From dafd225a35977d2e6d82cef5582a128147614f98 Mon Sep 17 00:00:00 2001
From: Lars Strojny <lars.strojny@internations.org>
Date: Mon, 14 Sep 2020 21:54:44 +0200
Subject: [PATCH 1/6] Allow to pass a string for apcu-autoloader to set the
 APCu prefix

---
 src/Composer/Autoload/AutoloadGenerator.php   |  8 +--
 src/Composer/Command/DumpAutoloadCommand.php  |  6 +--
 src/Composer/Command/InstallCommand.php       |  6 +--
 src/Composer/Command/RemoveCommand.php        |  6 +--
 src/Composer/Command/RequireCommand.php       |  6 +--
 src/Composer/Command/UpdateCommand.php        |  6 +--
 src/Composer/Installer.php                    |  4 +-
 .../Test/Autoload/AutoloadGeneratorTest.php   | 49 +++++++++++++++++++
 8 files changed, 70 insertions(+), 21 deletions(-)

diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index da4f252b8..619d3b32f 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -53,7 +53,7 @@ class AutoloadGenerator
     private $classMapAuthoritative = false;
 
     /**
-     * @var bool
+     * @var bool|string
      */
     private $apcu = false;
 
@@ -92,11 +92,11 @@ class AutoloadGenerator
     /**
      * Whether or not generated autoloader considers APCu caching.
      *
-     * @param bool $apcu
+     * @param bool|string $apcu
      */
     public function setApcu($apcu)
     {
-        $this->apcu = (bool) $apcu;
+        $this->apcu = is_string($apcu) ? $apcu : (bool) $apcu;
     }
 
     /**
@@ -858,7 +858,7 @@ CLASSMAPAUTHORITATIVE;
         }
 
         if ($this->apcu) {
-            $apcuPrefix = substr(base64_encode(md5(uniqid('', true), true)), 0, -3);
+            $apcuPrefix = is_string($this->apcu) ? $this->apcu : substr(base64_encode(md5(uniqid('', true), true)), 0, -3);
             $file .= <<<APCU
         \$loader->setApcuPrefix('$apcuPrefix');
 
diff --git a/src/Composer/Command/DumpAutoloadCommand.php b/src/Composer/Command/DumpAutoloadCommand.php
index 7449d197c..ee6baabdb 100644
--- a/src/Composer/Command/DumpAutoloadCommand.php
+++ b/src/Composer/Command/DumpAutoloadCommand.php
@@ -33,7 +33,7 @@ class DumpAutoloadCommand extends BaseCommand
                 new InputOption('no-scripts', null, InputOption::VALUE_NONE, 'Skips the execution of all scripts defined in composer.json file.'),
                 new InputOption('optimize', 'o', InputOption::VALUE_NONE, 'Optimizes PSR0 and PSR4 packages to be loaded with classmaps too, good for production.'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize`.'),
-                new InputOption('apcu', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes.'),
                 new InputOption('no-dev', null, InputOption::VALUE_NONE, 'Disables autoload-dev rules.'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
@@ -62,7 +62,7 @@ EOT
 
         $optimize = $input->getOption('optimize') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = $input->getOption('apcu') || $config->get('apcu-autoloader');
+        $apcu = strpos($input, '--apcu') !== false || $config->get('apcu-autoloader');
 
         if ($authoritative) {
             $this->getIO()->write('<info>Generating optimized autoload files (authoritative)</info>');
@@ -77,7 +77,7 @@ EOT
         $generator = $composer->getAutoloadGenerator();
         $generator->setDevMode(!$input->getOption('no-dev'));
         $generator->setClassMapAuthoritative($authoritative);
-        $generator->setApcu($apcu);
+        $generator->setApcu($apcu ? $input->getOption('apcu') ?: true : false);
         $generator->setRunScripts(!$input->getOption('no-scripts'));
         $generator->setIgnorePlatformRequirements($ignorePlatformReqs);
         $numberOfClasses = $generator->dump($config, $localRepo, $package, $installationManager, 'composer', $optimize);
diff --git a/src/Composer/Command/InstallCommand.php b/src/Composer/Command/InstallCommand.php
index f8294c47b..07f388867 100644
--- a/src/Composer/Command/InstallCommand.php
+++ b/src/Composer/Command/InstallCommand.php
@@ -48,7 +48,7 @@ class InstallCommand extends BaseCommand
                 new InputOption('verbose', 'v|vv|vvv', InputOption::VALUE_NONE, 'Shows more details including new commits pulled in when updating packages.'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing an argument sets the APCu prefix)'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
                 new InputArgument('packages', InputArgument::IS_ARRAY | InputArgument::OPTIONAL, 'Should not be provided, use composer require instead to add a given package to composer.json.'),
@@ -102,7 +102,7 @@ EOT
 
         $optimize = $input->getOption('optimize-autoloader') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = $input->getOption('apcu-autoloader') || $config->get('apcu-autoloader');
+        $apcu = strpos($input, '--apcu-autoloader') !== false || $config->get('apcu-autoloader');
 
