From 00984f46f2b69dd85c1961bfa8f38bf7e7d8a0c8 Mon Sep 17 00:00:00 2001
From: Alexander Schranz <alexander@sulu.io>
Date: Fri, 18 Feb 2022 22:13:15 +0100
Subject: [PATCH 1/8] Add return types to closures

---
 src/Composer/Autoload/AutoloadGenerator.php   | 12 ++++----
 src/Composer/Command/ArchiveCommand.php       |  2 +-
 .../Command/BaseDependencyCommand.php         |  2 +-
 src/Composer/Command/ConfigCommand.php        | 28 +++++++++----------
 src/Composer/Command/DiagnoseCommand.php      |  2 +-
 src/Composer/Command/InitCommand.php          |  2 +-
 src/Composer/Command/LicensesCommand.php      |  2 +-
 src/Composer/Command/ReinstallCommand.php     |  2 +-
 src/Composer/Command/RemoveCommand.php        |  2 +-
 src/Composer/Command/SelfUpdateCommand.php    |  2 +-
 src/Composer/Command/ShowCommand.php          |  4 +--
 src/Composer/Command/StatusCommand.php        |  4 +--
 src/Composer/Command/UpdateCommand.php        |  4 +--
 src/Composer/Command/ValidateCommand.php      |  6 ++--
 src/Composer/Compiler.php                     |  2 +-
 src/Composer/Config/JsonConfigSource.php      | 18 ++++++------
 src/Composer/Console/Application.php          |  6 ++--
 .../DependencyResolver/DefaultPolicy.php      |  4 +--
 .../DependencyResolver/LockTransaction.php    |  2 +-
 .../DependencyResolver/PoolBuilder.php        |  2 +-
 src/Composer/DependencyResolver/Problem.php   |  8 +++---
 src/Composer/DependencyResolver/Rule.php      |  2 +-
 .../DependencyResolver/RuleWatchGraph.php     |  2 +-
 .../DependencyResolver/Transaction.php        |  6 ++--
 src/Composer/Downloader/ArchiveDownloader.php |  4 +--
 src/Composer/Downloader/DownloadManager.php   |  4 +--
 src/Composer/Downloader/FileDownloader.php    | 10 +++----
 src/Composer/Downloader/GitDownloader.php     |  6 ++--
 src/Composer/Downloader/HgDownloader.php      |  4 +--
 src/Composer/Downloader/SvnDownloader.php     |  2 +-
 src/Composer/Downloader/VcsDownloader.php     |  2 +-
 src/Composer/Downloader/ZipDownloader.php     |  2 +-
 src/Composer/IO/BufferIO.php                  |  2 +-
 src/Composer/IO/ConsoleIO.php                 |  2 +-
 src/Composer/Installer.php                    |  2 +-
 .../Installer/InstallationManager.php         | 18 ++++++------
 src/Composer/Installer/LibraryInstaller.php   |  8 +++---
 src/Composer/Installer/PluginInstaller.php    |  4 +--
 .../Installer/SuggestedPackagesReporter.php   |  2 +-
 src/Composer/Json/JsonManipulator.php         | 14 +++++-----
 .../Archiver/ArchivableFilesFinder.php        |  2 +-
 .../Package/Archiver/ArchiveManager.php       |  2 +-
 .../Package/Archiver/BaseExcludeFilter.php    |  2 +-
 src/Composer/Package/BasePackage.php          |  2 +-
 src/Composer/Package/Locker.php               |  2 +-
 .../Package/Version/VersionGuesser.php        |  2 +-
 .../Package/Version/VersionSelector.php       |  2 +-
 .../Question/StrictConfirmationQuestion.php   |  2 +-
 .../Repository/ComposerRepository.php         | 10 +++----
 .../Repository/CompositeRepository.php        |  2 +-
 .../Repository/FilesystemRepository.php       |  2 +-
 .../Repository/InstalledRepository.php        |  2 +-
 src/Composer/Repository/PathRepository.php    |  2 +-
 .../Repository/PlatformRepository.php         |  2 +-
 src/Composer/Repository/Vcs/GitDriver.php     |  2 +-
 src/Composer/Repository/Vcs/HgDriver.php      |  2 +-
 src/Composer/Util/AuthHelper.php              |  2 +-
 src/Composer/Util/ErrorHandler.php            |  2 +-
 src/Composer/Util/Git.php                     |  4 +--
 src/Composer/Util/HttpDownloader.php          |  8 +++---
 src/Composer/Util/Platform.php                |  2 +-
 src/Composer/Util/ProcessExecutor.php         |  8 +++---
 src/Composer/Util/RemoteFilesystem.php        |  4 +--
 src/Composer/Util/StreamContextFactory.php    |  2 +-
 src/Composer/Util/TlsHelper.php               |  6 ++--
 src/Composer/Util/Url.php                     |  2 +-
 66 files changed, 146 insertions(+), 146 deletions(-)

diff --git a/src/Composer/Autoload/AutoloadGenerator.php b/src/Composer/Autoload/AutoloadGenerator.php
index cbabb867bf99..d3560bfcf1b4 100644
--- a/src/Composer/Autoload/AutoloadGenerator.php
+++ b/src/Composer/Autoload/AutoloadGenerator.php
@@ -290,7 +290,7 @@ public function dump(Config $config, InstalledRepositoryInterface $localRepo, Ro
         $mainAutoload = $rootPackage->getAutoload();
         if ($rootPackage->getTargetDir() && !empty($mainAutoload['psr-0'])) {
             $levels = substr_count($filesystem->normalizePath($rootPackage->getTargetDir()), '/') + 1;
-            $prefixes = implode(', ', array_map(function ($prefix) {
+            $prefixes = implode(', ', array_map(function ($prefix): string {
                 return var_export($prefix, true);
             }, array_keys($mainAutoload['psr-0'])));
             $baseDirFromTargetDirCode = $filesystem->findShortestPathCode($targetDir, $basePath, true);
@@ -554,7 +554,7 @@ public function parseAutoloads(array $packageMap, PackageInterface $rootPackage,
     {
         $rootPackageMap = array_shift($packageMap);
         if (is_array($filteredDevPackages)) {
-            $packageMap = array_filter($packageMap, function ($item) use ($filteredDevPackages) {
+            $packageMap = array_filter($packageMap, function ($item) use ($filteredDevPackages): bool {
                 return !in_array($item[0]->getName(), $filteredDevPackages, true);
             });
         } elseif ($filteredDevPackages) {
@@ -808,7 +808,7 @@ protected function getPlatformCheck(array $packageMap, $checkPlatform, array $de
 
         ksort($requiredExtensions);
 
-        $formatToPhpVersionId = function (Bound $bound) {
+        $formatToPhpVersionId = function (Bound $bound): int {
             if ($bound->isZero()) {
                 return 0;
             }
@@ -1229,7 +1229,7 @@ protected function parseAutoloadsType(array $packageMap, $type, RootPackageInter
                         $updir = null;
                         $path = Preg::replaceCallback(
                             '{^((?:(?:\\\\\\.){1,2}+/)+)}',
-                            function ($matches) use (&$updir) {
+                            function ($matches) use (&$updir): string {
                                 if (isset($matches[1])) {
                                     // undo preg_quote for the matched string
                                     $updir = str_replace('\\.', '.', $matches[1]);
@@ -1300,7 +1300,7 @@ protected function filterPackageMap(array $packageMap, RootPackageInterface $roo
             }
         }
 
-        $add = function (PackageInterface $package) use (&$add, $packages, &$include, $replacedBy) {
+        $add = function (PackageInterface $package) use (&$add, $packages, &$include, $replacedBy): void {
             foreach ($package->getRequires() as $link) {
                 $target = $link->getTarget();
                 if (isset($replacedBy[$target])) {
@@ -1318,7 +1318,7 @@ protected function filterPackageMap(array $packageMap, RootPackageInterface $roo
 
         return array_filter(
             $packageMap,
-            function ($item) use ($include) {
+            function ($item) use ($include): bool {
                 $package = $item[0];
                 foreach ($package->getNames() as $name) {
                     if (isset($include[$name])) {
diff --git a/src/Composer/Command/ArchiveCommand.php b/src/Composer/Command/ArchiveCommand.php
index 314c0655443e..b785f4ea4fdc 100644
--- a/src/Composer/Command/ArchiveCommand.php
+++ b/src/Composer/Command/ArchiveCommand.php
@@ -168,7 +168,7 @@ protected function selectPackage(IOInterface $io, $packageName, $version = null)
         if (count($packages) > 1) {
             $package = reset($packages);
             $io->writeError('<info>Found multiple matches, selected '.$package->getPrettyString().'.</info>');
-            $io->writeError('Alternatives were '.implode(', ', array_map(function ($p) {
+            $io->writeError('Alternatives were '.implode(', ', array_map(function ($p): string {
                 return $p->getPrettyString();
             }, $packages)).'.');
             $io->writeError('<comment>Please use a more specific constraint to pick a different package.</comment>');
diff --git a/src/Composer/Command/BaseDependencyCommand.php b/src/Composer/Command/BaseDependencyCommand.php
index 11ee03556057..224d2739e9e6 100644
--- a/src/Composer/Command/BaseDependencyCommand.php
+++ b/src/Composer/Command/BaseDependencyCommand.php
@@ -90,7 +90,7 @@ protected function doExecute(InputInterface $input, OutputInterface $output, $in
         $needles = array($needle);
         if ($inverted) {
             foreach ($packages as $package) {
-                $needles = array_merge($needles, array_map(function (Link $link) {
+                $needles = array_merge($needles, array_map(function (Link $link): string {
                     return $link->getTarget();
                 }, $package->getReplaces()));
             }
diff --git a/src/Composer/Command/ConfigCommand.php b/src/Composer/Command/ConfigCommand.php
index 9071f3b926ac..3e51a45995b1 100644
--- a/src/Composer/Command/ConfigCommand.php
+++ b/src/Composer/Command/ConfigCommand.php
@@ -318,10 +318,10 @@ protected function execute(InputInterface $input, OutputInterface $output): int
 
         $values = $input->getArgument('setting-value'); // what the user is trying to add/change
 
-        $booleanValidator = function ($val) {
+        $booleanValidator = function ($val): bool {
             return in_array($val, array('true', 'false', '1', '0'), true);
         };
-        $booleanNormalizer = function ($val) {
+        $booleanNormalizer = function ($val): bool {
             return $val !== 'false' && (bool) $val;
         };
 
