From 10555ecff358e854596e21c21635bec877f4936d Mon Sep 17 00:00:00 2001
From: Yanick Witschi <yanick.witschi@terminal42.ch>
Date: Fri, 24 Apr 2020 17:42:24 +0200
Subject: [PATCH] Make sure there's always a constraint

---
 src/Composer/DependencyResolver/PoolBuilder.php | 6 +-----
 src/Composer/DependencyResolver/Request.php     | 3 ++-
 src/Composer/Package/Link.php                   | 5 +++--
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/src/Composer/DependencyResolver/PoolBuilder.php b/src/Composer/DependencyResolver/PoolBuilder.php
index 727f086d8..575e89ce6 100644
--- a/src/Composer/DependencyResolver/PoolBuilder.php
+++ b/src/Composer/DependencyResolver/PoolBuilder.php
@@ -294,10 +294,6 @@ class PoolBuilder
                     $this->io->writeError('<warning>Dependency "'.$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>');
                 }
             } else {
-                if (null === $this->loadedNames[$require] || null === $linkConstraint) {
-                    unset($this->loadedNames[$require]);
-                }
-
                 if (!$this->loadedNames[$require]->matches($linkConstraint)) {
                     $loadNames[$require] = MultiConstraint::create(array($this->loadedNames[$require], $linkConstraint), false);
                     unset($this->loadedNames[$require]);
@@ -313,7 +309,7 @@ class PoolBuilder
                 if (isset($this->loadedNames[$replace]) && isset($this->skippedLoad[$replace])) {
                     if ($request->getUpdateAllowTransitiveRootDependencies() || !$this->isRootRequire($request, $this->skippedLoad[$replace])) {
                         $this->unfixPackage($request, $replace);
-                        $loadNames[$replace] = null;
+                        $loadNames[$replace] = $link->getConstraint();
                     } elseif (!$request->getUpdateAllowTransitiveRootDependencies() && $this->isRootRequire($request, $replace) && !isset($this->updateAllowWarned[$replace])) {
                         $this->updateAllowWarned[$replace] = true;
                         $this->io->writeError('<warning>Dependency "'.$replace.'" 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>');
diff --git a/src/Composer/DependencyResolver/Request.php b/src/Composer/DependencyResolver/Request.php
index 5782c3ff1..959ba884b 100644
--- a/src/Composer/DependencyResolver/Request.php
+++ b/src/Composer/DependencyResolver/Request.php
@@ -17,6 +17,7 @@ use Composer\Package\PackageInterface;
 use Composer\Package\RootAliasPackage;
 use Composer\Repository\LockArrayRepository;
 use Composer\Semver\Constraint\ConstraintInterface;
+use Composer\Semver\Constraint\EmptyConstraint;
 
 /**
  * @author Nils Adermann <naderman@naderman.de>
@@ -55,7 +56,7 @@ class Request
     public function requireName($packageName, ConstraintInterface $constraint = null)
     {
         $packageName = strtolower($packageName);
-        $this->requires[$packageName] = $constraint;
+        $this->requires[$packageName] = $constraint ? $constraint : new EmptyConstraint();
     }
 
     /**
diff --git a/src/Composer/Package/Link.php b/src/Composer/Package/Link.php
index 5a6c683cc..03ea3edff 100644
--- a/src/Composer/Package/Link.php
+++ b/src/Composer/Package/Link.php
@@ -13,6 +13,7 @@
 namespace Composer\Package;
 
 use Composer\Semver\Constraint\ConstraintInterface;
+use Composer\Semver\Constraint\EmptyConstraint;
 
 /**
  * Represents a link between two packages, represented by their names
@@ -59,7 +60,7 @@ class Link
     {
         $this->source = strtolower($source);
         $this->target = strtolower($target);
-        $this->constraint = $constraint;
+        $this->constraint = $constraint ? $constraint : new EmptyConstraint();
         $this->description = $description;
         $this->prettyConstraint = $prettyConstraint;
     }
@@ -89,7 +90,7 @@ class Link
     }
 
     /**
-     * @return ConstraintInterface|null
+     * @return ConstraintInterface
      */
     public function getConstraint()
     {