         $ignorePlatformReqs = $input->getOption('ignore-platform-reqs') ?: ($input->getOption('ignore-platform-req') ?: false);
 
@@ -118,7 +118,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu)
+            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
             ->setIgnorePlatformRequirements($ignorePlatformReqs)
         ;
 
diff --git a/src/Composer/Command/RemoveCommand.php b/src/Composer/Command/RemoveCommand.php
index 53c040412..99be3810b 100644
--- a/src/Composer/Command/RemoveCommand.php
+++ b/src/Composer/Command/RemoveCommand.php
@@ -54,7 +54,7 @@ class RemoveCommand extends BaseCommand
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing a string sets the APCu prefix)'),
             ))
             ->setHelp(
                 <<<EOT
@@ -227,7 +227,7 @@ EOT
         $updateDevMode = !$input->getOption('update-no-dev');
         $optimize = $input->getOption('optimize-autoloader') || $composer->getConfig()->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $composer->getConfig()->get('classmap-authoritative');
-        $apcu = $input->getOption('apcu-autoloader') || $composer->getConfig()->get('apcu-autoloader');
+        $apcu = strpos($input, '--apcu-autoloader') !== false || $composer->getConfig()->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_LISTED_WITH_TRANSITIVE_DEPS_NO_ROOT_REQUIRE;
         $flags = '';
@@ -248,7 +248,7 @@ EOT
             ->setDevMode($updateDevMode)
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu)
+            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateAllowList($packages)
diff --git a/src/Composer/Command/RequireCommand.php b/src/Composer/Command/RequireCommand.php
index 9525b9e77..b1ad95b67 100644
--- a/src/Composer/Command/RequireCommand.php
+++ b/src/Composer/Command/RequireCommand.php
@@ -76,7 +76,7 @@ class RequireCommand extends InitCommand
                 new InputOption('sort-packages', null, InputOption::VALUE_NONE, 'Sorts packages when adding/updating a new dependency'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing a string sets the APCu prefix)'),
             ))
             ->setHelp(
                 <<<EOT
@@ -269,7 +269,7 @@ EOT
         $updateDevMode = !$input->getOption('update-no-dev');
         $optimize = $input->getOption('optimize-autoloader') || $composer->getConfig()->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $composer->getConfig()->get('classmap-authoritative');
-        $apcu = $input->getOption('apcu-autoloader') || $composer->getConfig()->get('apcu-autoloader');
+        $apcu = strpos($input, '--apcu-autoloader') !== false || $composer->getConfig()->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_ONLY_LISTED;
         $flags = '';
@@ -301,7 +301,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu)
+            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateAllowTransitiveDependencies($updateAllowTransitiveDependencies)
diff --git a/src/Composer/Command/UpdateCommand.php b/src/Composer/Command/UpdateCommand.php
index 809db532c..bff37129f 100644
--- a/src/Composer/Command/UpdateCommand.php
+++ b/src/Composer/Command/UpdateCommand.php
@@ -59,7 +59,7 @@ class UpdateCommand extends BaseCommand
                 new InputOption('verbose', 'v|vv|vvv', InputOption::VALUE_NONE, 'Shows more details including new commits pulled in when updating packages.'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump.'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing a string sets the APCu prefix)'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
                 new InputOption('prefer-stable', null, InputOption::VALUE_NONE, 'Prefer stable versions of dependencies.'),
@@ -189,7 +189,7 @@ EOT
 
         $optimize = $input->getOption('optimize-autoloader') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = $input->getOption('apcu-autoloader') || $config->get('apcu-autoloader');
+        $apcu = strpos($input, '--apcu-autoloader') !== false || $config->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_ONLY_LISTED;
         if ($input->getOption('with-all-dependencies')) {
@@ -210,7 +210,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu)
+            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateMirrors($updateMirrors)
diff --git a/src/Composer/Installer.php b/src/Composer/Installer.php
index 535ad8e4c..17d319e00 100644
--- a/src/Composer/Installer.php
+++ b/src/Composer/Installer.php
@@ -1023,12 +1023,12 @@ class Installer
     /**
      * Whether or not generated autoloader considers APCu caching.
      *
-     * @param  bool      $apcuAutoloader
+     * @param  bool|string $apcuAutoloader
      * @return Installer
      */
     public function setApcuAutoloader($apcuAutoloader = false)
     {
-        $this->apcuAutoloader = (bool) $apcuAutoloader;
+        $this->apcuAutoloader = is_string($apcuAutoloader) ? $apcuAutoloader : (bool) $apcuAutoloader;
 
         return $this;
     }
diff --git a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
index ad38b3c8f..fbc2ba86b 100644
--- a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
+++ b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
@@ -823,6 +823,55 @@ EOF;
         $this->assertStringContainsString('$loader->setApcuPrefix(', file_get_contents($this->vendorDir.'/composer/autoload_real.php'));
     }
 