@@ -331,7 +331,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             'use-include-path' => array($booleanValidator, $booleanNormalizer),
             'use-github-api' => array($booleanValidator, $booleanNormalizer),
             'preferred-install' => array(
-                function ($val) {
+                function ($val): bool {
                     return in_array($val, array('auto', 'source', 'dist'), true);
                 },
                 function ($val) {
@@ -339,7 +339,7 @@ function ($val) {
                 },
             ),
             'gitlab-protocol' => array(
-                function ($val) {
+                function ($val): bool {
                     return in_array($val, array('git', 'http', 'https'), true);
                 },
                 function ($val) {
@@ -347,7 +347,7 @@ function ($val) {
                 },
             ),
             'store-auths' => array(
-                function ($val) {
+                function ($val): bool {
                     return in_array($val, array('true', 'false', 'prompt'), true);
                 },
                 function ($val) {
@@ -389,7 +389,7 @@ function ($val) {
             'cache-ttl' => array('is_numeric', 'intval'),
             'cache-files-ttl' => array('is_numeric', 'intval'),
             'cache-files-maxsize' => array(
-                function ($val) {
+                function ($val): bool {
                     return Preg::isMatch('/^\s*([0-9.]+)\s*(?:([kmg])(?:i?b)?)?\s*$/i', $val);
                 },
                 function ($val) {
@@ -397,7 +397,7 @@ function ($val) {
                 },
             ),
             'bin-compat' => array(
-                function ($val) {
+                function ($val): bool {
                     return in_array($val, array('auto', 'full', 'symlink'));
                 },
                 function ($val) {
@@ -405,7 +405,7 @@ function ($val) {
                 },
             ),
             'discard-changes' => array(
-                function ($val) {
+                function ($val): bool {
                     return in_array($val, array('stash', 'true', 'false', '1', '0'), true);
                 },
                 function ($val) {
@@ -427,7 +427,7 @@ function ($val) {
             'disable-tls' => array($booleanValidator, $booleanNormalizer),
             'secure-http' => array($booleanValidator, $booleanNormalizer),
             'cafile' => array(
-                function ($val) {
+                function ($val): bool {
                     return file_exists($val) && Filesystem::isReadable($val);
                 },
                 function ($val) {
@@ -435,7 +435,7 @@ function ($val) {
                 },
             ),
             'capath' => array(
-                function ($val) {
+                function ($val): bool {
                     return is_dir($val) && Filesystem::isReadable($val);
                 },
                 function ($val) {
@@ -447,7 +447,7 @@ function ($val) {
             'lock' => array($booleanValidator, $booleanNormalizer),
             'allow-plugins' => array($booleanValidator, $booleanNormalizer),
             'platform-check' => array(
-                function ($val) {
+                function ($val): bool {
                     return in_array($val, array('php-only', 'true', 'false', '1', '0'), true);
                 },
                 function ($val) {
@@ -459,7 +459,7 @@ function ($val) {
                 },
             ),
             'use-parent-dir' => array(
-                function ($val) {
+                function ($val): bool {
                     return in_array($val, array('true', 'false', 'prompt'), true);
                 },
                 function ($val) {
@@ -593,10 +593,10 @@ function ($vals) {
                 return $val;
             }),
             'minimum-stability' => array(
-                function ($val) {
+                function ($val): bool {
                     return isset(BasePackage::$stabilities[VersionParser::normalizeStability($val)]);
                 },
-                function ($val) {
+                function ($val): string {
                     return VersionParser::normalizeStability($val);
                 },
             ),
diff --git a/src/Composer/Command/DiagnoseCommand.php b/src/Composer/Command/DiagnoseCommand.php
index 9d231e2476e0..75bec936aeb0 100644
--- a/src/Composer/Command/DiagnoseCommand.php
+++ b/src/Composer/Command/DiagnoseCommand.php
@@ -511,7 +511,7 @@ private function outputResult($result): void
     private function checkPlatform()
     {
         $output = '';
-        $out = function ($msg, $style) use (&$output) {
+        $out = function ($msg, $style) use (&$output): void {
             $output .= '<'.$style.'>'.$msg.'</'.$style.'>'.PHP_EOL;
         };
 
diff --git a/src/Composer/Command/InitCommand.php b/src/Composer/Command/InitCommand.php
index 6a52fd2467b8..8b67c26abc1f 100644
--- a/src/Composer/Command/InitCommand.php
+++ b/src/Composer/Command/InitCommand.php
@@ -511,7 +511,7 @@ public function namespaceFromPackageName($packageName)
         }
 
         $namespace = array_map(
-            function ($part) {
+            function ($part): string {
                 $part = Preg::replace('/[^a-z0-9]/i', ' ', $part);
                 $part = ucwords($part);
 
diff --git a/src/Composer/Command/LicensesCommand.php b/src/Composer/Command/LicensesCommand.php
index f63eb53d1c73..f59034282a84 100644
--- a/src/Composer/Command/LicensesCommand.php
+++ b/src/Composer/Command/LicensesCommand.php
@@ -170,7 +170,7 @@ private function filterRequiredPackages(RepositoryInterface $repo, PackageInterf
         $packageListNames = array_keys($bucket);
         $packages = array_filter(
             $repo->getPackages(),
-            function ($package) use ($requires, $packageListNames) {
+            function ($package) use ($requires, $packageListNames): bool {
                 return in_array($package->getName(), $requires) && !in_array($package->getName(), $packageListNames);
             }
         );
diff --git a/src/Composer/Command/ReinstallCommand.php b/src/Composer/Command/ReinstallCommand.php
index 18c8e4560a2f..926ba983997c 100644
--- a/src/Composer/Command/ReinstallCommand.php
+++ b/src/Composer/Command/ReinstallCommand.php
@@ -123,7 +123,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
                 $installOrder[$op->getPackage()->getName()] = $index;
             }
         }
-        usort($uninstallOperations, function ($a, $b) use ($installOrder) {
+        usort($uninstallOperations, function ($a, $b) use ($installOrder): int {
             return $installOrder[$b->getPackage()->getName()] - $installOrder[$a->getPackage()->getName()];
         });
 
diff --git a/src/Composer/Command/RemoveCommand.php b/src/Composer/Command/RemoveCommand.php
index e33675224e7c..fdda37df1fc9 100644
--- a/src/Composer/Command/RemoveCommand.php
+++ b/src/Composer/Command/RemoveCommand.php
@@ -116,7 +116,7 @@ protected function interact(InputInterface $input, OutputInterface $output)
 
             if (count($input->getArgument('packages')) === 0) {
                 $this->getIO()->writeError('<info>No unused packages to remove</info>');
-                $this->setCode(function () {
+                $this->setCode(function (): int {
                     return 0;
                 });
             }
diff --git a/src/Composer/Command/SelfUpdateCommand.php b/src/Composer/Command/SelfUpdateCommand.php
index 5f78e3eb97f2..06b0d2d0d528 100644
--- a/src/Composer/Command/SelfUpdateCommand.php
+++ b/src/Composer/Command/SelfUpdateCommand.php
@@ -354,7 +354,7 @@ protected function fetchKeys(IOInterface $io, Config $config): void
 
         $io->write('Open <info>https://composer.github.io/pubkeys.html</info> to find the latest keys');
 
-        $validator = function ($value) {
+        $validator = function ($value): string {
             if (!Preg::isMatch('{^-----BEGIN PUBLIC KEY-----$}', trim($value))) {
                 throw new \UnexpectedValueException('Invalid input');
             }
diff --git a/src/Composer/Command/ShowCommand.php b/src/Composer/Command/ShowCommand.php
index ab886103122b..ae9350f1e2cb 100644
--- a/src/Composer/Command/ShowCommand.php
+++ b/src/Composer/Command/ShowCommand.php
@@ -223,7 +223,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
             if ($input->getOption('no-dev')) {
                 $packages = $this->filterRequiredPackages($installedRepo, $rootPkg);
-                $repos = $installedRepo = new InstalledRepository(array(new InstalledArrayRepository(array_map(function ($pkg) {
+                $repos = $installedRepo = new InstalledRepository(array(new InstalledArrayRepository(array_map(function ($pkg): \Composer\Package\PackageInterface {
                     return clone $pkg;
                 }, $packages))));
             }
@@ -320,7 +320,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
         if ($input->getOption('tree')) {
             $rootRequires = $this->getRootRequires();
             $packages = $installedRepo->getPackages();
-            usort($packages, function (BasePackage $a, BasePackage $b) {
+            usort($packages, function (BasePackage $a, BasePackage $b): int {
                 return strcmp((string) $a, (string) $b);
             });
             $arrayTree = array();
diff --git a/src/Composer/Command/StatusCommand.php b/src/Composer/Command/StatusCommand.php
index 4a7bfe2231d4..8aec0e70dcdb 100644
--- a/src/Composer/Command/StatusCommand.php
+++ b/src/Composer/Command/StatusCommand.php
@@ -163,7 +163,7 @@ private function doExecute(InputInterface $input): int
 
             foreach ($errors as $path => $changes) {
                 if ($input->getOption('verbose')) {
-                    $indentedChanges = implode("\n", array_map(function ($line) {
+                    $indentedChanges = implode("\n", array_map(function ($line): string {
                         return '    ' . ltrim($line);
                     }, explode("\n", $changes)));
                     $io->write('<info>'.$path.'</info>:');
@@ -179,7 +179,7 @@ private function doExecute(InputInterface $input): int
 
             foreach ($unpushedChanges as $path => $changes) {
                 if ($input->getOption('verbose')) {
-                    $indentedChanges = implode("\n", array_map(function ($line) {
+                    $indentedChanges = implode("\n", array_map(function ($line): string {
                         return '    ' . ltrim($line);
                     }, explode("\n", $changes)));
                     $io->write('<info>'.$path.'</info>:');
diff --git a/src/Composer/Command/UpdateCommand.php b/src/Composer/Command/UpdateCommand.php
index 119fab20e6ad..39decf7888e3 100644
--- a/src/Composer/Command/UpdateCommand.php
+++ b/src/Composer/Command/UpdateCommand.php
@@ -129,7 +129,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
         // extract --with shorthands from the allowlist
         if (count($packages) > 0) {
-            $allowlistPackagesWithRequirements = array_filter($packages, function ($pkg) {
+            $allowlistPackagesWithRequirements = array_filter($packages, function ($pkg): bool {
                 return Preg::isMatch('{\S+[ =:]\S+}', $pkg);
             });
             foreach ($this->formatRequirements($allowlistPackagesWithRequirements) as $package => $constraint) {
@@ -180,7 +180,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
 
         // the arguments lock/nothing/mirrors are not package names but trigger a mirror update instead
         // they are further mutually exclusive with listing actual package names
-        $filteredPackages = array_filter($packages, function ($package) {
+        $filteredPackages = array_filter($packages, function ($package): bool {
             return !in_array($package, array('lock', 'nothing', 'mirrors'), true);
         });
         $updateMirrors = $input->getOption('lock') || count($filteredPackages) != count($packages);
diff --git a/src/Composer/Command/ValidateCommand.php b/src/Composer/Command/ValidateCommand.php
index ee9ffa811f3c..8c5ad5aeab33 100644
--- a/src/Composer/Command/ValidateCommand.php
+++ b/src/Composer/Command/ValidateCommand.php
@@ -193,13 +193,13 @@ private function outputResult(IOInterface $io, $name, &$errors, &$warnings, $che
         }
 
         if ($errors) {
-            $errors = array_map(function ($err) {
+            $errors = array_map(function ($err): string {
                 return '- ' . $err;
             }, $errors);
             array_unshift($errors, '# General errors');
         }
         if ($warnings) {
-            $warnings = array_map(function ($err) {
+            $warnings = array_map(function ($err): string {
                 return '- ' . $err;
             }, $warnings);
             array_unshift($warnings, '# General warnings');
@@ -210,7 +210,7 @@ private function outputResult(IOInterface $io, $name, &$errors, &$warnings, $che
 
         // If checking publish errors, display them as errors, otherwise just show them as warnings
         if ($publishErrors) {
-            $publishErrors = array_map(function ($err) {
+            $publishErrors = array_map(function ($err): string {
                 return '- ' . $err;
             }, $publishErrors);
 
diff --git a/src/Composer/Compiler.php b/src/Composer/Compiler.php
index 6c30d2b6d7cc..6bf2504686a8 100644
--- a/src/Composer/Compiler.php
+++ b/src/Composer/Compiler.php
@@ -82,7 +82,7 @@ public function compile($pharFile = 'composer.phar'): void
 
         $phar->startBuffering();
 
