Add support for detecting packages not matching only due to minimum stability

src/Composer/DependencyResolver/Problem.php

@@ -276,27 +276,19 @@ class Problem
 
         // check if the package is found when bypassing stability checks
         if ($packages = $repositorySet->findPackages($packageName, $constraint, RepositorySet::ALLOW_UNACCEPTABLE_STABILITIES)) {
+            // we must first verify if a valid package would be found in a lower priority repository
+            if ($allReposPackages = $repositorySet->findPackages($packageName, $constraint, RepositorySet::ALLOW_SHADOWED_REPOSITORIES)) {
+                return self::computeCheckForLowerPrioRepo($isVerbose, $packageName, $constraint, $packages, $allReposPackages, 'minimum-stability');
+            }
+
             return array("- Root composer.json requires $packageName".self::constraintToText($constraint) . ', ', 'found '.self::getPackageList($packages, $isVerbose).' but '.(self::hasMultipleNames($packages) ? 'these do' : 'it does').' not match your minimum-stability.');
         }
 
-        // check if the package is found when bypassing the constraint check and stability checks
+        // check if the package is found when bypassing the constraint and stability checks
         if ($packages = $repositorySet->findPackages($packageName, null, RepositorySet::ALLOW_UNACCEPTABLE_STABILITIES)) {
             // we must first verify if a valid package would be found in a lower priority repository
             if ($allReposPackages = $repositorySet->findPackages($packageName, $constraint, RepositorySet::ALLOW_SHADOWED_REPOSITORIES)) {
-                $higherRepoPackages = $repositorySet->findPackages($packageName, null, RepositorySet::ALLOW_UNACCEPTABLE_STABILITIES);
-                $nextRepoPackages = array();
-                $nextRepo = null;
-
-                foreach ($allReposPackages as $package) {
-                    if ($nextRepo === null || $nextRepo === $package->getRepository()) {
-                        $nextRepoPackages[] = $package;
-                        $nextRepo = $package->getRepository();
-                    } else {
-                        break;
-                    }
-                }
-
-                return array("- Root composer.json requires $packageName".self::constraintToText($constraint) . ', it is ', 'satisfiable by '.self::getPackageList($nextRepoPackages, $isVerbose).' from '.$nextRepo->getRepoName().' but '.self::getPackageList($higherRepoPackages, $isVerbose).' from '.reset($higherRepoPackages)->getRepository()->getRepoName().' has higher repository priority. The packages with higher priority do not match your constraint and are therefore not installable. See https://getcomposer.org/repoprio for details and assistance.');
+                return self::computeCheckForLowerPrioRepo($isVerbose, $packageName, $constraint, $packages, $allReposPackages, 'constraint');
             }
 
             return array("- Root composer.json requires $packageName".self::constraintToText($constraint) . ', ', 'found '.self::getPackageList($packages, $isVerbose).' but '.(self::hasMultipleNames($packages) ? 'these do' : 'it does').' not match the constraint.');
@@ -396,6 +388,24 @@ class Problem
         return false;
     }
 
+    private static function computeCheckForLowerPrioRepo($isVerbose, $packageName, $constraint, array $higherRepoPackages, array $allReposPackages, $reason)
+    {
+        $nextRepoPackages = array();
+        $nextRepo = null;
+
+        foreach ($allReposPackages as $package) {
+            if ($nextRepo === null || $nextRepo === $package->getRepository()) {
+                $nextRepoPackages[] = $package;
+                $nextRepo = $package->getRepository();
+            } else {
+                break;
+            }
+        }
+
+        return array("- Root composer.json requires $packageName".self::constraintToText($constraint) . ', it is ', 'satisfiable by '.self::getPackageList($nextRepoPackages, $isVerbose).' from '.$nextRepo->getRepoName().' but '.self::getPackageList($higherRepoPackages, $isVerbose).' from '.reset($higherRepoPackages)->getRepository()->getRepoName().' has higher repository priority. The packages with higher priority do not match your '.$reason.' and are therefore not installable. See https://getcomposer.org/repoprio for details and assistance.');
+
+    }
+
     /**
      * Turns a constraint into text usable in a sentence describing a request
      *

tests/Composer/Test/Fixtures/installer/repositories-priorities5.test

@@ -0,0 +1,35 @@
+--TEST--
+Packages found in a higher priority repository take precedence even if they are not found in the requested version case #3
+--COMPOSER--
+{
+    "repositories": [
+        {
+            "type": "package",
+            "package": [
+                { "name": "foo/a", "version": "2.0.0-dev" }
+            ]
+        },
+        {
+            "type": "package",
+            "package": [
+                { "name": "foo/a", "version": "2.0.0" }
+            ]
+        }
+    ],
+    "require": {
+        "foo/a": "2.*"
+    }
+}
+--RUN--
+update
+--EXPECT-OUTPUT--
+Loading composer repositories with package information
+Updating dependencies
+Your requirements could not be resolved to an installable set of packages.
+
+  Problem 1
+    - Root composer.json requires foo/a 2.*, it is satisfiable by foo/a[2.0.0] from package repo (defining 1 package) but foo/a[2.0.0-dev] from package repo (defining 1 package) has higher repository priority. The packages with higher priority do not match your minimum-stability and are therefore not installable. See https://getcomposer.org/repoprio for details and assistance.
+
+--EXPECT--
+--EXPECT-EXIT-CODE--
+2