Improve error reporting some more, fixes #4310

src/Composer/DependencyResolver/Problem.php

@@ -130,11 +130,11 @@ class Problem
                 }
 
                 if ($providers = $this->pool->whatProvides($job['packageName'], $job['constraint'], true, true)) {
-                    return "\n    - The requested package ".$job['packageName'].$this->constraintToText($job['constraint']).' is satisfiable by '.$this->getPackageList($providers).' but those are rejected by your minimum-stability.';
+                    return "\n    - The requested package ".$job['packageName'].$this->constraintToText($job['constraint']).' is satisfiable by '.$this->getPackageList($providers).' but these conflict with your requirements or minimum-stability.';
                 }
 
                 if ($providers = $this->pool->whatProvides($job['packageName'], null, true, true)) {
-                    return "\n    - The requested package ".$job['packageName'].$this->constraintToText($job['constraint']).' exists as '.$this->getPackageList($providers).' but those are rejected by your constraint.';
+                    return "\n    - The requested package ".$job['packageName'].$this->constraintToText($job['constraint']).' exists as '.$this->getPackageList($providers).' but these are rejected by your constraint.';
                 }
 
                 return "\n    - The requested package ".$job['packageName'].' could not be found in any version, there may be a typo in the package name.';

src/Composer/DependencyResolver/Rule.php

@@ -241,7 +241,7 @@ class Rule
                         return $text . ' -> the requested linked library '.$lib.' has the wrong version installed or is missing from your system, make sure to have the extension providing it.';
                     } else {
                         if ($providers = $pool->whatProvides($targetName, $this->reasonData->getConstraint(), true, true)) {
-                            return $text . ' -> satisfiable by ' . $this->formatPackagesUnique($pool, $providers) .' but these conflict with your requirements or minimum-stability';
+                            return $text . ' -> satisfiable by ' . $this->formatPackagesUnique($pool, $providers) .' but these conflict with your requirements or minimum-stability.';
                         }
 
                         return $text . ' -> no matching package found.';

src/Composer/Installer.php

@@ -448,6 +448,7 @@ class Installer
                 $candidates = array();
                 foreach ($links as $link) {
                     $candidates[$link->getTarget()] = true;
+                    $rootRequires[$link->getTarget()] = $link;
                 }
                 foreach ($localRepo->getPackages() as $package) {
                     $candidates[$package->getName()] = true;
@@ -459,6 +460,9 @@ class Installer
                         if ($curPackage->getName() === $candidate) {
                             if (!$this->isUpdateable($curPackage) && !isset($removedUnstablePackages[$curPackage->getName()])) {
                                 $constraint = new Constraint('=', $curPackage->getVersion());
+                                $description = $this->locker->isLocked() ? '(locked at' : '(installed at';
+                                $requiredAt = isset($rootRequires[$candidate]) ? ', required as ' . $rootRequires[$candidate]->getPrettyConstraint() : '';
+                                $constraint->setPrettyString($description . ' ' . $curPackage->getPrettyVersion() . $requiredAt . ')');
                                 $request->install($curPackage->getName(), $constraint);
                             }
                             break;

tests/Composer/Test/Fixtures/installer/solver-problems.test

@@ -10,7 +10,9 @@ Test the error output of solver problems.
                 { "name": "unstable/package", "version": "1.0.0" },
                 { "name": "requirer", "version": "1.0.0", "require": {"dependency": "1.0.0" } },
                 { "name": "dependency", "version": "2.0.0" },
-                { "name": "dependency", "version": "1.0.0" }
+                { "name": "dependency", "version": "1.0.0" },
+                { "name": "stable-requiree-excluded", "version": "1.0.1" },
+                { "name": "stable-requiree-excluded", "version": "1.0.0" }
             ]
         }
     ],
@@ -18,12 +20,18 @@ Test the error output of solver problems.
         "unstable/package": "2.*",
         "bogus": "1.*",
         "requirer": "1.*",
-        "dependency": "2.*"
+        "dependency": "2.*",
+        "stable-requiree-excluded": "1.0.1"
     }
 }
 
+--INSTALLED--
+[
+    { "name": "stable-requiree-excluded", "version": "1.0.0" }
+]
+
 --RUN--
-install
+update unstable/package requirer dependency
 
 --EXPECT-EXIT-CODE--
 2
@@ -34,12 +42,14 @@ Updating dependencies (including require-dev)
 Your requirements could not be resolved to an installable set of packages.
 
   Problem 1
-    - The requested package unstable/package 2.* exists as unstable/package[1.0.0] but those are rejected by your constraint.
+    - The requested package unstable/package 2.* exists as unstable/package[1.0.0] but these are rejected by your constraint.
   Problem 2
     - The requested package bogus could not be found in any version, there may be a typo in the package name.
   Problem 3
+    - The requested package stable-requiree-excluded (installed at 1.0.0, required as 1.0.1) is satisfiable by stable-requiree-excluded[1.0.0] but these conflict with your requirements or minimum-stability.
+  Problem 4
     - Installation request for requirer 1.* -> satisfiable by requirer[1.0.0].
-    - requirer 1.0.0 requires dependency 1.0.0 -> satisfiable by dependency[1.0.0] but these conflict with your requirements or minimum-stability
+    - requirer 1.0.0 requires dependency 1.0.0 -> satisfiable by dependency[1.0.0] but these conflict with your requirements or minimum-stability.
 
 Potential causes:
  - A typo in the package name