-        $finderSort = function ($a, $b) {
+        $finderSort = function ($a, $b): int {
             return strcmp(strtr($a->getRealPath(), '\\', '/'), strtr($b->getRealPath(), '\\', '/'));
         };
 
diff --git a/src/Composer/Config/JsonConfigSource.php b/src/Composer/Config/JsonConfigSource.php
index 798e0af1c994..84de4f32c9fd 100644
--- a/src/Composer/Config/JsonConfigSource.php
+++ b/src/Composer/Config/JsonConfigSource.php
@@ -62,7 +62,7 @@ public function getName()
      */
     public function addRepository($name, $config, $append = true)
     {
-        $this->manipulateJson('addRepository', function (&$config, $repo, $repoConfig) use ($append) {
+        $this->manipulateJson('addRepository', function (&$config, $repo, $repoConfig) use ($append): void {
             // if converting from an array format to hashmap format, and there is a {"packagist.org":false} repo, we have
             // to convert it to "packagist.org": false key on the hashmap otherwise it fails schema validation
             if (isset($config['repositories'])) {
@@ -91,7 +91,7 @@ public function addRepository($name, $config, $append = true)
      */
     public function removeRepository($name)
     {
-        $this->manipulateJson('removeRepository', function (&$config, $repo) {
+        $this->manipulateJson('removeRepository', function (&$config, $repo): void {
             unset($config['repositories'][$repo]);
         }, $name);
     }
@@ -102,7 +102,7 @@ public function removeRepository($name)
     public function addConfigSetting($name, $value)
     {
         $authConfig = $this->authConfig;
-        $this->manipulateJson('addConfigSetting', function (&$config, $key, $val) use ($authConfig) {
+        $this->manipulateJson('addConfigSetting', function (&$config, $key, $val) use ($authConfig): void {
             if (Preg::isMatch('{^(bitbucket-oauth|github-oauth|gitlab-oauth|gitlab-token|bearer|http-basic|platform)\.}', $key)) {
                 list($key, $host) = explode('.', $key, 2);
                 if ($authConfig) {
@@ -122,7 +122,7 @@ public function addConfigSetting($name, $value)
     public function removeConfigSetting($name)
     {
         $authConfig = $this->authConfig;
-        $this->manipulateJson('removeConfigSetting', function (&$config, $key) use ($authConfig) {
+        $this->manipulateJson('removeConfigSetting', function (&$config, $key) use ($authConfig): void {
             if (Preg::isMatch('{^(bitbucket-oauth|github-oauth|gitlab-oauth|gitlab-token|bearer|http-basic|platform)\.}', $key)) {
                 list($key, $host) = explode('.', $key, 2);
                 if ($authConfig) {
@@ -141,7 +141,7 @@ public function removeConfigSetting($name)
      */
     public function addProperty($name, $value)
     {
-        $this->manipulateJson('addProperty', function (&$config, $key, $val) {
+        $this->manipulateJson('addProperty', function (&$config, $key, $val): void {
             if (strpos($key, 'extra.') === 0 || strpos($key, 'scripts.') === 0) {
                 $bits = explode('.', $key);
                 $last = array_pop($bits);
@@ -164,7 +164,7 @@ public function addProperty($name, $value)
      */
     public function removeProperty($name)
     {
-        $this->manipulateJson('removeProperty', function (&$config, $key) {
+        $this->manipulateJson('removeProperty', function (&$config, $key): void {
             if (strpos($key, 'extra.') === 0 || strpos($key, 'scripts.') === 0) {
                 $bits = explode('.', $key);
                 $last = array_pop($bits);
@@ -187,7 +187,7 @@ public function removeProperty($name)
      */
     public function addLink($type, $name, $value)
     {
-        $this->manipulateJson('addLink', function (&$config, $type, $name, $value) {
+        $this->manipulateJson('addLink', function (&$config, $type, $name, $value): void {
             $config[$type][$name] = $value;
         }, $type, $name, $value);
     }
@@ -197,10 +197,10 @@ public function addLink($type, $name, $value)
      */
     public function removeLink($type, $name)
     {
-        $this->manipulateJson('removeSubNode', function (&$config, $type, $name) {
+        $this->manipulateJson('removeSubNode', function (&$config, $type, $name): void {
             unset($config[$type][$name]);
         }, $type, $name);
-        $this->manipulateJson('removeMainKeyIfEmpty', function (&$config, $type) {
+        $this->manipulateJson('removeMainKeyIfEmpty', function (&$config, $type): void {
             if (0 === count($config[$type])) {
                 unset($config[$type]);
             }
diff --git a/src/Composer/Console/Application.php b/src/Composer/Console/Application.php
index 0d1b19ce1c2c..5bf8f6ffca9e 100644
--- a/src/Composer/Console/Application.php
+++ b/src/Composer/Console/Application.php
@@ -94,14 +94,14 @@ public function __construct()
         if (!$shutdownRegistered) {
             if (function_exists('pcntl_async_signals') && function_exists('pcntl_signal')) {
                 pcntl_async_signals(true);
-                pcntl_signal(SIGINT, function ($sig) {
+                pcntl_signal(SIGINT, function ($sig): void {
                     exit(130);
                 });
             }
 
             $shutdownRegistered = true;
 
-            register_shutdown_function(function () {
+            register_shutdown_function(function (): void {
                 $lastError = error_get_last();
 
                 if ($lastError && $lastError['message'] &&
@@ -291,7 +291,7 @@ function_exists('php_uname') ? php_uname('s') . ' / ' . php_uname('r') : 'Unknow
             }
 
             // Check system temp folder for usability as it can cause weird runtime issues otherwise
-            Silencer::call(function () use ($io) {
+            Silencer::call(function () use ($io): void {
                 $tempfile = sys_get_temp_dir() . '/temp-' . md5(microtime());
                 if (!(file_put_contents($tempfile, __FILE__) && (file_get_contents($tempfile) == __FILE__) && unlink($tempfile) && !file_exists($tempfile))) {
                     $io->writeError(sprintf('<error>PHP temp directory (%s) does not exist or is not writable to Composer. Set sys_temp_dir in your php.ini</error>', sys_get_temp_dir()));
diff --git a/src/Composer/DependencyResolver/DefaultPolicy.php b/src/Composer/DependencyResolver/DefaultPolicy.php
index c4e196f3791b..e9add445ffbd 100644
--- a/src/Composer/DependencyResolver/DefaultPolicy.php
+++ b/src/Composer/DependencyResolver/DefaultPolicy.php
@@ -66,7 +66,7 @@ public function selectPreferredPackages(Pool $pool, array $literals, $requiredPa
         $packages = $this->groupLiteralsByName($pool, $literals);
 
         foreach ($packages as &$nameLiterals) {
-            usort($nameLiterals, function ($a, $b) use ($pool, $requiredPackage) {
+            usort($nameLiterals, function ($a, $b) use ($pool, $requiredPackage): int {
                 return $this->compareByPriority($pool, $pool->literalToPackage($a), $pool->literalToPackage($b), $requiredPackage, true);
             });
         }
@@ -79,7 +79,7 @@ public function selectPreferredPackages(Pool $pool, array $literals, $requiredPa
         $selected = \call_user_func_array('array_merge', array_values($packages));
 
         // now sort the result across all packages to respect replaces across packages
-        usort($selected, function ($a, $b) use ($pool, $requiredPackage) {
+        usort($selected, function ($a, $b) use ($pool, $requiredPackage): int {
             return $this->compareByPriority($pool, $pool->literalToPackage($a), $pool->literalToPackage($b), $requiredPackage);
         });
 
diff --git a/src/Composer/DependencyResolver/LockTransaction.php b/src/Composer/DependencyResolver/LockTransaction.php
index 75da918aedbe..4d04a5cd680c 100644
--- a/src/Composer/DependencyResolver/LockTransaction.php
+++ b/src/Composer/DependencyResolver/LockTransaction.php
@@ -152,7 +152,7 @@ public function getAliases($aliases): array
             }
         }
 
-        usort($usedAliases, function ($a, $b) {
+        usort($usedAliases, function ($a, $b): int {
             return strcmp($a['package'], $b['package']);
         });
 
diff --git a/src/Composer/DependencyResolver/PoolBuilder.php b/src/Composer/DependencyResolver/PoolBuilder.php
index 8a3819203e7d..332914d32fd6 100644
--- a/src/Composer/DependencyResolver/PoolBuilder.php
+++ b/src/Composer/DependencyResolver/PoolBuilder.php
@@ -520,7 +520,7 @@ private function getSkippedRootRequires(Request $request, $name): array
         $matches = array();
 
         if (isset($rootRequires[$name])) {
-            return array_map(function (PackageInterface $package) use ($name) {
+            return array_map(function (PackageInterface $package) use ($name): string {
                 if ($name !== $package->getName()) {
                     return $package->getName() .' (via replace of '.$name.')';
                 }
diff --git a/src/Composer/DependencyResolver/Problem.php b/src/Composer/DependencyResolver/Problem.php
index a6e3249e1d1c..77e2975c87f0 100644
--- a/src/Composer/DependencyResolver/Problem.php
+++ b/src/Composer/DependencyResolver/Problem.php
@@ -286,7 +286,7 @@ public static function getMissingPackageReason(RepositorySet $repositorySet, Req
         if ($packages = $repositorySet->findPackages($packageName, $constraint)) {
             $rootReqs = $repositorySet->getRootRequires();
             if (isset($rootReqs[$packageName])) {
-                $filtered = array_filter($packages, function ($p) use ($rootReqs, $packageName) {
+                $filtered = array_filter($packages, function ($p) use ($rootReqs, $packageName): bool {
                     return $rootReqs[$packageName]->matches(new Constraint('==', $p->getVersion()));
                 });
                 if (0 === count($filtered)) {
@@ -296,7 +296,7 @@ public static function getMissingPackageReason(RepositorySet $repositorySet, Req
 
             if ($lockedPackage) {
                 $fixedConstraint = new Constraint('==', $lockedPackage->getVersion());
-                $filtered = array_filter($packages, function ($p) use ($fixedConstraint) {
+                $filtered = array_filter($packages, function ($p) use ($fixedConstraint): bool {
                     return $fixedConstraint->matches(new Constraint('==', $p->getVersion()));
                 });
                 if (0 === count($filtered)) {
@@ -304,7 +304,7 @@ public static function getMissingPackageReason(RepositorySet $repositorySet, Req
                 }
             }
 
-            $nonLockedPackages = array_filter($packages, function ($p) {
+            $nonLockedPackages = array_filter($packages, function ($p): bool {
                 return !$p->getRepository() instanceof LockArrayRepository;
             });
 
@@ -360,7 +360,7 @@ public static function getMissingPackageReason(RepositorySet $repositorySet, Req
 
         if ($providers = $repositorySet->getProviders($packageName)) {
             $maxProviders = 20;
-            $providersStr = implode(array_map(function ($p) {
+            $providersStr = implode(array_map(function ($p): string {
                 $description = $p['description'] ? ' '.substr($p['description'], 0, 100) : '';
 
                 return "      - ${p['name']}".$description."\n";
diff --git a/src/Composer/DependencyResolver/Rule.php b/src/Composer/DependencyResolver/Rule.php
index d6863c461136..1e2d08daa949 100644
--- a/src/Composer/DependencyResolver/Rule.php
+++ b/src/Composer/DependencyResolver/Rule.php
@@ -281,7 +281,7 @@ public function getPrettyString(RepositorySet $repositorySet, Request $request,
                     return 'No package found to satisfy root composer.json require '.$packageName.($constraint ? ' '.$constraint->getPrettyString() : '');
                 }
 
-                $packagesNonAlias = array_values(array_filter($packages, function ($p) {
+                $packagesNonAlias = array_values(array_filter($packages, function ($p): bool {
                     return !($p instanceof AliasPackage);
                 }));
                 if (count($packagesNonAlias) === 1) {
diff --git a/src/Composer/DependencyResolver/RuleWatchGraph.php b/src/Composer/DependencyResolver/RuleWatchGraph.php
index 089367803b5d..03da05ce256e 100644
--- a/src/Composer/DependencyResolver/RuleWatchGraph.php
+++ b/src/Composer/DependencyResolver/RuleWatchGraph.php
@@ -110,7 +110,7 @@ public function propagateLiteral($decidedLiteral, $level, Decisions $decisions):
                 if (!$node->getRule()->isDisabled() && !$decisions->satisfy($otherWatch)) {
                     $ruleLiterals = $node->getRule()->getLiterals();
 
