Refactor the handling of conflict rules in the solver

Conflict rules are not added in the solver based on the packages loaded in the
solver by require rules, instead of loading remote metadata for them. This has
2 benefits:

- it reduces the number of conflict rules in the solver in case of conflict
  rules targetting packages which are not required
- it fixes the behavior of replaces, which is meant to conflict with all
  versions of the replaced package, without introducing a performance
  regression (this behavior was changed when optimizing composer in the past).

src/Composer/DependencyResolver/Pool.php

@@ -317,12 +317,12 @@ class Pool implements \Countable
      * Checks if the package matches the given constraint directly or through
      * provided or replaced packages
      *
-     * @param  array|PackageInterface $candidate
+     * @param  PackageInterface       $candidate
      * @param  string                 $name       Name of the package to be matched
      * @param  ConstraintInterface    $constraint The constraint to verify
      * @return int                    One of the MATCH* constants of this class or 0 if there is no match
      */
-    private function match($candidate, $name, ConstraintInterface $constraint = null, $bypassFilters)
+    public function match($candidate, $name, ConstraintInterface $constraint = null, $bypassFilters)
     {
         $candidateName = $candidate->getName();
         $candidateVersion = $candidate->getVersion();

src/Composer/DependencyResolver/RuleSetGenerator.php

@@ -28,6 +28,9 @@ class RuleSetGenerator
     protected $installedMap;
     protected $whitelistedMap;
     protected $addedMap;
+    protected $conflictAddedMap;
+    protected $addedPackages;
+    protected $addedPackagesByNames;
 
     public function __construct(PolicyInterface $policy, Pool $pool)
     {
@@ -185,6 +188,7 @@ class RuleSetGenerator
         $workQueue->enqueue($package);
 
         while (!$workQueue->isEmpty()) {
+            /** @var PackageInterface $package */
             $package = $workQueue->dequeue();
             if (isset($this->addedMap[$package->id])) {
                 continue;
@@ -192,6 +196,11 @@ class RuleSetGenerator
 
             $this->addedMap[$package->id] = true;
 
+            $this->addedPackages[] = $package;
+            foreach ($package->getNames() as $name) {
+                $this->addedPackagesByNames[$name][] = $package;
+            }
+
             foreach ($package->getRequires() as $link) {
                 if ($ignorePlatformReqs && preg_match(PlatformRepository::PLATFORM_PACKAGE_REGEX, $link->getTarget())) {
                     continue;
@@ -206,11 +215,41 @@ class RuleSetGenerator
                 }
             }
 
+            $packageName = $package->getName();
+            $obsoleteProviders = $this->pool->whatProvides($packageName, null);
+
+            foreach ($obsoleteProviders as $provider) {
+                if ($provider === $package) {
+                    continue;
+                }
+
+                if (($package instanceof AliasPackage) && $package->getAliasOf() === $provider) {
+                    $this->addRule(RuleSet::TYPE_PACKAGE, $this->createRequireRule($package, array($provider), Rule::RULE_PACKAGE_ALIAS, $package));
+                } elseif (!$this->obsoleteImpossibleForAlias($package, $provider)) {
+                    $reason = ($packageName == $provider->getName()) ? Rule::RULE_PACKAGE_SAME_NAME : Rule::RULE_PACKAGE_IMPLICIT_OBSOLETES;
+                    $this->addRule(RuleSet::TYPE_PACKAGE, $this->createRule2Literals($package, $provider, $reason, $package));
+                }
+            }
+        }
+    }
+
+    protected function addConflictRules()
+    {
+        /** @var PackageInterface $package */
+        foreach ($this->addedPackages as $package) {
             foreach ($package->getConflicts() as $link) {
-                $possibleConflicts = $this->pool->whatProvides($link->getTarget(), $link->getConstraint());
+                if (!isset($this->addedPackagesByNames[$link->getTarget()])) {
+                    continue;
+                }
+
+                /** @var PackageInterface $possibleConflict */
+                foreach ($this->addedPackagesByNames[$link->getTarget()] as $possibleConflict) {
+                    $conflictMatch = $this->pool->match($possibleConflict, $link->getTarget(), $link->getConstraint(), true);
+
+                    if ($conflictMatch === Pool::MATCH || $conflictMatch === Pool::MATCH_REPLACE) {
+                        $this->addRule(RuleSet::TYPE_PACKAGE, $this->createRule2Literals($package, $possibleConflict, Rule::RULE_PACKAGE_CONFLICT, $link));
+                    }
 
-                foreach ($possibleConflicts as $conflict) {
-                    $this->addRule(RuleSet::TYPE_PACKAGE, $this->createRule2Literals($package, $conflict, Rule::RULE_PACKAGE_CONFLICT, $link));
                 }
             }
 
@@ -218,9 +257,12 @@ class RuleSetGenerator
             $isInstalled = isset($this->installedMap[$package->id]);
 
             foreach ($package->getReplaces() as $link) {
-                $obsoleteProviders = $this->pool->whatProvides($link->getTarget(), $link->getConstraint());
+                if (!isset($this->addedPackagesByNames[$link->getTarget()])) {
+                    continue;
+                }
 
-                foreach ($obsoleteProviders as $provider) {
+                /** @var PackageInterface $possibleConflict */
+                foreach ($this->addedPackagesByNames[$link->getTarget()] as $provider) {
                     if ($provider === $package) {
                         continue;
                     }
@@ -231,22 +273,6 @@ class RuleSetGenerator
                     }
                 }
             }
-
-            $packageName = $package->getName();
-            $obsoleteProviders = $this->pool->whatProvides($packageName, null);
-
-            foreach ($obsoleteProviders as $provider) {
-                if ($provider === $package) {
-                    continue;
-                }
-
-                if (($package instanceof AliasPackage) && $package->getAliasOf() === $provider) {
-                    $this->addRule(RuleSet::TYPE_PACKAGE, $this->createRequireRule($package, array($provider), Rule::RULE_PACKAGE_ALIAS, $package));
-                } elseif (!$this->obsoleteImpossibleForAlias($package, $provider)) {
-                    $reason = ($packageName == $provider->getName()) ? Rule::RULE_PACKAGE_SAME_NAME : Rule::RULE_PACKAGE_IMPLICIT_OBSOLETES;
-                    $this->addRule(RuleSet::TYPE_PACKAGE, $this->createRule2Literals($package, $provider, $reason, $package));
-                }
-            }
         }
     }
 
@@ -327,12 +353,20 @@ class RuleSetGenerator
         $this->pool->setWhitelist($this->whitelistedMap);
 
         $this->addedMap = array();
+        $this->conflictAddedMap = array();
+        $this->addedPackages = array();
+        $this->addedPackagesByNames = array();
         foreach ($this->installedMap as $package) {
             $this->addRulesForPackage($package, $ignorePlatformReqs);
         }
 
         $this->addRulesForJobs($ignorePlatformReqs);
 
+        $this->addConflictRules();
+
+        // Remove references to packages
+        $this->addedPackages = $this->addedPackagesByNames = null;
+
         return $this->rules;
     }
 }