+    public function testClassMapAutoloadingAuthoritativeAndApcuPrefix()
+    {
+        $package = new Package('a', '1.0', '1.0');
+        $package->setRequires(array(
+            new Link('a', 'a/a', new MatchAllConstraint()),
+            new Link('a', 'b/b', new MatchAllConstraint()),
+            new Link('a', 'c/c', new MatchAllConstraint()),
+        ));
+
+        $packages = array();
+        $packages[] = $a = new Package('a/a', '1.0', '1.0');
+        $packages[] = $b = new Package('b/b', '1.0', '1.0');
+        $packages[] = $c = new Package('c/c', '1.0', '1.0');
+        $a->setAutoload(array('psr-4' => array('' => 'src/')));
+        $b->setAutoload(array('psr-4' => array('' => './')));
+        $c->setAutoload(array('psr-4' => array('' => 'foo/')));
+
+        $this->repository->expects($this->once())
+            ->method('getCanonicalPackages')
+            ->will($this->returnValue($packages));
+
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/composer');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/a/a/src');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/b/b');
+        $this->fs->ensureDirectoryExists($this->vendorDir.'/c/c/foo');
+        file_put_contents($this->vendorDir.'/a/a/src/ClassMapFoo.php', '<?php class ClassMapFoo {}');
+        file_put_contents($this->vendorDir.'/b/b/ClassMapBar.php', '<?php class ClassMapBar {}');
+        file_put_contents($this->vendorDir.'/c/c/foo/ClassMapBaz.php', '<?php class ClassMapBaz {}');
+
+        $this->generator->setClassMapAuthoritative(true);
+        $this->generator->setApcu('customPrefix');
+        $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_7');
+
+        $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated.");
+        $this->assertEquals(
+            array(
+                'ClassMapBar' => $this->vendorDir.'/b/b/ClassMapBar.php',
+                'ClassMapBaz' => $this->vendorDir.'/c/c/foo/ClassMapBaz.php',
+                'ClassMapFoo' => $this->vendorDir.'/a/a/src/ClassMapFoo.php',
+                'Composer\\InstalledVersions' => $this->vendorDir.'/composer/InstalledVersions.php',
+            ),
+            include $this->vendorDir.'/composer/autoload_classmap.php'
+        );
+        $this->assertAutoloadFiles('classmap8', $this->vendorDir.'/composer', 'classmap');
+
+        $this->assertStringContainsString('$loader->setClassMapAuthoritative(true);', file_get_contents($this->vendorDir.'/composer/autoload_real.php'));
+        $this->assertStringContainsString('$loader->setApcuPrefix(\'customPrefix\');', file_get_contents($this->vendorDir.'/composer/autoload_real.php'));
+    }
+
     public function testFilesAutoloadGeneration()
     {
         $package = new Package('a', '1.0', '1.0');

From de0085767c3e16a1cae217a3d4ac076fd257f1d6 Mon Sep 17 00:00:00 2001
From: Lars Strojny <lars.strojny@internations.org>
Date: Tue, 15 Sep 2020 12:39:22 +0200
Subject: [PATCH 2/6] Sanitize prefix

---
 src/Composer/Autoload/AutoloadGenerator.php            | 4 ++--
 tests/Composer/Test/Autoload/AutoloadGeneratorTest.php | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index 619d3b32f..cbf3b0aba 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -858,9 +858,9 @@ CLASSMAPAUTHORITATIVE;
         }
 
         if ($this->apcu) {
-            $apcuPrefix = is_string($this->apcu) ? $this->apcu : substr(base64_encode(md5(uniqid('', true), true)), 0, -3);
+            $apcuPrefix = var_export(is_string($this->apcu) ? $this->apcu : substr(base64_encode(md5(uniqid('', true), true)), 0, -3), true);
             $file .= <<<APCU
-        \$loader->setApcuPrefix('$apcuPrefix');
+        \$loader->setApcuPrefix($apcuPrefix);
 
 APCU;
         }
diff --git a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
index fbc2ba86b..0cdc58dda 100644
--- a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
+++ b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
@@ -853,7 +853,7 @@ EOF;
         file_put_contents($this->vendorDir.'/c/c/foo/ClassMapBaz.php', '<?php class ClassMapBaz {}');
 
         $this->generator->setClassMapAuthoritative(true);
-        $this->generator->setApcu('customPrefix');
+        $this->generator->setApcu('custom\'Prefix');
         $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_7');
 
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated.");
@@ -869,7 +869,7 @@ EOF;
         $this->assertAutoloadFiles('classmap8', $this->vendorDir.'/composer', 'classmap');
 
         $this->assertStringContainsString('$loader->setClassMapAuthoritative(true);', file_get_contents($this->vendorDir.'/composer/autoload_real.php'));
-        $this->assertStringContainsString('$loader->setApcuPrefix(\'customPrefix\');', file_get_contents($this->vendorDir.'/composer/autoload_real.php'));
+        $this->assertStringContainsString('$loader->setApcuPrefix(\'custom\\\'Prefix\');', file_get_contents($this->vendorDir.'/composer/autoload_real.php'));
     }
 
     public function testFilesAutoloadGeneration()

