Filter out exclude-from-classmap rules to avoid generating very long regexes, fixes #9487

src/Composer/Autoload/AutoloadGenerator.php

@@ -231,7 +231,7 @@ EOF;
 
         $excluded = null;
         if (!empty($autoloads['exclude-from-classmap'])) {
-            $excluded = '{(' . implode('|', $autoloads['exclude-from-classmap']) . ')}';
+            $excluded = $autoloads['exclude-from-classmap'];
         }
 
         $classMap = array();
@@ -350,8 +350,31 @@ EOF;
         return $classMap;
     }
 
+    /**
+     * @param ?array $excluded
+     */
     private function generateClassMap($dir, $excluded, $namespaceFilter, $autoloadType, $showAmbiguousWarning, array &$scannedFiles)
     {
+        if ($excluded) {
+            // filter excluded patterns here to only use those matching $dir
+            // exclude-from-classmap patterns are all realpath'd so we can only filter them if $dir exists so that realpath($dir) will work
+            // if $dir does not exist, it should anyway not find anything there so no trouble
+            if (file_exists($dir)) {
+                // transform $dir in the same way that exclude-from-classmap patterns are transformed so we can match them against each other
+                $dirMatch = preg_quote(strtr(realpath($dir), '\\', '/'));
+                foreach ($excluded as $index => $pattern) {
+                    // extract the constant string prefix of the pattern here, until we reach a non-escaped regex special character
+                    $pattern = preg_replace('{^(([^.+*?\[^\]$(){}=!<>|:\\\\#-]+|\\\\[.+*?\[^\]$(){}=!<>|:#-])*).*}', '$1', $pattern);
+                    // if the pattern is not a subset or superset of $dir, it is unrelated and we skip it
+                    if (0 !== strpos($pattern, $dirMatch) && 0 !== strpos($dirMatch, $pattern)) {
+                        unset($excluded[$index]);
+                    }
+                }
+            }
+
+            $excluded = $excluded ? '{(' . implode('|', $excluded) . ')}' : null;
+        }
+
         return ClassMapGenerator::createMap($dir, $excluded, $showAmbiguousWarning ? $this->io : null, $namespaceFilter, $autoloadType, $scannedFiles);
     }
 
@@ -458,7 +481,7 @@ EOF;
         if (isset($autoloads['classmap'])) {
             $excluded = null;
             if (!empty($autoloads['exclude-from-classmap'])) {
-                $excluded = '{(' . implode('|', $autoloads['exclude-from-classmap']) . ')}';
+                $excluded = $autoloads['exclude-from-classmap'];
             }
 
             $scannedFiles = array();

src/Composer/Autoload/ClassMapGenerator.php

@@ -51,7 +51,7 @@ class ClassMapGenerator
      * Iterate over all files in the given directory searching for classes
      *
      * @param \Iterator|string $path         The path to search in or an iterator
-     * @param string           $excluded    Regex that matches against the file path that exclude from the classmap.
+     * @param string           $excluded     Regex that matches file paths to be excluded from the classmap
      * @param IOInterface      $io           IO object
      * @param string           $namespace    Optional namespace prefix to filter by
      * @param string           $autoloadType psr-0|psr-4 Optional autoload standard to use mapping rules

tests/Composer/Test/Autoload/AutoloadGeneratorTest.php

@@ -1377,9 +1377,9 @@ EOF;
         $package->setAutoload(array(
             'psr-0' => array('Foo' => '../path/../src'),
             'psr-4' => array('Acme\Foo\\' => '../path/../src-psr4'),
-            'classmap' => array('../classmap'),
+            'classmap' => array('../classmap', '../classmap2/subdir', 'classmap3', 'classmap4'),
             'files' => array('../test.php'),
-            'exclude-from-classmap' => array('./../classmap/excluded'),
+            'exclude-from-classmap' => array('./../classmap/excluded', '../classmap2', 'classmap3/classes.php', 'classmap4/*/classes.php'),
         ));
 
         $this->repository->expects($this->once())
@@ -1388,9 +1388,15 @@ EOF;
 
         $this->fs->ensureDirectoryExists($this->workingDir.'/src/Foo');
         $this->fs->ensureDirectoryExists($this->workingDir.'/classmap/excluded');
+        $this->fs->ensureDirectoryExists($this->workingDir.'/classmap2/subdir');
+        $this->fs->ensureDirectoryExists($this->workingDir.'/working-dir/classmap3');
+        $this->fs->ensureDirectoryExists($this->workingDir.'/working-dir/classmap4/foo/');
         file_put_contents($this->workingDir.'/src/Foo/Bar.php', '<?php namespace Foo; class Bar {}');
         file_put_contents($this->workingDir.'/classmap/classes.php', '<?php namespace Foo; class Foo {}');
         file_put_contents($this->workingDir.'/classmap/excluded/classes.php', '<?php namespace Foo; class Boo {}');
+        file_put_contents($this->workingDir.'/classmap2/subdir/classes.php', '<?php namespace Foo; class Boo2 {}');
+        file_put_contents($this->workingDir.'/working-dir/classmap3/classes.php', '<?php namespace Foo; class Boo3 {}');
+        file_put_contents($this->workingDir.'/working-dir/classmap4/foo/classes.php', '<?php namespace Foo; class Boo4 {}');
         file_put_contents($this->workingDir.'/test.php', '<?php class Foo {}');
 
         $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', true, '_14');