @@ EOF;
                 continue;
             }
             $this->validatePackage($package);
-            $installPath = $installationManager->getInstallPath($package);
-            if ($installPath === null) {
-                continue;
-            }
-
             $packageMap[] = [
                 $package,
-                $installPath,
+                $installationManager->getInstallPath($package),
             ];
         }
 
@@ -523,7 +518,7 @@ EOF;
     /**
      * Compiles an ordered list of namespace => path mappings
      *
-     * @param array<int, array{0: PackageInterface, 1: string}> $packageMap array of array(package, installDir-relative-to-composer.json)
+     * @param non-empty-array<int, array{0: PackageInterface, 1: string|null}> $packageMap array of array(package, installDir-relative-to-composer.json or null for metapackages)
      * @param RootPackageInterface $rootPackage root package instance
      * @param bool|string[] $filteredDevPackages If an array, the list of packages that must be removed. If bool, whether to filter out require-dev packages
      * @return array
@@ -613,7 +608,7 @@ EOF;
     }
 
     /**
-     * @param array<int, array{0: PackageInterface, 1: string}> $packageMap
+     * @param array<int, array{0: PackageInterface, 1: string|null}> $packageMap
      * @return ?string
      */
     protected function getIncludePathsFile(array $packageMap, Filesystem $filesystem, string $basePath, string $vendorPath, string $vendorPathCode, string $appBaseDirCode)
@@ -623,6 +618,11 @@ EOF;
         foreach ($packageMap as $item) {
             [$package, $installPath] = $item;
 
+            // packages that are not installed cannot autoload anything
+            if (null === $installPath) {
+                continue;
+            }
+
             if (null !== $package->getTargetDir() && strlen($package->getTargetDir()) > 0) {
                 $installPath = substr($installPath, 0, -strlen('/'.$package->getTargetDir()));
             }
@@ -716,7 +716,7 @@ EOF;
     }
 
     /**
-     * @param array<int, array{0: PackageInterface, 1: string}> $packageMap
+     * @param array<int, array{0: PackageInterface, 1: string|null}> $packageMap
      * @param bool|'php-only' $checkPlatform
      * @param string[] $devPackageNames
      * @return ?string
@@ -1149,7 +1149,7 @@ INITIALIZER;
     }
 
     /**
-     * @param array<int, array{0: PackageInterface, 1: string}> $packageMap
+     * @param array<int, array{0: PackageInterface, 1: string|null}> $packageMap
      * @param string $type one of: 'psr-0'|'psr-4'|'classmap'|'files'
      * @return array<int, string>|array<string, array<string>>|array<string, string>
      */
@@ -1160,6 +1160,11 @@ INITIALIZER;
         foreach ($packageMap as $item) {
             [$package, $installPath] = $item;
 
+            // packages that are not installed cannot autoload anything
+            if (null === $installPath) {
+                continue;
+            }
+
             $autoload = $package->getAutoload();
             if ($this->devMode && $package === $rootPackage) {
                 $autoload = array_merge_recursive($autoload, $package->getDevAutoload());
@@ -1249,10 +1254,8 @@ INITIALIZER;
     /**
      * Filters out dev-dependencies
      *
-     * @param array<int, array{0: PackageInterface, 1: string}> $packageMap
-     * @return array<int, array{0: PackageInterface, 1: string}>
-     *
-     * @phpstan-param array<int, array{0: PackageInterface, 1: string}> $packageMap
+     * @param array<int, array{0: PackageInterface, 1: string|null}> $packageMap
+     * @return array<int, array{0: PackageInterface, 1: string|null}>
      */
     protected function filterPackageMap(array $packageMap, RootPackageInterface $rootPackage)
     {
@@ -1305,8 +1308,8 @@ INITIALIZER;
      *
      * Packages of equal weight are sorted alphabetically
      *
-     * @param array<int, array{0: PackageInterface, 1: string}> $packageMap
-     * @return array<int, array{0: PackageInterface, 1: string}>
+     * @param array<int, array{0: PackageInterface, 1: string|null}> $packageMap
+     * @return array<int, array{0: PackageInterface, 1: string|null}>
      */
     protected function sortPackageMap(array $packageMap)
     {

tests/Composer/Test/Autoload/AutoloadGeneratorTest.php

@@ -131,7 +131,11 @@ class AutoloadGeneratorTest extends TestCase
             ->getMock();
         $this->im->expects($this->any())
             ->method('getInstallPath')
-            ->will($this->returnCallback(function ($package): string {
+            ->will($this->returnCallback(function ($package): ?string {
+                if ($package->getType() === 'metapackage') {
+                    return null;
+                }
+
                 $targetDir = $package->getTargetDir();
 
                 return $this->vendorDir.'/'.$package->getName() . ($targetDir ? '/'.$targetDir : '');
@@ -398,6 +402,40 @@ class AutoloadGeneratorTest extends TestCase
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated, even if empty.");
     }
 
+    public function testVendorsAutoloadingWithMetapackages(): void
+    {
+        $package = new RootPackage('root/a', '1.0', '1.0');
+        $package->setRequires([
+            'a/a' => new Link('a', 'a/a', new MatchAllConstraint()),
+        ]);
+
+        $packages = [];
+        $packages[] = $a = new Package('a/a', '1.0', '1.0');
+        $packages[] = $b = new Package('b/b', '1.0', '1.0');
+        $packages[] = $c = new AliasPackage($b, '1.2', '1.2');
+        $a->setAutoload(['psr-0' => ['A' => 'src/', 'A\\B' => 'lib/']]);
+        $b->setAutoload(['psr-0' => ['B\\Sub\\Name' => 'src/']]);
+        $a->setType('metapackage');
+        $a->setRequires([
+            'b/b' => new Link('a/a', 'b/b', new MatchAllConstraint()),
+        ]);
+
+        $this->repository->expects($this->once())
+            ->method('getCanonicalPackages')
+            ->will($this->returnValue($packages));
+
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/composer');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b/src');
+        // creating a/a files to make sure they would be found by autoloader even tho they are technically not
+        // needed as the package is a metapackage, but if it fails to be excluded it would find these
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/src');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/lib');
+
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_5');
+        $this->assertAutoloadFiles('vendors_meta', $this->vendorDir.'/composer');
+        $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated, even if empty.");
+    }
+
     public function testNonDevAutoloadExclusionWithRecursion(): void
     {
         $package = new RootPackage('root/a', '1.0', '1.0');

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

@@ -0,0 +1,10 @@
+<?php
+
+// autoload_namespaces.php @generated by Composer
+
+$vendorDir = dirname(__DIR__);
+$baseDir = dirname($vendorDir);
+
+return array(
+    'B\\Sub\\Name' => array($vendorDir . '/b/b/src'),
+);