From 0b6abf3b9669047e4003ae5fd01fd2ee2cba139f Mon Sep 17 00:00:00 2001
From: Lars Strojny <lars.strojny@internations.org>
Date: Wed, 16 Sep 2020 10:49:00 +0200
Subject: [PATCH 3/6] APCu prefix as a separate option

---
 src/Composer/Autoload/AutoloadGenerator.php     | 17 ++++++++++++-----
 src/Composer/Command/DumpAutoloadCommand.php    |  8 +++++---
 src/Composer/Command/InstallCommand.php         |  7 ++++---
 src/Composer/Command/RemoveCommand.php          |  7 ++++---
 src/Composer/Command/RequireCommand.php         |  7 ++++---
 src/Composer/Command/UpdateCommand.php          |  7 ++++---
 src/Composer/Installer.php                      | 11 +++++++----
 .../Test/Autoload/AutoloadGeneratorTest.php     |  2 +-
 8 files changed, 41 insertions(+), 25 deletions(-)

diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index cbf3b0aba..161e943ae 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -53,10 +53,15 @@ class AutoloadGenerator
     private $classMapAuthoritative = false;
 
     /**
-     * @var bool|string
+     * @var bool
      */
     private $apcu = false;
 
+    /**
+     * @var string|null
+     */
+    private $apcuPrefix;
+
     /**
      * @var bool
      */
@@ -92,11 +97,13 @@ class AutoloadGenerator
     /**
      * Whether or not generated autoloader considers APCu caching.
      *
-     * @param bool|string $apcu
+     * @param bool        $apcu
+     * @param string|null $apcuPrefix
      */
-    public function setApcu($apcu)
+    public function setApcu($apcu, $apcuPrefix = null)
     {
-        $this->apcu = is_string($apcu) ? $apcu : (bool) $apcu;
+        $this->apcu = (bool) $apcu;
+        $this->apcuPrefix = $apcuPrefix !== null ? (string) $apcuPrefix : $apcuPrefix;
     }
 
     /**
@@ -858,7 +865,7 @@ CLASSMAPAUTHORITATIVE;
         }
 
         if ($this->apcu) {
-            $apcuPrefix = var_export(is_string($this->apcu) ? $this->apcu : substr(base64_encode(md5(uniqid('', true), true)), 0, -3), true);
+            $apcuPrefix = var_export(($this->apcuPrefix ?: substr(base64_encode(md5(uniqid('', true), true)), 0, -3)), true);
             $file .= <<<APCU
         \$loader->setApcuPrefix($apcuPrefix);
 
diff --git a/src/Composer/Command/DumpAutoloadCommand.php b/src/Composer/Command/DumpAutoloadCommand.php
index ee6baabdb..500569a25 100644
--- a/src/Composer/Command/DumpAutoloadCommand.php
+++ b/src/Composer/Command/DumpAutoloadCommand.php
@@ -14,6 +14,7 @@ namespace Composer\Command;
 
 use Composer\Plugin\CommandEvent;
 use Composer\Plugin\PluginEvents;
+use Symfony\Component\Console\Input\InputDefinition;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
@@ -33,7 +34,8 @@ class DumpAutoloadCommand extends BaseCommand
                 new InputOption('no-scripts', null, InputOption::VALUE_NONE, 'Skips the execution of all scripts defined in composer.json file.'),
                 new InputOption('optimize', 'o', InputOption::VALUE_NONE, 'Optimizes PSR0 and PSR4 packages to be loaded with classmaps too, good for production.'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize`.'),
-                new InputOption('apcu', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
                 new InputOption('no-dev', null, InputOption::VALUE_NONE, 'Disables autoload-dev rules.'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
@@ -62,7 +64,7 @@ EOT
 
         $optimize = $input->getOption('optimize') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = strpos($input, '--apcu') !== false || $config->get('apcu-autoloader');
+        $apcu = $input->getOption('apcu') || $config->get('apcu-autoloader');
 
         if ($authoritative) {
             $this->getIO()->write('<info>Generating optimized autoload files (authoritative)</info>');
@@ -77,7 +79,7 @@ EOT
         $generator = $composer->getAutoloadGenerator();
         $generator->setDevMode(!$input->getOption('no-dev'));
         $generator->setClassMapAuthoritative($authoritative);
-        $generator->setApcu($apcu ? $input->getOption('apcu') ?: true : false);
+        $generator->setApcu($apcu, $input->getOption('apcu-prefix'));
         $generator->setRunScripts(!$input->getOption('no-scripts'));
         $generator->setIgnorePlatformRequirements($ignorePlatformReqs);
         $numberOfClasses = $generator->dump($config, $localRepo, $package, $installationManager, 'composer', $optimize);
diff --git a/src/Composer/Command/InstallCommand.php b/src/Composer/Command/InstallCommand.php
index 07f388867..cbcb0eae7 100644
--- a/src/Composer/Command/InstallCommand.php
+++ b/src/Composer/Command/InstallCommand.php
@@ -48,7 +48,8 @@ class InstallCommand extends BaseCommand
                 new InputOption('verbose', 'v|vv|vvv', InputOption::VALUE_NONE, 'Shows more details including new commits pulled in when updating packages.'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing an argument sets the APCu prefix)'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
                 new InputArgument('packages', InputArgument::IS_ARRAY | InputArgument::OPTIONAL, 'Should not be provided, use composer require instead to add a given package to composer.json.'),
@@ -102,7 +103,7 @@ EOT
 