-                    $alternativeLiterals = array_filter($ruleLiterals, function ($ruleLiteral) use ($literal, $otherWatch, $decisions) {
+                    $alternativeLiterals = array_filter($ruleLiterals, function ($ruleLiteral) use ($literal, $otherWatch, $decisions): bool {
                         return $literal !== $ruleLiteral &&
                             $otherWatch !== $ruleLiteral &&
                             !$decisions->conflict($ruleLiteral);
diff --git a/src/Composer/DependencyResolver/Transaction.php b/src/Composer/DependencyResolver/Transaction.php
index 2e6640eeeae5..2d3272c51a59 100644
--- a/src/Composer/DependencyResolver/Transaction.php
+++ b/src/Composer/DependencyResolver/Transaction.php
@@ -71,7 +71,7 @@ public function getOperations(): array
      */
     private function setResultPackageMaps($resultPackages): void
     {
-        $packageSort = function (PackageInterface $a, PackageInterface $b) {
+        $packageSort = function (PackageInterface $a, PackageInterface $b): int {
             // sort alias packages by the same name behind their non alias version
             if ($a->getName() == $b->getName()) {
                 if ($a instanceof AliasPackage != $b instanceof AliasPackage) {
@@ -289,7 +289,7 @@ private function movePluginsToFront(array $operations): array
             // is this a downloads modifying plugin or a dependency of one?
             if ($isDownloadsModifyingPlugin || count(array_intersect($package->getNames(), $dlModifyingPluginRequires))) {
                 // get the package's requires, but filter out any platform requirements
-                $requires = array_filter(array_keys($package->getRequires()), function ($req) {
+                $requires = array_filter(array_keys($package->getRequires()), function ($req): bool {
                     return !PlatformRepository::isPlatformPackage($req);
                 });
 
@@ -314,7 +314,7 @@ private function movePluginsToFront(array $operations): array
             // is this a plugin or a dependency of a plugin?
             if ($isPlugin || count(array_intersect($package->getNames(), $pluginRequires))) {
                 // get the package's requires, but filter out any platform requirements
-                $requires = array_filter(array_keys($package->getRequires()), function ($req) {
+                $requires = array_filter(array_keys($package->getRequires()), function ($req): bool {
                     return !PlatformRepository::isPlatformPackage($req);
                 });
 
diff --git a/src/Composer/Downloader/ArchiveDownloader.php b/src/Composer/Downloader/ArchiveDownloader.php
index ddbea79c05bd..152dfb9c4ff5 100644
--- a/src/Composer/Downloader/ArchiveDownloader.php
+++ b/src/Composer/Downloader/ArchiveDownloader.php
@@ -116,7 +116,7 @@ public function install(PackageInterface $package, $path, $output = true)
             $promise = \React\Promise\resolve();
         }
 
-        return $promise->then(function () use ($package, $filesystem, $fileName, $temporaryDir, $path) {
+        return $promise->then(function () use ($package, $filesystem, $fileName, $temporaryDir, $path): \React\Promise\PromiseInterface {
             $filesystem->unlink($fileName);
 
             /**
@@ -125,7 +125,7 @@ public function install(PackageInterface $package, $path, $output = true)
              * @param  string         $dir Directory
              * @return \SplFileInfo[]
              */
-            $getFolderContent = function ($dir) {
+            $getFolderContent = function ($dir): array {
                 $finder = Finder::create()
                     ->ignoreVCS(false)
                     ->ignoreDotFiles(false)
diff --git a/src/Composer/Downloader/DownloadManager.php b/src/Composer/Downloader/DownloadManager.php
index 55f80208e272..0a7d6c9abc2e 100644
--- a/src/Composer/Downloader/DownloadManager.php
+++ b/src/Composer/Downloader/DownloadManager.php
@@ -331,7 +331,7 @@ public function update(PackageInterface $initial, PackageInterface $target, $tar
         // we wipe the dir and do a new install instead of updating it
         $promise = $initialDownloader->remove($initial, $targetDir);
         if ($promise) {
-            return $promise->then(function ($res) use ($target, $targetDir) {
+            return $promise->then(function ($res) use ($target, $targetDir): ?\React\Promise\PromiseInterface {
                 return $this->install($target, $targetDir);
             });
         }
@@ -432,7 +432,7 @@ private function getAvailableSources(PackageInterface $package, PackageInterface
             && !(!$prevPackage->isDev() && $prevPackage->getInstallationSource() === 'dist' && $package->isDev())
         ) {
             $prevSource = $prevPackage->getInstallationSource();
-            usort($sources, function ($a, $b) use ($prevSource) {
+            usort($sources, function ($a, $b) use ($prevSource): int {
                 return $a === $prevSource ? -1 : 1;
             });
 
diff --git a/src/Composer/Downloader/FileDownloader.php b/src/Composer/Downloader/FileDownloader.php
index f4bd777dfe77..5b184ec30ffc 100644
--- a/src/Composer/Downloader/FileDownloader.php
+++ b/src/Composer/Downloader/FileDownloader.php
@@ -118,7 +118,7 @@ public function download(PackageInterface $package, $path, PackageInterface $pre
             throw new \InvalidArgumentException('The given package is missing url information');
         }
 
-        $cacheKeyGenerator = function (PackageInterface $package, $key) {
+        $cacheKeyGenerator = function (PackageInterface $package, $key): string {
             $cacheKey = sha1($key);
 
             return $package->getName().'/'.$cacheKey.'.'.$package->getDistType();
@@ -195,7 +195,7 @@ public function download(PackageInterface $package, $path, PackageInterface $pre
                     ->then($accept, $reject);
             }
 
-            return $result->then(function ($result) use ($fileName, $checksum, $url, $package, $eventDispatcher) {
+            return $result->then(function ($result) use ($fileName, $checksum, $url, $package, $eventDispatcher): string {
                 // in case of retry, the first call's Promise chain finally calls this twice at the end,
                 // once with $result being the returned $fileName from $accept, and then once for every
                 // failed request with a null result, which can be skipped.
@@ -221,7 +221,7 @@ public function download(PackageInterface $package, $path, PackageInterface $pre
             });
         };
 
-        $accept = function ($response) use ($cache, $package, $fileName, &$urls) {
+        $accept = function ($response) use ($cache, $package, $fileName, &$urls): string {
             $url = reset($urls);
             $cacheKey = $url['cacheKey'];
             FileDownloader::$downloadMetadata[$package->getName()] = @filesize($fileName) ?: $response->getHeader('Content-Length') ?: '?';
@@ -407,7 +407,7 @@ public function update(PackageInterface $initial, PackageInterface $target, $pat
             $promise = \React\Promise\resolve();
         }
 
-        return $promise->then(function () use ($target, $path) {
+        return $promise->then(function () use ($target, $path): ?\React\Promise\PromiseInterface {
             $promise = $this->install($target, $path, false);
 
             return $promise;
@@ -426,7 +426,7 @@ public function remove(PackageInterface $package, $path, $output = true)
         }
         $promise = $this->filesystem->removeDirectoryAsync($path);
 
-        return $promise->then(function ($result) use ($path) {
+        return $promise->then(function ($result) use ($path): void {
             if (!$result) {
                 throw new \RuntimeException('Could not completely delete '.$path.', aborting.');
             }
diff --git a/src/Composer/Downloader/GitDownloader.php b/src/Composer/Downloader/GitDownloader.php
index 33ff7922a839..7f7d74c9f275 100644
--- a/src/Composer/Downloader/GitDownloader.php
+++ b/src/Composer/Downloader/GitDownloader.php
@@ -114,7 +114,7 @@ protected function doInstall(PackageInterface $package, $path, $url)
 
         $this->io->writeError($msg);
 
-        $commandCallable = function ($url) use ($path, $command, $cachePath) {
+        $commandCallable = function ($url) use ($path, $command, $cachePath): string {
             return str_replace(
                 array('%url%', '%path%', '%cachePath%', '%sanitizedUrl%'),
                 array(
@@ -172,7 +172,7 @@ protected function doUpdate(PackageInterface $initial, PackageInterface $target,
 
         $this->io->writeError($msg);
 
-        $commandCallable = function ($url) use ($ref, $command, $cachePath) {
+        $commandCallable = function ($url) use ($ref, $command, $cachePath): string {
             return str_replace(
                 array('%url%', '%ref%', '%cachePath%', '%sanitizedUrl%'),
                 array(
@@ -358,7 +358,7 @@ protected function cleanChanges(PackageInterface $package, $path, $update)
             return parent::cleanChanges($package, $path, $update);
         }
 
-        $changes = array_map(function ($elem) {
+        $changes = array_map(function ($elem): string {
             return '    '.$elem;
         }, Preg::split('{\s*\r?\n\s*}', $changes));
         $this->io->writeError('    <error>'.$package->getPrettyName().' has modified files:</error>');
diff --git a/src/Composer/Downloader/HgDownloader.php b/src/Composer/Downloader/HgDownloader.php
index 41dfb3e3b903..d7db15a230f1 100644
--- a/src/Composer/Downloader/HgDownloader.php
+++ b/src/Composer/Downloader/HgDownloader.php
@@ -41,7 +41,7 @@ protected function doInstall(PackageInterface $package, $path, $url): ?PromiseIn
     {
         $hgUtils = new HgUtils($this->io, $this->config, $this->process);
 
-        $cloneCommand = function ($url) use ($path) {
+        $cloneCommand = function ($url) use ($path): string {
             return sprintf('hg clone -- %s %s', ProcessExecutor::escape($url), ProcessExecutor::escape($path));
         };
 
@@ -70,7 +70,7 @@ protected function doUpdate(PackageInterface $initial, PackageInterface $target,
             throw new \RuntimeException('The .hg directory is missing from '.$path.', see https://getcomposer.org/commit-deps for more information');
         }
 
-        $command = function ($url) use ($ref) {
+        $command = function ($url) use ($ref): string {
             return sprintf('hg pull -- %s && hg up -- %s', ProcessExecutor::escape($url), ProcessExecutor::escape($ref));
         };
 
diff --git a/src/Composer/Downloader/SvnDownloader.php b/src/Composer/Downloader/SvnDownloader.php
index 0d269121c9e0..7dd58493ed8a 100644
--- a/src/Composer/Downloader/SvnDownloader.php
+++ b/src/Composer/Downloader/SvnDownloader.php
@@ -144,7 +144,7 @@ protected function cleanChanges(PackageInterface $package, $path, $update)
             return parent::cleanChanges($package, $path, $update);
         }
 
-        $changes = array_map(function ($elem) {
+        $changes = array_map(function ($elem): string {
             return '    '.$elem;
         }, Preg::split('{\s*\r?\n\s*}', $changes));
         $countChanges = count($changes);
diff --git a/src/Composer/Downloader/VcsDownloader.php b/src/Composer/Downloader/VcsDownloader.php
index b87deb044cc4..836925b66246 100644
--- a/src/Composer/Downloader/VcsDownloader.php
+++ b/src/Composer/Downloader/VcsDownloader.php
@@ -200,7 +200,7 @@ public function update(PackageInterface $initial, PackageInterface $target, $pat
             }
 
             if (trim($logs)) {
-                $logs = implode("\n", array_map(function ($line) {
+                $logs = implode("\n", array_map(function ($line): string {
                     return '      ' . $line;
                 }, explode("\n", $logs)));
 
diff --git a/src/Composer/Downloader/ZipDownloader.php b/src/Composer/Downloader/ZipDownloader.php
index 1347f296d85f..a1f297a9d3b9 100644
--- a/src/Composer/Downloader/ZipDownloader.php
+++ b/src/Composer/Downloader/ZipDownloader.php
@@ -127,7 +127,7 @@ private function extractWithSystemUnzip(PackageInterface $package, $file, $path)
         $executable = $commandSpec[0];
 
