diff --git a/src/Composer/DependencyResolver/PoolBuilder.php b/src/Composer/DependencyResolver/PoolBuilder.php
index 06c50bdeb..36c991816 100644
--- a/src/Composer/DependencyResolver/PoolBuilder.php
+++ b/src/Composer/DependencyResolver/PoolBuilder.php
@@ -48,7 +48,7 @@ class PoolBuilder
     private $skippedLoad = array();
     private $updateAllowWarned = array();
 
-    public function __construct(array $acceptableStabilities, array $stabilityFlags, array $rootAliases, array $rootReferences, EventDispatcher $eventDispatcher = null, IOInterface $io = null)
+    public function __construct(array $acceptableStabilities, array $stabilityFlags, array $rootAliases, array $rootReferences, IOInterface $io = null, EventDispatcher $eventDispatcher = null)
     {
         $this->acceptableStabilities = $acceptableStabilities;
         $this->stabilityFlags = $stabilityFlags;
@@ -244,7 +244,7 @@ class PoolBuilder
                 if ($request->getUpdateAllowTransitiveRootDependencies() || !$this->isRootRequire($request, $require)) {
                     $this->unfixPackage($request, $require);
                     $loadNames[$require] = null;
-                } elseif (!$request->getUpdateAllowTransitiveRootDependencies() && $this->isRootRequire($request, $require) && !isset($this->updateAllowWarned[$require]) && $this->io) {
+                } elseif (!$request->getUpdateAllowTransitiveRootDependencies() && $this->isRootRequire($request, $require) && !isset($this->updateAllowWarned[$require])) {
                     $this->updateAllowWarned[$require] = true;
                     $this->io->writeError('<warning>Dependency "'.$require.'" is also a root requirement. Package has not been listed as an update argument, so keeping locked at old version. Use --with-all-dependencies to include root dependencies.</warning>');
                 }
@@ -275,7 +275,7 @@ class PoolBuilder
                         $loadNames[$replace] = null;
                         // TODO should we try to merge constraints here?
                         $this->nameConstraints[$replace] = null;
-                    } elseif (!$request->getUpdateAllowTransitiveRootDependencies() && $this->isRootRequire($request, $replace) && !isset($this->updateAllowWarned[$require]) && $this->io) {
+                    } elseif (!$request->getUpdateAllowTransitiveRootDependencies() && $this->isRootRequire($request, $replace) && !isset($this->updateAllowWarned[$require])) {
                         $this->updateAllowWarned[$replace] = true;
                         $this->io->writeError('<warning>Dependency "'.$require.'" is also a root requirement. Package has not been listed as an update argument, so keeping locked at old version. Use --with-all-dependencies to include root dependencies.</warning>');
                     }
@@ -315,27 +315,25 @@ class PoolBuilder
 
     private function warnAboutNonMatchingUpdateAllowList(Request $request)
     {
-        if ($this->io) {
-            foreach ($this->updateAllowList as $pattern => $void) {
-                $patternRegexp = BasePackage::packageNameToRegexp($pattern);
-                // update pattern matches a locked package? => all good
-                foreach ($request->getLockedRepository()->getPackages() as $package) {
-                    if (preg_match($patternRegexp, $package->getName())) {
-                        continue 2;
-                    }
+        foreach ($this->updateAllowList as $pattern => $void) {
+            $patternRegexp = BasePackage::packageNameToRegexp($pattern);
+            // update pattern matches a locked package? => all good
+            foreach ($request->getLockedRepository()->getPackages() as $package) {
+                if (preg_match($patternRegexp, $package->getName())) {
+                    continue 2;
                 }
-                // update pattern matches a root require? => all good, probably a new package
-                foreach ($request->getRequires() as $packageName => $constraint) {
-                    if (preg_match($patternRegexp, $packageName)) {
-                        continue 2;
-                    }
-                }
-                if (strpos($pattern, '*') !== false) {
-                    $this->io->writeError('<warning>Pattern "' . $pattern . '" listed for update does not match any locked packages.</warning>');
-                } else {
-                    $this->io->writeError('<warning>Package "' . $pattern . '" listed for update is not locked.</warning>');
+            }
+            // update pattern matches a root require? => all good, probably a new package
+            foreach ($request->getRequires() as $packageName => $constraint) {
+                if (preg_match($patternRegexp, $packageName)) {
+                    continue 2;
                 }
             }
+            if (strpos($pattern, '*') !== false) {
+                $this->io->writeError('<warning>Pattern "' . $pattern . '" listed for update does not match any locked packages.</warning>');
+            } else {
+                $this->io->writeError('<warning>Package "' . $pattern . '" listed for update is not locked.</warning>');
+            }
         }
     }
 
diff --git a/src/Composer/Installer.php b/src/Composer/Installer.php
index 500a9a827..3937a15b0 100644
--- a/src/Composer/Installer.php
+++ b/src/Composer/Installer.php
@@ -393,7 +393,7 @@ class Installer
             $request->setUpdateAllowList($this->updateAllowList, $this->updateAllowTransitiveDependencies);
         }
 