         $optimize = $input->getOption('optimize-autoloader') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = strpos($input, '--apcu-autoloader') !== false || $config->get('apcu-autoloader');
+        $apcu = $input->getOption('apcu-autoloader') || $config->get('apcu-autoloader');
 
         $ignorePlatformReqs = $input->getOption('ignore-platform-reqs') ?: ($input->getOption('ignore-platform-req') ?: false);
 
@@ -118,7 +119,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
+            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
             ->setIgnorePlatformRequirements($ignorePlatformReqs)
         ;
 
diff --git a/src/Composer/Command/RemoveCommand.php b/src/Composer/Command/RemoveCommand.php
index 99be3810b..9e2a46b5a 100644
--- a/src/Composer/Command/RemoveCommand.php
+++ b/src/Composer/Command/RemoveCommand.php
@@ -54,7 +54,8 @@ class RemoveCommand extends BaseCommand
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing a string sets the APCu prefix)'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
             ))
             ->setHelp(
                 <<<EOT
@@ -227,7 +228,7 @@ EOT
         $updateDevMode = !$input->getOption('update-no-dev');
         $optimize = $input->getOption('optimize-autoloader') || $composer->getConfig()->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $composer->getConfig()->get('classmap-authoritative');
-        $apcu = strpos($input, '--apcu-autoloader') !== false || $composer->getConfig()->get('apcu-autoloader');
+        $apcu = $input->getOption('apcu-autoloader') ?: $composer->getConfig()->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_LISTED_WITH_TRANSITIVE_DEPS_NO_ROOT_REQUIRE;
         $flags = '';
@@ -248,7 +249,7 @@ EOT
             ->setDevMode($updateDevMode)
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
+            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateAllowList($packages)
diff --git a/src/Composer/Command/RequireCommand.php b/src/Composer/Command/RequireCommand.php
index b1ad95b67..f276b781c 100644
--- a/src/Composer/Command/RequireCommand.php
+++ b/src/Composer/Command/RequireCommand.php
@@ -76,7 +76,8 @@ class RequireCommand extends InitCommand
                 new InputOption('sort-packages', null, InputOption::VALUE_NONE, 'Sorts packages when adding/updating a new dependency'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing a string sets the APCu prefix)'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
             ))
             ->setHelp(
                 <<<EOT
@@ -269,7 +270,7 @@ EOT
         $updateDevMode = !$input->getOption('update-no-dev');
         $optimize = $input->getOption('optimize-autoloader') || $composer->getConfig()->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $composer->getConfig()->get('classmap-authoritative');
-        $apcu = strpos($input, '--apcu-autoloader') !== false || $composer->getConfig()->get('apcu-autoloader');
+        $apcu = $input->getOption('apcu-autoloader') || $composer->getConfig()->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_ONLY_LISTED;
         $flags = '';
@@ -301,7 +302,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
+            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateAllowTransitiveDependencies($updateAllowTransitiveDependencies)
diff --git a/src/Composer/Command/UpdateCommand.php b/src/Composer/Command/UpdateCommand.php
index bff37129f..cd404e95b 100644
--- a/src/Composer/Command/UpdateCommand.php
+++ b/src/Composer/Command/UpdateCommand.php
@@ -59,7 +59,8 @@ class UpdateCommand extends BaseCommand
                 new InputOption('verbose', 'v|vv|vvv', InputOption::VALUE_NONE, 'Shows more details including new commits pulled in when updating packages.'),
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump.'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
-                new InputOption('apcu-autoloader', null, InputOption::VALUE_OPTIONAL, 'Use APCu to cache found/not-found classes (passing a string sets the APCu prefix)'),
+                new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
                 new InputOption('prefer-stable', null, InputOption::VALUE_NONE, 'Prefer stable versions of dependencies.'),
@@ -189,7 +190,7 @@ EOT
 