         $io = $this->io;
-        $tryFallback = function ($processError) use ($isLastChance, $io, $file, $path, $package, $executable) {
+        $tryFallback = function ($processError) use ($isLastChance, $io, $file, $path, $package, $executable): \React\Promise\PromiseInterface {
             if ($isLastChance) {
                 throw $processError;
             }
diff --git a/src/Composer/IO/BufferIO.php b/src/Composer/IO/BufferIO.php
index 3adfb900e72d..4d7242120fcb 100644
--- a/src/Composer/IO/BufferIO.php
+++ b/src/Composer/IO/BufferIO.php
@@ -56,7 +56,7 @@ public function getOutput(): string
 
         $output = stream_get_contents($this->output->getStream());
 
-        $output = Preg::replaceCallback("{(?<=^|\n|\x08)(.+?)(\x08+)}", function ($matches) {
+        $output = Preg::replaceCallback("{(?<=^|\n|\x08)(.+?)(\x08+)}", function ($matches): string {
             $pre = strip_tags($matches[1]);
 
             if (strlen($pre) === strlen($matches[2])) {
diff --git a/src/Composer/IO/ConsoleIO.php b/src/Composer/IO/ConsoleIO.php
index b4e19846f39a..2fd2cb178e97 100644
--- a/src/Composer/IO/ConsoleIO.php
+++ b/src/Composer/IO/ConsoleIO.php
@@ -175,7 +175,7 @@ private function doWrite($messages, $newline, $stderr, $verbosity, $raw = false)
         if (null !== $this->startTime) {
             $memoryUsage = memory_get_usage() / 1024 / 1024;
             $timeSpent = microtime(true) - $this->startTime;
-            $messages = array_map(function ($message) use ($memoryUsage, $timeSpent) {
+            $messages = array_map(function ($message) use ($memoryUsage, $timeSpent): string {
                 return sprintf('[%.1fMiB/%.2fs] %s', $memoryUsage, $timeSpent, $message);
             }, (array) $messages);
         }
diff --git a/src/Composer/Installer.php b/src/Composer/Installer.php
index d52e450dd358..18b798d7b923 100644
--- a/src/Composer/Installer.php
+++ b/src/Composer/Installer.php
@@ -522,7 +522,7 @@ protected function doUpdate(InstalledRepositoryInterface $localRepo, $doInstall)
             }
         }
 
-        $sortByName = function ($a, $b) {
+        $sortByName = function ($a, $b): int {
             if ($a instanceof UpdateOperation) {
                 $a = $a->getTargetPackage()->getName();
             } else {
diff --git a/src/Composer/Installer/InstallationManager.php b/src/Composer/Installer/InstallationManager.php
index cb3aafbd83e1..8102e4537a6d 100644
--- a/src/Composer/Installer/InstallationManager.php
+++ b/src/Composer/Installer/InstallationManager.php
@@ -199,18 +199,18 @@ public function execute(InstalledRepositoryInterface $repo, array $operations, $
 
         $loop = $this->loop;
         $io = $this->io;
-        $runCleanup = function () use (&$cleanupPromises, $loop) {
+        $runCleanup = function () use (&$cleanupPromises, $loop): void {
             $promises = array();
 
             $loop->abortJobs();
 
             foreach ($cleanupPromises as $cleanup) {
-                $promises[] = new \React\Promise\Promise(function ($resolve, $reject) use ($cleanup) {
+                $promises[] = new \React\Promise\Promise(function ($resolve, $reject) use ($cleanup): void {
                     $promise = $cleanup();
                     if (!$promise instanceof PromiseInterface) {
                         $resolve();
                     } else {
-                        $promise->then(function () use ($resolve) {
+                        $promise->then(function () use ($resolve): void {
                             $resolve();
                         });
                     }
@@ -229,7 +229,7 @@ public function execute(InstalledRepositoryInterface $repo, array $operations, $
         if ($handleInterruptsUnix) {
             pcntl_async_signals(true);
             $prevHandler = pcntl_signal_get_handler(SIGINT);
-            pcntl_signal(SIGINT, function ($sig) use ($runCleanup, $prevHandler, $io) {
+            pcntl_signal(SIGINT, function ($sig) use ($runCleanup, $prevHandler, $io): void {
                 $io->writeError('Received SIGINT, aborting', true, IOInterface::DEBUG);
                 $runCleanup();
 
@@ -241,7 +241,7 @@ public function execute(InstalledRepositoryInterface $repo, array $operations, $
             });
         }
         if ($handleInterruptsWindows) {
-            $windowsHandler = function ($event) use ($runCleanup, $io) {
+            $windowsHandler = function ($event) use ($runCleanup, $io): void {
                 if ($event !== PHP_WINDOWS_EVENT_CTRL_C) {
                     return;
                 }
@@ -446,15 +446,15 @@ private function executeBatch(InstalledRepositoryInterface $repo, array $operati
             $promise = $promise->then(function () use ($opType, $repo, $operation) {
                 return $this->$opType($repo, $operation);
             })->then($cleanupPromises[$index])
-            ->then(function () use ($devMode, $repo) {
+            ->then(function () use ($devMode, $repo): void {
                 $repo->write($devMode, $this);
-            }, function ($e) use ($opType, $package, $io) {
+            }, function ($e) use ($opType, $package, $io): void {
                 $io->writeError('    <error>' . ucfirst($opType) .' of '.$package->getPrettyName().' failed</error>');
 
                 throw $e;
             });
 
-            $postExecCallbacks[] = function () use ($opType, $runScripts, $dispatcher, $devMode, $repo, $allOperations, $operation) {
+            $postExecCallbacks[] = function () use ($opType, $runScripts, $dispatcher, $devMode, $repo, $allOperations, $operation): void {
                 $event = 'Composer\Installer\PackageEvents::POST_PACKAGE_'.strtoupper($opType);
                 if (defined($event) && $runScripts && $dispatcher) {
                     $dispatcher->dispatchPackageEvent(constant($event), $devMode, $repo, $allOperations, $operation);
@@ -548,7 +548,7 @@ public function update(InstalledRepositoryInterface $repo, UpdateOperation $oper
             }
 
             $installer = $this->getInstaller($targetType);
-            $promise = $promise->then(function () use ($installer, $repo, $target) {
+            $promise = $promise->then(function () use ($installer, $repo, $target): ?\React\Promise\PromiseInterface {
                 return $installer->install($repo, $target);
             });
         }
diff --git a/src/Composer/Installer/LibraryInstaller.php b/src/Composer/Installer/LibraryInstaller.php
index 8fff84d46556..484daf8c837c 100644
--- a/src/Composer/Installer/LibraryInstaller.php
+++ b/src/Composer/Installer/LibraryInstaller.php
@@ -148,7 +148,7 @@ public function install(InstalledRepositoryInterface $repo, PackageInterface $pa
         $binaryInstaller = $this->binaryInstaller;
         $installPath = $this->getInstallPath($package);
 
-        return $promise->then(function () use ($binaryInstaller, $installPath, $package, $repo) {
+        return $promise->then(function () use ($binaryInstaller, $installPath, $package, $repo): void {
             $binaryInstaller->installBinaries($package, $installPath);
             if (!$repo->hasPackage($package)) {
                 $repo->addPackage(clone $package);
@@ -176,7 +176,7 @@ public function update(InstalledRepositoryInterface $repo, PackageInterface $ini
         $binaryInstaller = $this->binaryInstaller;
         $installPath = $this->getInstallPath($target);
 
-        return $promise->then(function () use ($binaryInstaller, $installPath, $target, $initial, $repo) {
+        return $promise->then(function () use ($binaryInstaller, $installPath, $target, $initial, $repo): void {
             $binaryInstaller->installBinaries($target, $installPath);
             $repo->removePackage($initial);
             if (!$repo->hasPackage($target)) {
@@ -203,7 +203,7 @@ public function uninstall(InstalledRepositoryInterface $repo, PackageInterface $
         $downloadPath = $this->getPackageBasePath($package);
         $filesystem = $this->filesystem;
 
-        return $promise->then(function () use ($binaryInstaller, $filesystem, $downloadPath, $package, $repo) {
+        return $promise->then(function () use ($binaryInstaller, $filesystem, $downloadPath, $package, $repo): void {
             $binaryInstaller->removeBinaries($package);
             $repo->removePackage($package);
 
@@ -288,7 +288,7 @@ protected function updateCode(PackageInterface $initial, PackageInterface $targe
                     $promise = \React\Promise\resolve();
                 }
 
-                return $promise->then(function () use ($target) {
+                return $promise->then(function () use ($target): ?\React\Promise\PromiseInterface {
                     return $this->installCode($target);
                 });
             }
diff --git a/src/Composer/Installer/PluginInstaller.php b/src/Composer/Installer/PluginInstaller.php
index ce4c75933f08..2dded4eac6cc 100644
--- a/src/Composer/Installer/PluginInstaller.php
+++ b/src/Composer/Installer/PluginInstaller.php
@@ -66,7 +66,7 @@ public function install(InstalledRepositoryInterface $repo, PackageInterface $pa
             $promise = \React\Promise\resolve();
         }
 
-        return $promise->then(function () use ($package, $repo) {
+        return $promise->then(function () use ($package, $repo): void {
             try {
                 Platform::workaroundFilesystemIssues();
                 $this->getPluginManager()->registerPackage($package, true);
@@ -86,7 +86,7 @@ public function update(InstalledRepositoryInterface $repo, PackageInterface $ini
             $promise = \React\Promise\resolve();
         }
 
-        return $promise->then(function () use ($initial, $target, $repo) {
+        return $promise->then(function () use ($initial, $target, $repo): void {
             try {
                 Platform::workaroundFilesystemIssues();
                 $this->getPluginManager()->deactivatePackage($initial);
diff --git a/src/Composer/Installer/SuggestedPackagesReporter.php b/src/Composer/Installer/SuggestedPackagesReporter.php
index e337c43ae9b6..17e51b5f6567 100644
--- a/src/Composer/Installer/SuggestedPackagesReporter.php
+++ b/src/Composer/Installer/SuggestedPackagesReporter.php
@@ -198,7 +198,7 @@ private function getFilteredSuggestions(InstalledRepository $installedRepo = nul
 
         $sourceFilter = array();
         if ($onlyDependentsOf) {
-            $sourceFilter = array_map(function ($link) {
+            $sourceFilter = array_map(function ($link): string {
                 return $link->getTarget();
             }, array_merge($onlyDependentsOf->getRequires(), $onlyDependentsOf->getDevRequires()));
             $sourceFilter[] = $onlyDependentsOf->getName();
diff --git a/src/Composer/Json/JsonManipulator.php b/src/Composer/Json/JsonManipulator.php
index 60cbef0c1c2e..8a309086d6de 100644
--- a/src/Composer/Json/JsonManipulator.php
+++ b/src/Composer/Json/JsonManipulator.php
@@ -94,7 +94,7 @@ public function addLink($type, $package, $constraint, $sortPackages = false)
             // update existing link
             $existingPackage = $packageMatches['package'];
             $packageRegex = str_replace('/', '\\\\?/', preg_quote($existingPackage));
-            $links = Preg::replaceCallback('{'.self::$DEFINES.'"'.$packageRegex.'"(?P<separator>\s*:\s*)(?&string)}ix', function ($m) use ($existingPackage, $constraint) {
+            $links = Preg::replaceCallback('{'.self::$DEFINES.'"'.$packageRegex.'"(?P<separator>\s*:\s*)(?&string)}ix', function ($m) use ($existingPackage, $constraint): string {
                 return JsonFile::encode(str_replace('\\/', '/', $existingPackage)) . $m['separator'] . '"' . $constraint . '"';
             }, $links);
         } else {
@@ -135,7 +135,7 @@ public function addLink($type, $package, $constraint, $sortPackages = false)
      */
     private function sortPackages(array &$packages = array()): void
     {
-        $prefix = function ($requirement) {
+        $prefix = function ($requirement): string {
             if (PlatformRepository::isPlatformPackage($requirement)) {
                 return Preg::replace(
                     array(
@@ -159,7 +159,7 @@ private function sortPackages(array &$packages = array()): void
             return '5-'.$requirement;
         };
 
