Whitelist packages with names matching those specified before generating rules

Addresses #2690 doesn't do any performance optimisations yet which we
could do now

src/Composer/DependencyResolver/DefaultPolicy.php

@@ -42,11 +42,11 @@ class DefaultPolicy implements PolicyInterface
         return $constraint->matchSpecific($version, true);
     }
 
-    public function findUpdatePackages(Pool $pool, array $installedMap, PackageInterface $package)
+    public function findUpdatePackages(Pool $pool, array $installedMap, PackageInterface $package, $mustMatchName = false)
     {
         $packages = array();
 
-        foreach ($pool->whatProvides($package->getName()) as $candidate) {
+        foreach ($pool->whatProvides($package->getName(), null, $mustMatchName) as $candidate) {
             if ($candidate !== $package) {
                 $packages[] = $candidate;
             }

src/Composer/DependencyResolver/Pool.php

@@ -50,6 +50,7 @@ class Pool
     protected $versionParser;
     protected $providerCache = array();
     protected $filterRequires;
+    protected $whitelist = null;
     protected $id = 1;
 
     public function __construct($minimumStability = 'stable', array $stabilityFlags = array(), array $filterRequires = array())
@@ -66,6 +67,11 @@ class Pool
         $this->filterRequires = $filterRequires;
     }
 
+    public function setWhitelist($whitelist)
+    {
+        $this->whitelist = $whitelist;
+    }
+
     /**
      * Adds a repository and its packages to this package pool
      *
@@ -223,21 +229,24 @@ class Pool
      * @param string                  $name       The package name to be searched for
      * @param LinkConstraintInterface $constraint A constraint that all returned
      *                                            packages must match or null to return all
+     * @param bool                    $mustMatchName Whether the name of returned packages
+     *                                            must match the given name
      * @return array A set of packages
      */
-    public function whatProvides($name, LinkConstraintInterface $constraint = null)
+    public function whatProvides($name, LinkConstraintInterface $constraint = null, $mustMatchName = false)
     {
-        if (isset($this->providerCache[$name][(string) $constraint])) {
-            return $this->providerCache[$name][(string) $constraint];
+        $key = ((string) (int) $mustMatchName).((string) $constraint);
+        if (isset($this->providerCache[$name][$key])) {
+            return $this->providerCache[$name][$key];
         }
 
-        return $this->providerCache[$name][(string) $constraint] = $this->computeWhatProvides($name, $constraint);
+        return $this->providerCache[$name][$key] = $this->computeWhatProvides($name, $constraint, $mustMatchName);
     }
 
     /**
      * @see whatProvides
      */
-    private function computeWhatProvides($name, $constraint)
+    private function computeWhatProvides($name, $constraint, $mustMatchName = false)
     {
         $candidates = array();
 
@@ -259,6 +268,9 @@ class Pool
         $nameMatch = false;
 
         foreach ($candidates as $candidate) {
+            if ($this->whitelist !== null && !isset($this->whitelist[$candidate->getId()])) {
+                continue;
+            }
             switch ($this->match($candidate, $name, $constraint)) {
                 case self::MATCH_NONE:
                     break;
@@ -289,7 +301,7 @@ class Pool
         }
 
         // if a package with the required name exists, we ignore providers
-        if ($nameMatch) {
+        if ($nameMatch || $mustMatchName) {
             return $matches;
         }
 

src/Composer/DependencyResolver/Request.php

@@ -46,7 +46,7 @@ class Request
     protected function addJob($packageName, $cmd, LinkConstraintInterface $constraint = null)
     {
         $packageName = strtolower($packageName);
-        $packages = $this->pool->whatProvides($packageName, $constraint);
+        $packages = $this->pool->whatProvides($packageName, $constraint, true);
 
         $this->jobs[] = array(
             'packages' => $packages,

src/Composer/DependencyResolver/RuleSetGenerator.php

@@ -25,6 +25,8 @@ class RuleSetGenerator
     protected $rules;
     protected $jobs;
     protected $installedMap;
+    protected $whitelistedMap;
+    protected $addedMap;
 
     public function __construct(PolicyInterface $policy, Pool $pool)
     {
@@ -141,6 +143,41 @@ class RuleSetGenerator
         $this->rules->add($newRule, $type);
     }
 