         $optimize = $input->getOption('optimize-autoloader') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = strpos($input, '--apcu-autoloader') !== false || $config->get('apcu-autoloader');
+        $apcu = $input->getOption('apcu-autoloader') || $config->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_ONLY_LISTED;
         if ($input->getOption('with-all-dependencies')) {
@@ -210,7 +211,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu ? $input->getOption('apcu-autoloader') ?: true : false)
+            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateMirrors($updateMirrors)
diff --git a/src/Composer/Installer.php b/src/Composer/Installer.php
index 17d319e00..50ada1981 100644
--- a/src/Composer/Installer.php
+++ b/src/Composer/Installer.php
@@ -126,6 +126,7 @@ class Installer
     protected $optimizeAutoloader = false;
     protected $classMapAuthoritative = false;
     protected $apcuAutoloader = false;
+    protected $apcuAutoloaderPrefix;
     protected $devMode = false;
     protected $dryRun = false;
     protected $verbose = false;
@@ -307,7 +308,7 @@ class Installer
 
             $this->autoloadGenerator->setDevMode($this->devMode);
             $this->autoloadGenerator->setClassMapAuthoritative($this->classMapAuthoritative);
-            $this->autoloadGenerator->setApcu($this->apcuAutoloader);
+            $this->autoloadGenerator->setApcu($this->apcuAutoloader, $this->apcuAutoloaderPrefix);
             $this->autoloadGenerator->setRunScripts($this->runScripts);
             $this->autoloadGenerator->setIgnorePlatformRequirements($this->ignorePlatformReqs);
             $this->autoloadGenerator->dump($this->config, $localRepo, $this->package, $this->installationManager, 'composer', $this->optimizeAutoloader);
@@ -1023,12 +1024,14 @@ class Installer
     /**
      * Whether or not generated autoloader considers APCu caching.
      *
-     * @param  bool|string $apcuAutoloader
+     * @param  bool        $apcuAutoloader
+     * @param  string|null $apcuAutoloaderPrefix
      * @return Installer
      */
-    public function setApcuAutoloader($apcuAutoloader = false)
+    public function setApcuAutoloader($apcuAutoloader = false, $apcuAutoloaderPrefix = null)
     {
-        $this->apcuAutoloader = is_string($apcuAutoloader) ? $apcuAutoloader : (bool) $apcuAutoloader;
+        $this->apcuAutoloader = $apcuAutoloader;
+        $this->apcuAutoloaderPrefix = $apcuAutoloaderPrefix;
 
         return $this;
     }
diff --git a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
index 0cdc58dda..ece9bb2a0 100644
--- a/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
+++ b/tests/Composer/Test/Autoload/AutoloadGeneratorTest.php
@@ -853,7 +853,7 @@ EOF;
         file_put_contents($this->vendorDir.'/c/c/foo/ClassMapBaz.php', '<?php class ClassMapBaz {}');
 
         $this->generator->setClassMapAuthoritative(true);
-        $this->generator->setApcu('custom\'Prefix');
+        $this->generator->setApcu(true, 'custom\'Prefix');
         $this->generator->dump($this->config, $this->repository, $package, $this->im, 'composer', false, '_7');
 
         $this->assertFileExists($this->vendorDir.'/composer/autoload_classmap.php', "ClassMap file needs to be generated.");

From 7db8b33a9eed6ec9bbd6e0d2943a3949b7521a6e Mon Sep 17 00:00:00 2001
From: Lars Strojny <lars.strojny@internations.org>
Date: Wed, 16 Sep 2020 10:53:55 +0200
Subject: [PATCH 4/6] Restore

---
 src/Composer/Command/RemoveCommand.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Composer/Command/RemoveCommand.php b/src/Composer/Command/RemoveCommand.php
index 9e2a46b5a..8fb49e986 100644
--- a/src/Composer/Command/RemoveCommand.php
+++ b/src/Composer/Command/RemoveCommand.php
@@ -228,7 +228,7 @@ EOT
         $updateDevMode = !$input->getOption('update-no-dev');
         $optimize = $input->getOption('optimize-autoloader') || $composer->getConfig()->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $composer->getConfig()->get('classmap-authoritative');
-        $apcu = $input->getOption('apcu-autoloader') ?: $composer->getConfig()->get('apcu-autoloader');
+        $apcu = $input->getOption('apcu-autoloader') || $composer->getConfig()->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_LISTED_WITH_TRANSITIVE_DEPS_NO_ROOT_REQUIRE;
         $flags = '';

From 6899060f6ee1893d0e205c45120c8cc9264c35fe Mon Sep 17 00:00:00 2001
From: Lars Strojny <lars.strojny@internations.org>
Date: Wed, 16 Sep 2020 10:54:52 +0200
Subject: [PATCH 5/6] Remove superfluous use

---
 src/Composer/Command/DumpAutoloadCommand.php | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/Composer/Command/DumpAutoloadCommand.php b/src/Composer/Command/DumpAutoloadCommand.php
index 500569a25..b5750ed2f 100644
--- a/src/Composer/Command/DumpAutoloadCommand.php
+++ b/src/Composer/Command/DumpAutoloadCommand.php
@@ -14,7 +14,6 @@ namespace Composer\Command;
 
 use Composer\Plugin\CommandEvent;
 use Composer\Plugin\PluginEvents;
-use Symfony\Component\Console\Input\InputDefinition;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;