-        uksort($packages, function ($a, $b) use ($prefix) {
+        uksort($packages, function ($a, $b) use ($prefix): int {
             return strnatcmp($prefix($a), $prefix($b));
         });
     }
@@ -297,7 +297,7 @@ public function addSubNode($mainNode, $name, $value, $append = true)
         // child exists
         $childRegex = '{'.self::$DEFINES.'(?P<start>"'.preg_quote($name).'"\s*:\s*)(?P<content>(?&json))(?P<end>,?)}x';
         if (Preg::isMatch($childRegex, $children, $matches)) {
-            $children = Preg::replaceCallback($childRegex, function ($matches) use ($subName, $value) {
+            $children = Preg::replaceCallback($childRegex, function ($matches) use ($subName, $value): string {
                 if ($subName !== null) {
                     $curVal = json_decode($matches['content'], true);
                     if (!is_array($curVal)) {
@@ -351,7 +351,7 @@ public function addSubNode($mainNode, $name, $value, $append = true)
             }
         }
 
-        $this->contents = Preg::replaceCallback($nodeRegex, function ($m) use ($children) {
+        $this->contents = Preg::replaceCallback($nodeRegex, function ($m) use ($children): string {
             return $m['start'] . $children . $m['end'];
         }, $this->contents);
 
@@ -436,7 +436,7 @@ public function removeSubNode($mainNode, $name)
             $newline = $this->newline;
             $indent = $this->indent;
 
-            $this->contents = Preg::replaceCallback($nodeRegex, function ($matches) use ($indent, $newline) {
+            $this->contents = Preg::replaceCallback($nodeRegex, function ($matches) use ($indent, $newline): string {
                 return $matches['start'] . '{' . $newline . $indent . '}' . $matches['end'];
             }, $this->contents);
 
@@ -450,7 +450,7 @@ public function removeSubNode($mainNode, $name)
             return true;
         }
 
-        $this->contents = Preg::replaceCallback($nodeRegex, function ($matches) use ($name, $subName, $childrenClean) {
+        $this->contents = Preg::replaceCallback($nodeRegex, function ($matches) use ($name, $subName, $childrenClean): string {
             if ($subName !== null) {
                 $curVal = json_decode($matches['content'], true);
                 unset($curVal[$name][$subName]);
diff --git a/src/Composer/Package/Archiver/ArchivableFilesFinder.php b/src/Composer/Package/Archiver/ArchivableFilesFinder.php
index b1d5650ed916..31e81e295fa8 100644
--- a/src/Composer/Package/Archiver/ArchivableFilesFinder.php
+++ b/src/Composer/Package/Archiver/ArchivableFilesFinder.php
@@ -57,7 +57,7 @@ public function __construct($sources, array $excludes, $ignoreFilters = false)
 
         $this->finder = new Finder();
 
-        $filter = function (\SplFileInfo $file) use ($sources, $filters, $fs) {
+        $filter = function (\SplFileInfo $file) use ($sources, $filters, $fs): bool {
             if ($file->isLink() && strpos($file->getRealPath(), $sources) !== 0) {
                 return false;
             }
diff --git a/src/Composer/Package/Archiver/ArchiveManager.php b/src/Composer/Package/Archiver/ArchiveManager.php
index aed992ef49d3..de8ff52e8a67 100644
--- a/src/Composer/Package/Archiver/ArchiveManager.php
+++ b/src/Composer/Package/Archiver/ArchiveManager.php
@@ -101,7 +101,7 @@ public function getPackageFilename(CompletePackageInterface $package): string
             $nameParts[] = substr(sha1($package->getSourceReference()), 0, 6);
         }
 
-        $name = implode('-', array_filter($nameParts, function ($p) {
+        $name = implode('-', array_filter($nameParts, function ($p): bool {
             return !empty($p);
         }));
 
diff --git a/src/Composer/Package/Archiver/BaseExcludeFilter.php b/src/Composer/Package/Archiver/BaseExcludeFilter.php
index ed63e12956e1..2fbd22796a48 100644
--- a/src/Composer/Package/Archiver/BaseExcludeFilter.php
+++ b/src/Composer/Package/Archiver/BaseExcludeFilter.php
@@ -95,7 +95,7 @@ function ($line) use ($lineParser) {
                 },
                 $lines
             ),
-            function ($pattern) {
+            function ($pattern): bool {
                 return $pattern !== null;
             }
         );
diff --git a/src/Composer/Package/BasePackage.php b/src/Composer/Package/BasePackage.php
index a3ec9c570f6b..f46cec9fdf64 100644
--- a/src/Composer/Package/BasePackage.php
+++ b/src/Composer/Package/BasePackage.php
@@ -274,7 +274,7 @@ public static function packageNameToRegexp($allowPattern, $wrap = '{^%s$}i')
     public static function packageNamesToRegexp(array $packageNames, $wrap = '{^(?:%s)$}iD')
     {
         $packageNames = array_map(
-            function ($packageName) {
+            function ($packageName): string {
                 return BasePackage::packageNameToRegexp($packageName, '%s');
             },
             $packageNames
diff --git a/src/Composer/Package/Locker.php b/src/Composer/Package/Locker.php
index 8003dff6ef84..1702d2ba906f 100644
--- a/src/Composer/Package/Locker.php
+++ b/src/Composer/Package/Locker.php
@@ -357,7 +357,7 @@ public function setLockData(array $packages, $devPackages, array $platformReqs,
     {
         // keep old default branch names normalized to DEFAULT_BRANCH_ALIAS for BC as that is how Composer 1 outputs the lock file
         // when loading the lock file the version is anyway ignored in Composer 2, so it has no adverse effect
-        $aliases = array_map(function ($alias) {
+        $aliases = array_map(function ($alias): array {
             if (in_array($alias['version'], array('dev-master', 'dev-trunk', 'dev-default'), true)) {
                 $alias['version'] = VersionParser::DEFAULT_BRANCH_ALIAS;
             }
diff --git a/src/Composer/Package/Version/VersionGuesser.php b/src/Composer/Package/Version/VersionGuesser.php
index ef6cfa8839dc..d5b0bf90792e 100644
--- a/src/Composer/Package/Version/VersionGuesser.php
+++ b/src/Composer/Package/Version/VersionGuesser.php
@@ -296,7 +296,7 @@ private function guessFeatureVersion(array $packageConfig, $version, array $bran
             // sort local branches first then remote ones
             // and sort numeric branches below named ones, to make sure if the branch has the same distance from main and 1.10 and 1.9 for example, main is picked
             // and sort using natural sort so that 1.10 will appear before 1.9
-            usort($branches, function ($a, $b) {
+            usort($branches, function ($a, $b): int {
                 $aRemote = 0 === strpos($a, 'remotes/');
                 $bRemote = 0 === strpos($b, 'remotes/');
 
diff --git a/src/Composer/Package/Version/VersionSelector.php b/src/Composer/Package/Version/VersionSelector.php
index 4a2968db2acd..431bdb851167 100644
--- a/src/Composer/Package/Version/VersionSelector.php
+++ b/src/Composer/Package/Version/VersionSelector.php
@@ -87,7 +87,7 @@ public function findBestCandidate($packageName, $targetPackageVersion = null, $p
 
         if ($this->platformConstraints && !($platformRequirementFilter instanceof IgnoreAllPlatformRequirementFilter)) {
             $platformConstraints = $this->platformConstraints;
-            $candidates = array_filter($candidates, function ($pkg) use ($platformConstraints, $platformRequirementFilter) {
+            $candidates = array_filter($candidates, function ($pkg) use ($platformConstraints, $platformRequirementFilter): bool {
                 $reqs = $pkg->getRequires();
 
                 foreach ($reqs as $name => $link) {
diff --git a/src/Composer/Question/StrictConfirmationQuestion.php b/src/Composer/Question/StrictConfirmationQuestion.php
index 5ec5577c14af..bcb339bda44e 100644
--- a/src/Composer/Question/StrictConfirmationQuestion.php
+++ b/src/Composer/Question/StrictConfirmationQuestion.php
@@ -86,7 +86,7 @@ private function getDefaultNormalizer(): callable
      */
     private function getDefaultValidator(): callable
     {
-        return function ($answer) {
+        return function ($answer): bool {
             if (!is_bool($answer)) {
                 throw new InvalidArgumentException('Please answer yes, y, no, or n.');
             }
diff --git a/src/Composer/Repository/ComposerRepository.php b/src/Composer/Repository/ComposerRepository.php
index a5a99f9f5c32..07035c51c902 100644
--- a/src/Composer/Repository/ComposerRepository.php
+++ b/src/Composer/Repository/ComposerRepository.php
@@ -350,7 +350,7 @@ public function getPackageNames($packageFilter = null)
              * @param list<string> $results
              * @return list<string>
              */
-            function (array $results) {
+            function (array $results): array {
                 return $results;
             }
         ;
@@ -361,7 +361,7 @@ function (array $results) {
                  * @param list<string> $results
                  * @return list<string>
                  */
-                function (array $results) use ($packageFilterRegex) {
+                function (array $results) use ($packageFilterRegex): array {
                     /** @var list<string> $results */
                     return Preg::grep($packageFilterRegex, $results);
                 }
@@ -905,7 +905,7 @@ private function loadAsyncPackages(array $packageNames, array $acceptableStabili
             }
 
             $promises[] = $this->asyncFetchFile($url, $cacheKey, $lastModified)
-                ->then(function ($response) use (&$packages, &$namesFound, $url, $cacheKey, $contents, $realName, $constraint, $acceptableStabilities, $stabilityFlags, $alreadyLoaded) {
+                ->then(function ($response) use (&$packages, &$namesFound, $url, $cacheKey, $contents, $realName, $constraint, $acceptableStabilities, $stabilityFlags, $alreadyLoaded): void {
                     $packagesSource = 'downloaded file ('.Url::sanitize($url).')';
 
                     if (true === $response) {
@@ -1095,7 +1095,7 @@ protected function loadRootServerFile($rootMaxAge = null)
             // Disables lazy-provider behavior as with available-packages, but may allow much more compact expression of packages covered by this repository.
             // Over-specifying covered packages is safe, but may result in increased traffic to your repository.
             if (!empty($data['available-package-patterns'])) {
-                $this->availablePackagePatterns = array_map(function ($pattern) {
+                $this->availablePackagePatterns = array_map(function ($pattern): string {
                     return BasePackage::packageNameToRegexp($pattern);
                 }, $data['available-package-patterns']);
                 $this->hasAvailablePackageList = true;
@@ -1493,7 +1493,7 @@ private function asyncFetchFile($filename, $cacheKey, $lastModifiedTime = null):
         $degradedMode = &$this->degradedMode;
         $eventDispatcher = $this->eventDispatcher;
 
