Only compare branches as versions in the policy to sort packages, but not in the solver, fixes #1817

src/Composer/DependencyResolver/DefaultPolicy.php

@@ -39,7 +39,7 @@ class DefaultPolicy implements PolicyInterface
         $constraint = new VersionConstraint($operator, $b->getVersion());
         $version = new VersionConstraint('==', $a->getVersion());
 
-        return $constraint->matchSpecific($version);
+        return $constraint->matchSpecific($version, true);
     }
 
     public function findUpdatePackages(Pool $pool, array $installedMap, PackageInterface $package)

src/Composer/Package/LinkConstraint/VersionConstraint.php

@@ -44,12 +44,19 @@ class VersionConstraint extends SpecificConstraint
         $this->version = $version;
     }
 
-    public function versionCompare($a, $b, $operator)
+    public function versionCompare($a, $b, $operator, $compareBranches = false)
     {
-        if ('dev-' === substr($a, 0, 4) && 'dev-' === substr($b, 0, 4)) {
+        $aIsBranch = 'dev-' === substr($a, 0, 4);
+        $bIsBranch = 'dev-' === substr($b, 0, 4);
+        if ($aIsBranch && $bIsBranch) {
             return $operator == '==' && $a === $b;
         }
 
+        // when branches are not comparable, we make sure dev branches never match anything
+        if (!$compareBranches && ($aIsBranch || $bIsBranch)) {
+            return false;
+        }
+
         return version_compare($a, $b, $operator);
     }
 
@@ -57,7 +64,7 @@ class VersionConstraint extends SpecificConstraint
      *
      * @param VersionConstraint $provider
      */
-    public function matchSpecific(VersionConstraint $provider)
+    public function matchSpecific(VersionConstraint $provider, $compareBranches = false)
     {
         $noEqualOp = str_replace('=', '', $this->operator);
         $providerNoEqualOp = str_replace('=', '', $provider->operator);
@@ -71,7 +78,7 @@ class VersionConstraint extends SpecificConstraint
         // these kinds of comparisons always have a solution
         if ($isNonEqualOp || $isProviderNonEqualOp) {
             return !$isEqualOp && !$isProviderEqualOp
-                || $this->versionCompare($provider->version, $this->version, '!=');
+                || $this->versionCompare($provider->version, $this->version, '!=', $compareBranches);
         }
 
         // an example for the condition is <= 2.0 & < 1.0
@@ -80,7 +87,7 @@ class VersionConstraint extends SpecificConstraint
             return true;
         }
 
-        if ($this->versionCompare($provider->version, $this->version, $this->operator)) {
+        if ($this->versionCompare($provider->version, $this->version, $this->operator, $compareBranches)) {
             // special case, e.g. require >= 1.0 and provide < 1.0
             // 1.0 >= 1.0 but 1.0 is outside of the provided interval
             if ($provider->version == $this->version && $provider->operator == $providerNoEqualOp && $this->operator != $noEqualOp) {

tests/Composer/Test/DependencyResolver/DefaultPolicyTest.php

@@ -94,6 +94,20 @@ class DefaultPolicyTest extends TestCase
         $this->assertEquals($expected, $selected);
     }
 
+    public function testSelectNewestWithDevPicksNonDev()
+    {
+        $this->repo->addPackage($packageA1 = $this->getPackage('A', 'dev-foo'));
+        $this->repo->addPackage($packageA2 = $this->getPackage('A', '1.0.0'));
+        $this->pool->addRepository($this->repo);
+
+        $literals = array($packageA1->getId(), $packageA2->getId());
+        $expected = array($packageA2->getId());
+
+        $selected = $this->policy->selectPreferedPackages($this->pool, array(), $literals);
+
+        $this->assertEquals($expected, $selected);
+    }
+
     public function testSelectNewestOverInstalled()
     {
         $this->repo->addPackage($packageA = $this->getPackage('A', '2.0'));

tests/Composer/Test/Package/LinkConstraint/VersionConstraintTest.php

@@ -72,6 +72,8 @@ class VersionConstraintTest extends \PHPUnit_Framework_TestCase
             array('==', 'dev-foo-bist', '==', 'dev-foo-aist'),
             array('<=', 'dev-foo-bist', '>=', 'dev-foo-aist'),
             array('>=', 'dev-foo-bist', '<', 'dev-foo-aist'),
+            array('<',  '0.12', '==', 'dev-foo'), // branches are not comparable
+            array('>',  '0.12', '==', 'dev-foo'), // branches are not comparable
         );
     }
 
@@ -85,4 +87,19 @@ class VersionConstraintTest extends \PHPUnit_Framework_TestCase
 
         $this->assertFalse($versionRequire->matches($versionProvide));
     }
+
+    public function testComparableBranches()
+    {
+        $versionRequire = new VersionConstraint('>', '0.12');
+        $versionProvide = new VersionConstraint('==', 'dev-foo');
+
+        $this->assertFalse($versionRequire->matches($versionProvide));
+        $this->assertFalse($versionRequire->matchSpecific($versionProvide, true));
+
+        $versionRequire = new VersionConstraint('<', '0.12');
+        $versionProvide = new VersionConstraint('==', 'dev-foo');
+
+        $this->assertFalse($versionRequire->matches($versionProvide));
+        $this->assertTrue($versionRequire->matchSpecific($versionProvide, true));
+    }
 }