From 696f27ca833aa152e5f937fe2282175659b713d2 Mon Sep 17 00:00:00 2001
From: Lars Strojny <lars.strojny@internations.org>
Date: Wed, 16 Sep 2020 13:44:51 +0200
Subject: [PATCH 6/6] Enable APCu if prefix is set

---
 src/Composer/Autoload/AutoloadGenerator.php  | 2 +-
 src/Composer/Command/DumpAutoloadCommand.php | 7 ++++---
 src/Composer/Command/InstallCommand.php      | 7 ++++---
 src/Composer/Command/RemoveCommand.php       | 7 ++++---
 src/Composer/Command/RequireCommand.php      | 7 ++++---
 src/Composer/Command/UpdateCommand.php       | 7 ++++---
 6 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index 161e943ae..6ff089bb1 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -865,7 +865,7 @@ CLASSMAPAUTHORITATIVE;
         }
 
         if ($this->apcu) {
-            $apcuPrefix = var_export(($this->apcuPrefix ?: substr(base64_encode(md5(uniqid('', true), true)), 0, -3)), true);
+            $apcuPrefix = var_export(($this->apcuPrefix !== null ? $this->apcuPrefix : substr(base64_encode(md5(uniqid('', true), true)), 0, -3)), true);
             $file .= <<<APCU
         \$loader->setApcuPrefix($apcuPrefix);
 
diff --git a/src/Composer/Command/DumpAutoloadCommand.php b/src/Composer/Command/DumpAutoloadCommand.php
index b5750ed2f..0b2413925 100644
--- a/src/Composer/Command/DumpAutoloadCommand.php
+++ b/src/Composer/Command/DumpAutoloadCommand.php
@@ -34,7 +34,7 @@ class DumpAutoloadCommand extends BaseCommand
                 new InputOption('optimize', 'o', InputOption::VALUE_NONE, 'Optimizes PSR0 and PSR4 packages to be loaded with classmaps too, good for production.'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize`.'),
                 new InputOption('apcu', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
-                new InputOption('apcu-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
+                new InputOption('apcu-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache. Implicitly enables --apcu'),
                 new InputOption('no-dev', null, InputOption::VALUE_NONE, 'Disables autoload-dev rules.'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
@@ -63,7 +63,8 @@ EOT
 
         $optimize = $input->getOption('optimize') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = $input->getOption('apcu') || $config->get('apcu-autoloader');
+        $apcuPrefix = $input->getOption('apcu-prefix');
+        $apcu = $apcuPrefix !== null || $input->getOption('apcu') || $config->get('apcu-autoloader');
 
         if ($authoritative) {
             $this->getIO()->write('<info>Generating optimized autoload files (authoritative)</info>');
@@ -78,7 +79,7 @@ EOT
         $generator = $composer->getAutoloadGenerator();
         $generator->setDevMode(!$input->getOption('no-dev'));
         $generator->setClassMapAuthoritative($authoritative);
-        $generator->setApcu($apcu, $input->getOption('apcu-prefix'));
+        $generator->setApcu($apcu, $apcuPrefix);
         $generator->setRunScripts(!$input->getOption('no-scripts'));
         $generator->setIgnorePlatformRequirements($ignorePlatformReqs);
         $numberOfClasses = $generator->dump($config, $localRepo, $package, $installationManager, 'composer', $optimize);
diff --git a/src/Composer/Command/InstallCommand.php b/src/Composer/Command/InstallCommand.php
index cbcb0eae7..d3f450c50 100644
--- a/src/Composer/Command/InstallCommand.php
+++ b/src/Composer/Command/InstallCommand.php
@@ -49,7 +49,7 @@ class InstallCommand extends BaseCommand
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
                 new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
-                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache. Implicitly enables --apcu-autoloader'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
                 new InputArgument('packages', InputArgument::IS_ARRAY | InputArgument::OPTIONAL, 'Should not be provided, use composer require instead to add a given package to composer.json.'),
@@ -103,7 +103,8 @@ EOT
 
         $optimize = $input->getOption('optimize-autoloader') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = $input->getOption('apcu-autoloader') || $config->get('apcu-autoloader');
+        $apcuPrefix = $input->getOption('apcu-autoloader-prefix');
+        $apcu = $apcuPrefix !== null || $input->getOption('apcu-autoloader') || $config->get('apcu-autoloader');
 
         $ignorePlatformReqs = $input->getOption('ignore-platform-reqs') ?: ($input->getOption('ignore-platform-req') ?: false);
 