-        $accept = function ($response) use ($io, $url, $filename, $cache, $cacheKey, $eventDispatcher) {
+        $accept = function ($response) use ($io, $url, $filename, $cache, $cacheKey, $eventDispatcher): array {
             // package not found is acceptable for a v2 protocol repository
             if ($response->getStatusCode() === 404) {
                 $this->packagesNotFoundCache[$filename] = true;
diff --git a/src/Composer/Repository/CompositeRepository.php b/src/Composer/Repository/CompositeRepository.php
index 67fdb73a27b6..e34ce7357995 100644
--- a/src/Composer/Repository/CompositeRepository.php
+++ b/src/Composer/Repository/CompositeRepository.php
@@ -42,7 +42,7 @@ public function __construct(array $repositories)
 
     public function getRepoName(): string
     {
-        return 'composite repo ('.implode(', ', array_map(function ($repo) {
+        return 'composite repo ('.implode(', ', array_map(function ($repo): string {
             return $repo->getRepoName();
         }, $this->repositories)).')';
     }
diff --git a/src/Composer/Repository/FilesystemRepository.php b/src/Composer/Repository/FilesystemRepository.php
index a6e949445a40..ea9a0eeb1eac 100644
--- a/src/Composer/Repository/FilesystemRepository.php
+++ b/src/Composer/Repository/FilesystemRepository.php
@@ -150,7 +150,7 @@ public function write($devMode, InstallationManager $installationManager)
         }
 
         sort($data['dev-package-names']);
-        usort($data['packages'], function ($a, $b) {
+        usort($data['packages'], function ($a, $b): int {
             return strcmp($a['name'], $b['name']);
         });
 
diff --git a/src/Composer/Repository/InstalledRepository.php b/src/Composer/Repository/InstalledRepository.php
index 63fc2c906e89..e99ed95db7f3 100644
--- a/src/Composer/Repository/InstalledRepository.php
+++ b/src/Composer/Repository/InstalledRepository.php
@@ -251,7 +251,7 @@ public function getDependents($needle, $constraint = null, $invert = false, $rec
 
     public function getRepoName(): string
     {
-        return 'installed repo ('.implode(', ', array_map(function ($repo) {
+        return 'installed repo ('.implode(', ', array_map(function ($repo): string {
             return $repo->getRepoName();
         }, $this->getRepositories())).')';
     }
diff --git a/src/Composer/Repository/PathRepository.php b/src/Composer/Repository/PathRepository.php
index 1b8489bb72f8..dcb9c82d54a7 100644
--- a/src/Composer/Repository/PathRepository.php
+++ b/src/Composer/Repository/PathRepository.php
@@ -251,7 +251,7 @@ private function getUrlMatches(): array
         }
 
         // Ensure environment-specific path separators are normalized to URL separators
-        return array_map(function ($val) {
+        return array_map(function ($val): string {
             return rtrim(str_replace(DIRECTORY_SEPARATOR, '/', $val), '/');
         }, glob($this->url, $flags));
     }
diff --git a/src/Composer/Repository/PlatformRepository.php b/src/Composer/Repository/PlatformRepository.php
index 3fc9d4be3397..4722f9899743 100644
--- a/src/Composer/Repository/PlatformRepository.php
+++ b/src/Composer/Repository/PlatformRepository.php
@@ -365,7 +365,7 @@ protected function initialize(): void
 
                 case 'libxml':
                     // ext/dom, ext/simplexml, ext/xmlreader and ext/xmlwriter use the same libxml as the ext/libxml
-                    $libxmlProvides = array_map(function ($extension) {
+                    $libxmlProvides = array_map(function ($extension): string {
                         return $extension . '-libxml';
                     }, array_intersect($loadedExtensions, array('dom', 'simplexml', 'xml', 'xmlreader', 'xmlwriter')));
                     $this->addLibrary($name, $this->runtime->getConstant('LIBXML_DOTTED_VERSION'), 'libxml library version', array(), $libxmlProvides);
diff --git a/src/Composer/Repository/Vcs/GitDriver.php b/src/Composer/Repository/Vcs/GitDriver.php
index b91508acd17b..cd69d5743d46 100644
--- a/src/Composer/Repository/Vcs/GitDriver.php
+++ b/src/Composer/Repository/Vcs/GitDriver.php
@@ -234,7 +234,7 @@ public static function supports(IOInterface $io, Config $config, $url, $deep = f
         GitUtil::cleanEnv();
 
         try {
-            $gitUtil->runCommand(function ($url) {
+            $gitUtil->runCommand(function ($url): string {
                 return 'git ls-remote --heads -- ' . ProcessExecutor::escape($url);
             }, $url, sys_get_temp_dir());
         } catch (\RuntimeException $e) {
diff --git a/src/Composer/Repository/Vcs/HgDriver.php b/src/Composer/Repository/Vcs/HgDriver.php
index 73bc426e5361..e9b83d6c547c 100644
--- a/src/Composer/Repository/Vcs/HgDriver.php
+++ b/src/Composer/Repository/Vcs/HgDriver.php
@@ -71,7 +71,7 @@ public function initialize()
                 $fs->removeDirectory($this->repoDir);
 
                 $repoDir = $this->repoDir;
-                $command = function ($url) use ($repoDir) {
+                $command = function ($url) use ($repoDir): string {
                     return sprintf('hg clone --noupdate -- %s %s', ProcessExecutor::escape($url), ProcessExecutor::escape($repoDir));
                 };
 
diff --git a/src/Composer/Util/AuthHelper.php b/src/Composer/Util/AuthHelper.php
index 59de345d7ab8..26eab08b2fb9 100644
--- a/src/Composer/Util/AuthHelper.php
+++ b/src/Composer/Util/AuthHelper.php
@@ -50,7 +50,7 @@ public function storeAuth($origin, $storeAuth): void
         } elseif ($storeAuth === 'prompt') {
             $answer = $this->io->askAndValidate(
                 'Do you want to store credentials for '.$origin.' in '.$configSource->getName().' ? [Yn] ',
-                function ($value) {
+                function ($value): string {
                     $input = strtolower(substr(trim($value), 0, 1));
                     if (in_array($input, array('y','n'))) {
                         return $input;
diff --git a/src/Composer/Util/ErrorHandler.php b/src/Composer/Util/ErrorHandler.php
index b60c728a0233..257f7ce29117 100644
--- a/src/Composer/Util/ErrorHandler.php
+++ b/src/Composer/Util/ErrorHandler.php
@@ -56,7 +56,7 @@ public static function handle($level, $message, $file, $line): bool
             self::$io->writeError('<warning>Deprecation Notice: '.$message.' in '.$file.':'.$line.'</warning>');
             if (self::$io->isVerbose()) {
                 self::$io->writeError('<warning>Stack trace:</warning>');
-                self::$io->writeError(array_filter(array_map(function ($a) {
+                self::$io->writeError(array_filter(array_map(function ($a): ?string {
                     if (isset($a['line'], $a['file'])) {
                         return '<warning> '.$a['file'].':'.$a['line'].'</warning>';
                     }
diff --git a/src/Composer/Util/Git.php b/src/Composer/Util/Git.php
index 4b92c2f775a6..27dc75a0dd9e 100644
--- a/src/Composer/Util/Git.php
+++ b/src/Composer/Util/Git.php
@@ -283,7 +283,7 @@ public function syncMirror($url, $dir)
         // update the repo if it is a valid git repository
         if (is_dir($dir) && 0 === $this->process->execute('git rev-parse --git-dir', $output, $dir) && trim($output) === '.') {
             try {
-                $commandCallable = function ($url) {
+                $commandCallable = function ($url): string {
                     $sanitizedUrl = Preg::replace('{://([^@]+?):(.+?)@}', '://', $url);
 
                     return sprintf('git remote set-url origin -- %s && git remote update --prune origin && git remote set-url origin -- %s && git gc --auto', ProcessExecutor::escape($url), ProcessExecutor::escape($sanitizedUrl));
@@ -301,7 +301,7 @@ public function syncMirror($url, $dir)
         // clean up directory and do a fresh clone into it
         $this->filesystem->removeDirectory($dir);
 
-        $commandCallable = function ($url) use ($dir) {
+        $commandCallable = function ($url) use ($dir): string {
             return sprintf('git clone --mirror -- %s %s', ProcessExecutor::escape($url), ProcessExecutor::escape($dir));
         };
 
diff --git a/src/Composer/Util/HttpDownloader.php b/src/Composer/Util/HttpDownloader.php
index dcebffa4bf55..b919680f2937 100644
--- a/src/Composer/Util/HttpDownloader.php
+++ b/src/Composer/Util/HttpDownloader.php
@@ -216,13 +216,13 @@ private function addJob($request, $sync = false): array
         $rfs = $this->rfs;
 
         if ($this->canUseCurl($job)) {
-            $resolver = function ($resolve, $reject) use (&$job) {
+            $resolver = function ($resolve, $reject) use (&$job): void {
                 $job['status'] = HttpDownloader::STATUS_QUEUED;
                 $job['resolve'] = $resolve;
                 $job['reject'] = $reject;
             };
         } else {
-            $resolver = function ($resolve, $reject) use (&$job, $rfs) {
+            $resolver = function ($resolve, $reject) use (&$job, $rfs): void {
                 // start job
                 $url = $job['request']['url'];
                 $options = $job['request']['options'];
@@ -248,7 +248,7 @@ private function addJob($request, $sync = false): array
 
         $curl = $this->curl;
 
-        $canceler = function () use (&$job, $curl) {
+        $canceler = function () use (&$job, $curl): void {
             if ($job['status'] === HttpDownloader::STATUS_QUEUED) {
                 $job['status'] = HttpDownloader::STATUS_ABORTED;
             }
@@ -270,7 +270,7 @@ private function addJob($request, $sync = false): array
             $this->markJobDone();
 
             return $response;
-        }, function ($e) use (&$job) {
+        }, function ($e) use (&$job): void {
             $job['status'] = HttpDownloader::STATUS_FAILED;
             $job['exception'] = $e;
 
diff --git a/src/Composer/Util/Platform.php b/src/Composer/Util/Platform.php
index 1f582a73e00a..d237f8ea10b3 100644
--- a/src/Composer/Util/Platform.php
+++ b/src/Composer/Util/Platform.php
@@ -82,7 +82,7 @@ public static function expandPath($path): string
             return self::getUserDirectory() . substr($path, 1);
         }
 
-        return Preg::replaceCallback('#^(\$|(?P<percent>%))(?P<var>\w++)(?(percent)%)(?P<path>.*)#', function ($matches) {
+        return Preg::replaceCallback('#^(\$|(?P<percent>%))(?P<var>\w++)(?(percent)%)(?P<path>.*)#', function ($matches): string {
             // Treat HOME as an alias for USERPROFILE on Windows for legacy reasons
             if (Platform::isWindows() && $matches['var'] == 'HOME') {
                 return (Platform::getEnv('HOME') ?: Platform::getEnv('USERPROFILE')) . $matches['path'];
diff --git a/src/Composer/Util/ProcessExecutor.php b/src/Composer/Util/ProcessExecutor.php
index 809de9810621..fb661bac4d7f 100644
--- a/src/Composer/Util/ProcessExecutor.php
+++ b/src/Composer/Util/ProcessExecutor.php
@@ -153,13 +153,13 @@ public function executeAsync($command, $cwd = null)
             'cwd' => $cwd,
         );
 
-        $resolver = function ($resolve, $reject) use (&$job) {
+        $resolver = function ($resolve, $reject) use (&$job): void {
             $job['status'] = ProcessExecutor::STATUS_QUEUED;
             $job['resolve'] = $resolve;
             $job['reject'] = $reject;
         };
 
-        $canceler = function () use (&$job) {
+        $canceler = function () use (&$job): void {
             if ($job['status'] === ProcessExecutor::STATUS_QUEUED) {
                 $job['status'] = ProcessExecutor::STATUS_ABORTED;
             }
@@ -190,7 +190,7 @@ public function executeAsync($command, $cwd = null)
             $this->markJobDone();
 
             return $job['process'];
-        }, function ($e) use (&$job) {
+        }, function ($e) use (&$job): void {
             $job['status'] = ProcessExecutor::STATUS_FAILED;
 
             $this->markJobDone();
@@ -407,7 +407,7 @@ private function outputCommandRun($command, ?string $cwd, bool $async): void
         }
 