+    protected function whitelistFromPackage(PackageInterface $package)
+    {
+        $workQueue = new \SplQueue;
+        $workQueue->enqueue($package);
+
+        while (!$workQueue->isEmpty()) {
+            $package = $workQueue->dequeue();
+            if (isset($this->whitelistedMap[$package->getId()])) {
+                continue;
+            }
+
+            $this->whitelistedMap[$package->getId()] = true;
+
+            foreach ($package->getRequires() as $link) {
+                $possibleRequires = $this->pool->whatProvides($link->getTarget(), $link->getConstraint(), true);
+
+                foreach ($possibleRequires as $require) {
+                    $workQueue->enqueue($require);
+                }
+            }
+
+            $obsoleteProviders = $this->pool->whatProvides($package->getName(), null, true);
+
+            foreach ($obsoleteProviders as $provider) {
+                if ($provider === $package) {
+                    continue;
+                }
+
+                if (($package instanceof AliasPackage) && $package->getAliasOf() === $provider) {
+                    $workQueue->enqueue($provider);
+                }
+            }
+        }
+    }
+
     protected function addRulesForPackage(PackageInterface $package)
     {
         $workQueue = new \SplQueue;
@@ -236,6 +273,30 @@ class RuleSetGenerator
         }
     }
 
+    private function whitelistFromUpdatePackages(PackageInterface $package)
+    {
+        $updates = $this->policy->findUpdatePackages($this->pool, $this->installedMap, $package, true);
+
+        foreach ($updates as $update) {
+            $this->whitelistFromPackage($update);
+        }
+    }
+
+    protected function whitelistFromJobs()
+    {
+        foreach ($this->jobs as $job) {
+            switch ($job['cmd']) {
+                case 'install':
+                    if ($job['packages']) {
+                        foreach ($job['packages'] as $package) {
+                            $this->whitelistFromPackage($package);
+                        }
+                    }
+                    break;
+            }
+        }
+    }
+
     protected function addRulesForJobs()
     {
         foreach ($this->jobs as $job) {
@@ -270,6 +331,16 @@ class RuleSetGenerator
         $this->rules = new RuleSet;
         $this->installedMap = $installedMap;
 
+        $this->whitelistedNames = array();
+        foreach ($this->installedMap as $package) {
+            $this->whitelistFromPackage($package);
+            $this->whitelistFromUpdatePackages($package);
+        }
+        $this->whitelistFromJobs();
+
+        $this->pool->setWhitelist($this->whitelistedMap);
+
+        $this->addedMap = array();
         foreach ($this->installedMap as $package) {
             $this->addRulesForPackage($package);
             $this->addRulesForUpdatePackages($package);

tests/Composer/Test/DependencyResolver/SolverTest.php

@@ -441,10 +441,9 @@ class SolverTest extends TestCase
 
         $this->request->install('A');
 
-        $this->checkSolverResult(array(
-            array('job' => 'install', 'package' => $packageQ),
-            array('job' => 'install', 'package' => $packageA),
-        ));
+        // must explicitly pick the provider, so error in this case
+        $this->setExpectedException('Composer\DependencyResolver\SolverProblemsException');
+        $this->solver->solve($this->request);
     }
 
     public function testSkipReplacerOfExistingPackage()
@@ -574,11 +573,12 @@ class SolverTest extends TestCase
         $this->reposComplete();
 
         $this->request->install('A');
+        $this->request->install('C');
 
         $this->checkSolverResult(array(
-            array('job' => 'install', 'package' => $packageB),
             array('job' => 'install', 'package' => $packageA),
             array('job' => 'install', 'package' => $packageC),
+            array('job' => 'install', 'package' => $packageB),
         ));
     }
 

tests/Composer/Test/Fixtures/installer/provide-priorities.test

@@ -1,34 +0,0 @@
---TEST--
-Provide only applies when no existing package has the given name
---COMPOSER--
-{
-    "repositories": [
-        {
-            "type": "package",
-            "package": [
-                { "name": "higher-prio-hijacker", "version": "1.1.0", "provide": { "package": "1.0.0" } },
-                { "name": "provider2", "version": "1.1.0", "provide": { "package2": "1.0.0" } }
-            ]
-        },
-        {
-            "type": "package",
-            "package": [
-                { "name": "package", "version": "0.9.0" },
-                { "name": "package", "version": "1.0.0" },
-                { "name": "hijacker", "version": "1.1.0", "provide": { "package": "1.0.0" } },
-                { "name": "provider3", "version": "1.1.0", "provide": { "package3": "1.0.0" } }
-            ]
-        }
-    ],
-    "require": {
-        "package": "1.*",
-        "package2": "1.*",
-        "provider3": "1.1.0"
-    }
-}
---RUN--
-install
---EXPECT--
-Installing package (1.0.0)
-Installing provider2 (1.1.0)
-Installing provider3 (1.1.0)