-        $pool = $repositorySet->createPool($request, $this->eventDispatcher, $this->io);
+        $pool = $repositorySet->createPool($request, $this->io, $this->eventDispatcher);
 
         // solve dependencies
         $solver = new Solver($policy, $pool, $this->io, $repositorySet);
@@ -612,7 +612,7 @@ class Installer
                 $request->requireName($link->getTarget(), $link->getConstraint());
             }
 
-            $pool = $repositorySet->createPool($request, $this->eventDispatcher, $this->io);
+            $pool = $repositorySet->createPool($request, $this->io, $this->eventDispatcher);
 
             // solve dependencies
             $solver = new Solver($policy, $pool, $this->io, $repositorySet);
diff --git a/src/Composer/Repository/RepositorySet.php b/src/Composer/Repository/RepositorySet.php
index 7e5d6437d..b0489e99b 100644
--- a/src/Composer/Repository/RepositorySet.php
+++ b/src/Composer/Repository/RepositorySet.php
@@ -17,6 +17,7 @@ use Composer\DependencyResolver\PoolBuilder;
 use Composer\DependencyResolver\Request;
 use Composer\EventDispatcher\EventDispatcher;
 use Composer\IO\IOInterface;
+use Composer\IO\NullIO;
 use Composer\Package\BasePackage;
 use Composer\Package\Version\VersionParser;
 use Composer\Repository\CompositeRepository;
@@ -186,9 +187,9 @@ class RepositorySet
      *
      * @return Pool
      */
-    public function createPool(Request $request, EventDispatcher $eventDispatcher = null, IOInterface $io = null)
+    public function createPool(Request $request, IOInterface $io, EventDispatcher $eventDispatcher = null)
     {
-        $poolBuilder = new PoolBuilder($this->acceptableStabilities, $this->stabilityFlags, $this->rootAliases, $this->rootReferences, $eventDispatcher, $io);
+        $poolBuilder = new PoolBuilder($this->acceptableStabilities, $this->stabilityFlags, $this->rootAliases, $this->rootReferences, $io, $eventDispatcher);
 
         foreach ($this->repositories as $repo) {
             if (($repo instanceof InstalledRepositoryInterface || $repo instanceof InstalledRepository) && !$this->allowInstalledRepositories) {
@@ -237,6 +238,6 @@ class RepositorySet
             $request->requireName($packageName);
         }
 
-        return $this->createPool($request);
+        return $this->createPool($request, new NullIO());
     }
 }
diff --git a/tests/Composer/Test/DependencyResolver/PoolBuilderTest.php b/tests/Composer/Test/DependencyResolver/PoolBuilderTest.php
index c55431b6e..f51661db6 100644
--- a/tests/Composer/Test/DependencyResolver/PoolBuilderTest.php
+++ b/tests/Composer/Test/DependencyResolver/PoolBuilderTest.php
@@ -89,7 +89,7 @@ class PoolBuilderTest extends TestCase
             $request->fixPackage($loadPackage($fixedPackage));
         }
 
-        $pool = $repositorySet->createPool($request);
+        $pool = $repositorySet->createPool($request, new NullIO());
         for ($i = 1, $count = count($pool); $i <= $count; $i++) {
             $result[] = $pool->packageById($i);
         }
diff --git a/tests/Composer/Test/DependencyResolver/SolverTest.php b/tests/Composer/Test/DependencyResolver/SolverTest.php
index 46d882e9f..3090d9d83 100644
--- a/tests/Composer/Test/DependencyResolver/SolverTest.php
+++ b/tests/Composer/Test/DependencyResolver/SolverTest.php
@@ -890,8 +890,9 @@ class SolverTest extends TestCase
 
     protected function createSolver()
     {
-        $this->pool = $this->repoSet->createPool($this->request);
-        $this->solver = new Solver($this->policy, $this->pool, new NullIO());
+        $io = new NullIO();
+        $this->pool = $this->repoSet->createPool($this->request, $io);
+        $this->solver = new Solver($this->policy, $this->pool, $io);
     }
 
     protected function checkSolverResult(array $expected)