         $commandString = is_string($command) ? $command : implode(' ', array_map(self::class.'::escape', $command));
-        $safeCommand = Preg::replaceCallback('{://(?P<user>[^:/\s]+):(?P<password>[^@\s/]+)@}i', function ($m) {
+        $safeCommand = Preg::replaceCallback('{://(?P<user>[^:/\s]+):(?P<password>[^@\s/]+)@}i', function ($m): string {
             // if the username looks like a long (12char+) hex string, or a modern github token (e.g. ghp_xxx) we obfuscate that
             if (Preg::isMatch('{^([a-f0-9]{12,}|gh[a-z]_[a-zA-Z0-9_]+)$}', $m['user'])) {
                 return '://***:***@';
diff --git a/src/Composer/Util/RemoteFilesystem.php b/src/Composer/Util/RemoteFilesystem.php
index 464198f579f9..1d6866f7a583 100644
--- a/src/Composer/Util/RemoteFilesystem.php
+++ b/src/Composer/Util/RemoteFilesystem.php
@@ -290,7 +290,7 @@ protected function get($originUrl, $fileUrl, $additionalOptions = array(), $file
         $errorMessage = '';
         $errorCode = 0;
         $result = false;
-        set_error_handler(function ($code, $msg) use (&$errorMessage) {
+        set_error_handler(function ($code, $msg) use (&$errorMessage): bool {
             if ($errorMessage) {
                 $errorMessage .= "\n";
             }
@@ -445,7 +445,7 @@ protected function get($originUrl, $fileUrl, $additionalOptions = array(), $file
             }
 
             $errorMessage = '';
-            set_error_handler(function ($code, $msg) use (&$errorMessage) {
+            set_error_handler(function ($code, $msg) use (&$errorMessage): bool {
                 if ($errorMessage) {
                     $errorMessage .= "\n";
                 }
diff --git a/src/Composer/Util/StreamContextFactory.php b/src/Composer/Util/StreamContextFactory.php
index f0d8bbe93088..7448990d3df9 100644
--- a/src/Composer/Util/StreamContextFactory.php
+++ b/src/Composer/Util/StreamContextFactory.php
@@ -245,7 +245,7 @@ private static function fixHttpHeaderField($header): array
         if (!is_array($header)) {
             $header = explode("\r\n", $header);
         }
-        uasort($header, function ($el) {
+        uasort($header, function ($el): int {
             return stripos($el, 'content-type') === 0 ? 1 : -1;
         });
 
diff --git a/src/Composer/Util/TlsHelper.php b/src/Composer/Util/TlsHelper.php
index bf3aa1ea3e94..697a66b17552 100644
--- a/src/Composer/Util/TlsHelper.php
+++ b/src/Composer/Util/TlsHelper.php
@@ -78,7 +78,7 @@ public static function getCertificateNames($certificate): ?array
 
         if (isset($info['extensions']['subjectAltName'])) {
             $subjectAltNames = Preg::split('{\s*,\s*}', $info['extensions']['subjectAltName']);
-            $subjectAltNames = array_filter(array_map(function ($name) {
+            $subjectAltNames = array_filter(array_map(function ($name): ?string {
                 if (0 === strpos($name, 'DNS:')) {
                     return strtolower(ltrim(substr($name, 4)));
                 }
@@ -179,7 +179,7 @@ private static function certNameMatcher($certName): ?callable
 
         if (0 === $wildcards) {
             // Literal match.
-            return function ($hostname) use ($certName) {
+            return function ($hostname) use ($certName): bool {
                 return $hostname === $certName;
             };
         }
@@ -203,7 +203,7 @@ private static function certNameMatcher($certName): ?callable
             $wildcardRegex = str_replace('\\*', '[a-z0-9-]+', $wildcardRegex);
             $wildcardRegex = "{^{$wildcardRegex}$}";
 
-            return function ($hostname) use ($wildcardRegex) {
+            return function ($hostname) use ($wildcardRegex): bool {
                 return Preg::isMatch($wildcardRegex, $hostname);
             };
         }
diff --git a/src/Composer/Util/Url.php b/src/Composer/Util/Url.php
index 19e8f5065d1f..d118054d24b6 100644
--- a/src/Composer/Util/Url.php
+++ b/src/Composer/Util/Url.php
@@ -114,7 +114,7 @@ public static function sanitize($url): string
         // e.g. https://api.github.com/repositories/9999999999?access_token=github_token
         $url = Preg::replace('{([&?]access_token=)[^&]+}', '$1***', $url);
 
-        $url = Preg::replaceCallback('{^(?P<prefix>[a-z0-9]+://)?(?P<user>[^:/\s@]+):(?P<password>[^@\s/]+)@}i', function ($m) {
+        $url = Preg::replaceCallback('{^(?P<prefix>[a-z0-9]+://)?(?P<user>[^:/\s@]+):(?P<password>[^@\s/]+)@}i', function ($m): string {
             // if the username looks like a long (12char+) hex string, or a modern github token (e.g. ghp_xxx) we obfuscate that
             if (Preg::isMatch('{^([a-f0-9]{12,}|gh[a-z]_[a-zA-Z0-9_]+)$}', $m['user'])) {
                 return $m['prefix'].'***:***@';

From 7c5b10a8576e8d66b2fee26ded7a6b48179ce3da Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Mon, 21 Feb 2022 13:18:31 +0100
Subject: [PATCH 2/8] Always return PromiseInterface

---
 src/Composer/Downloader/DownloadManager.php | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/Composer/Downloader/DownloadManager.php b/src/Composer/Downloader/DownloadManager.php
index 0a7d6c9abc2e..41e61e0ad218 100644
--- a/src/Composer/Downloader/DownloadManager.php
+++ b/src/Composer/Downloader/DownloadManager.php
@@ -330,9 +330,14 @@ public function update(PackageInterface $initial, PackageInterface $target, $tar
         // if downloader type changed, or update failed and user asks for reinstall,
         // we wipe the dir and do a new install instead of updating it
         $promise = $initialDownloader->remove($initial, $targetDir);
-        if ($promise) {
-            return $promise->then(function ($res) use ($target, $targetDir): ?\React\Promise\PromiseInterface {
-                return $this->install($target, $targetDir);
+        if ($promise instanceof PromiseInterface) {
+            return $promise->then(function ($res) use ($target, $targetDir): PromiseInterface {
+                $promise = $this->install($target, $targetDir);
+                if ($promise instanceof PromiseInterface) {
+                    return $promise;
+                }
+                
+                return \React\Promise\resolve();
             });
         }
 

From 4d5328a74d5772fc2855a2c994b39ebffb563d1c Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Mon, 21 Feb 2022 13:20:08 +0100
Subject: [PATCH 3/8] Always return promise

---
 src/Composer/Downloader/FileDownloader.php | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/Composer/Downloader/FileDownloader.php b/src/Composer/Downloader/FileDownloader.php
index 5b184ec30ffc..ab347d23da37 100644
--- a/src/Composer/Downloader/FileDownloader.php
+++ b/src/Composer/Downloader/FileDownloader.php
@@ -407,10 +407,13 @@ public function update(PackageInterface $initial, PackageInterface $target, $pat
             $promise = \React\Promise\resolve();
         }
 
-        return $promise->then(function () use ($target, $path): ?\React\Promise\PromiseInterface {
+        return $promise->then(function () use ($target, $path): PromiseInterface {
             $promise = $this->install($target, $path, false);
+            if ($promise instanceof PromiseInterface) {
+                return $promise;
+            }
 
-            return $promise;
+            return \React\Promise\resolve();
         });
     }
 

From 96ab7dcefe45f041e1b9766f99948ec09fcf619e Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Mon, 21 Feb 2022 13:23:00 +0100
Subject: [PATCH 4/8] Always return promise

---
 src/Composer/Installer/LibraryInstaller.php | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/Composer/Installer/LibraryInstaller.php b/src/Composer/Installer/LibraryInstaller.php
index 484daf8c837c..ce65b2d33a9d 100644
--- a/src/Composer/Installer/LibraryInstaller.php
+++ b/src/Composer/Installer/LibraryInstaller.php
@@ -288,8 +288,13 @@ protected function updateCode(PackageInterface $initial, PackageInterface $targe
                     $promise = \React\Promise\resolve();
                 }
 
-                return $promise->then(function () use ($target): ?\React\Promise\PromiseInterface {
-                    return $this->installCode($target);
+                return $promise->then(function () use ($target): PromiseInterface {
+                    $promise = $this->installCode($target);
+                    if ($promise instanceof PromiseInterface) {
+                        return $promise;
+                    }
+
+                    return \React\Promise\resolve()
                 });
             }
 

From b3ddcedae9afcf289e03cafa95ec8af06e0ccfb0 Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Mon, 21 Feb 2022 13:23:03 +0100
Subject: [PATCH 5/8] Always return promise

---
 src/Composer/Installer/InstallationManager.php | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/Composer/Installer/InstallationManager.php b/src/Composer/Installer/InstallationManager.php
index 8102e4537a6d..69e8ae287d35 100644
--- a/src/Composer/Installer/InstallationManager.php
+++ b/src/Composer/Installer/InstallationManager.php
@@ -548,8 +548,13 @@ public function update(InstalledRepositoryInterface $repo, UpdateOperation $oper
             }
 
             $installer = $this->getInstaller($targetType);
-            $promise = $promise->then(function () use ($installer, $repo, $target): ?\React\Promise\PromiseInterface {
-                return $installer->install($repo, $target);
+            $promise = $promise->then(function () use ($installer, $repo, $target): PromiseInterface {
+                $promise = $installer->install($repo, $target);
+                if ($promise instanceof PromiseInterface) {
+                    return $promise;
+                }
+                
+                return \React\Promise\resolve()
             });
         }
 

From 3e79b197543f33a5ed2f3b43f4cd7e7607f2c93b Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Mon, 21 Feb 2022 13:24:53 +0100
Subject: [PATCH 6/8] Fix error in ComposerRepo

---
 src/Composer/Repository/ComposerRepository.php | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/Composer/Repository/ComposerRepository.php b/src/Composer/Repository/ComposerRepository.php
index 07035c51c902..9e6adbaf6ac3 100644
--- a/src/Composer/Repository/ComposerRepository.php
+++ b/src/Composer/Repository/ComposerRepository.php
@@ -1493,7 +1493,10 @@ private function asyncFetchFile($filename, $cacheKey, $lastModifiedTime = null):
         $degradedMode = &$this->degradedMode;
         $eventDispatcher = $this->eventDispatcher;
 
-        $accept = function ($response) use ($io, $url, $filename, $cache, $cacheKey, $eventDispatcher): array {
+        /**
+         * @return array<mixed>|true true if the response was a 304 and the cache is fresh
+         */
+        $accept = function ($response) use ($io, $url, $filename, $cache, $cacheKey, $eventDispatcher) {
             // package not found is acceptable for a v2 protocol repository
             if ($response->getStatusCode() === 404) {
                 $this->packagesNotFoundCache[$filename] = true;

From 009927bd35e586a2c9602cb138397652882378ab Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Mon, 21 Feb 2022 13:31:50 +0100
Subject: [PATCH 7/8] Fix syntax error

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

diff --git a/src/Composer/Installer/InstallationManager.php b/src/Composer/Installer/InstallationManager.php
index 69e8ae287d35..788d367e77b4 100644
--- a/src/Composer/Installer/InstallationManager.php
+++ b/src/Composer/Installer/InstallationManager.php
@@ -554,7 +554,7 @@ public function update(InstalledRepositoryInterface $repo, UpdateOperation $oper
                     return $promise;
                 }
                 
-                return \React\Promise\resolve()
+                return \React\Promise\resolve();
             });
         }
 

From d12dde5c7bcae1c1392c733dc035e17561c7b48b Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Mon, 21 Feb 2022 13:32:59 +0100
Subject: [PATCH 8/8] Fix syntax

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

diff --git a/src/Composer/Installer/LibraryInstaller.php b/src/Composer/Installer/LibraryInstaller.php
index ce65b2d33a9d..f5525341d948 100644
--- a/src/Composer/Installer/LibraryInstaller.php
+++ b/src/Composer/Installer/LibraryInstaller.php
@@ -294,7 +294,7 @@ protected function updateCode(PackageInterface $initial, PackageInterface $targe
                         return $promise;
                     }
 
-                    return \React\Promise\resolve()
+                    return \React\Promise\resolve();
                 });
             }