@@ -119,7 +120,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
+            ->setApcuAutoloader($apcu, $apcuPrefix)
             ->setIgnorePlatformRequirements($ignorePlatformReqs)
         ;
 
diff --git a/src/Composer/Command/RemoveCommand.php b/src/Composer/Command/RemoveCommand.php
index 8fb49e986..d9d6b17ce 100644
--- a/src/Composer/Command/RemoveCommand.php
+++ b/src/Composer/Command/RemoveCommand.php
@@ -55,7 +55,7 @@ class RemoveCommand extends BaseCommand
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
                 new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
-                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache. Implicitly enables --apcu-autoloader'),
             ))
             ->setHelp(
                 <<<EOT
@@ -228,7 +228,8 @@ EOT
         $updateDevMode = !$input->getOption('update-no-dev');
         $optimize = $input->getOption('optimize-autoloader') || $composer->getConfig()->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $composer->getConfig()->get('classmap-authoritative');
-        $apcu = $input->getOption('apcu-autoloader') || $composer->getConfig()->get('apcu-autoloader');
+        $apcuPrefix = $input->getOption('apcu-autoloader-prefix');
+        $apcu = $apcuPrefix !== null || $input->getOption('apcu-autoloader') || $composer->getConfig()->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_LISTED_WITH_TRANSITIVE_DEPS_NO_ROOT_REQUIRE;
         $flags = '';
@@ -249,7 +250,7 @@ EOT
             ->setDevMode($updateDevMode)
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
+            ->setApcuAutoloader($apcu, $apcuPrefix)
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateAllowList($packages)
diff --git a/src/Composer/Command/RequireCommand.php b/src/Composer/Command/RequireCommand.php
index f276b781c..4b286ae1e 100644
--- a/src/Composer/Command/RequireCommand.php
+++ b/src/Composer/Command/RequireCommand.php
@@ -77,7 +77,7 @@ class RequireCommand extends InitCommand
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
                 new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
-                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache. Implicitly enables --apcu-autoloader'),
             ))
             ->setHelp(
                 <<<EOT
@@ -270,7 +270,8 @@ EOT
         $updateDevMode = !$input->getOption('update-no-dev');
         $optimize = $input->getOption('optimize-autoloader') || $composer->getConfig()->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $composer->getConfig()->get('classmap-authoritative');
-        $apcu = $input->getOption('apcu-autoloader') || $composer->getConfig()->get('apcu-autoloader');
+        $apcuPrefix = $input->getOption('apcu-autoloader-prefix');
+        $apcu = $apcuPrefix !== null || $input->getOption('apcu-autoloader') || $composer->getConfig()->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_ONLY_LISTED;
         $flags = '';
@@ -302,7 +303,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
+            ->setApcuAutoloader($apcu, $apcuPrefix)
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateAllowTransitiveDependencies($updateAllowTransitiveDependencies)
diff --git a/src/Composer/Command/UpdateCommand.php b/src/Composer/Command/UpdateCommand.php
index cd404e95b..e716fa2f0 100644
--- a/src/Composer/Command/UpdateCommand.php
+++ b/src/Composer/Command/UpdateCommand.php
@@ -60,7 +60,7 @@ class UpdateCommand extends BaseCommand
                 new InputOption('optimize-autoloader', 'o', InputOption::VALUE_NONE, 'Optimize autoloader during autoloader dump.'),
                 new InputOption('classmap-authoritative', 'a', InputOption::VALUE_NONE, 'Autoload classes from the classmap only. Implicitly enables `--optimize-autoloader`.'),
                 new InputOption('apcu-autoloader', null, InputOption::VALUE_NONE, 'Use APCu to cache found/not-found classes.'),
-                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache'),
+                new InputOption('apcu-autoloader-prefix', null, InputOption::VALUE_REQUIRED, 'Use a custom prefix for the APCu autoloader cache. Implicitly enables --apcu-autoloader'),
                 new InputOption('ignore-platform-req', null, InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY, 'Ignore a specific platform requirement (php & ext- packages).'),
                 new InputOption('ignore-platform-reqs', null, InputOption::VALUE_NONE, 'Ignore all platform requirements (php & ext- packages).'),
                 new InputOption('prefer-stable', null, InputOption::VALUE_NONE, 'Prefer stable versions of dependencies.'),
@@ -190,7 +190,8 @@ EOT
 
         $optimize = $input->getOption('optimize-autoloader') || $config->get('optimize-autoloader');
         $authoritative = $input->getOption('classmap-authoritative') || $config->get('classmap-authoritative');
-        $apcu = $input->getOption('apcu-autoloader') || $config->get('apcu-autoloader');
+        $apcuPrefix = $input->getOption('apcu-autoloader-prefix');
+        $apcu = $apcuPrefix !== null || $input->getOption('apcu-autoloader') || $config->get('apcu-autoloader');
 
         $updateAllowTransitiveDependencies = Request::UPDATE_ONLY_LISTED;
         if ($input->getOption('with-all-dependencies')) {
@@ -211,7 +212,7 @@ EOT
             ->setRunScripts(!$input->getOption('no-scripts'))
             ->setOptimizeAutoloader($optimize)
             ->setClassMapAuthoritative($authoritative)
-            ->setApcuAutoloader($apcu, $input->getOption('apcu-autoloader-prefix'))
+            ->setApcuAutoloader($apcu, $apcuPrefix)
             ->setUpdate(true)
             ->setInstall(!$input->getOption('no-install'))
             ->setUpdateMirrors($updateMirrors)