Composer gives .ini hints about missing extensions

src/Composer/DependencyResolver/SolverProblemsException.php

@@ -31,14 +31,23 @@ class SolverProblemsException extends \RuntimeException
     protected function createMessage()
     {
         $text = "\n";
+        $hasExtensionProblems = false;
         foreach ($this->problems as $i => $problem) {
             $text .= "  Problem ".($i + 1).$problem->getPrettyString($this->installedMap)."\n";
+
+            if (!$hasExtensionProblems && $this->hasExtensionProblems($problem->getReasons())) {
+                $hasExtensionProblems = true;
+            }
         }
 
         if (strpos($text, 'could not be found') || strpos($text, 'no matching package found')) {
             $text .= "\nPotential causes:\n - A typo in the package name\n - The package is not available in a stable-enough version according to your minimum-stability setting\n   see <https://groups.google.com/d/topic/composer-dev/_g3ASeIFlrc/discussion> for more details.\n\nRead <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.";
         }
 
+        if ($hasExtensionProblems) {
+            $text .= $this->createExtensionHint();
+        }
+
         return $text;
     }
 
@@ -46,4 +55,40 @@ class SolverProblemsException extends \RuntimeException
     {
         return $this->problems;
     }
+
+    private function createExtensionHint()
+    {
+        $paths = array();
+
+        if (($iniPath = php_ini_loaded_file()) !== false) {
+            $paths[] = $iniPath;
+        }
+
+        if (!defined('HHVM_VERSION') && $additionalIniPaths = php_ini_scanned_files()) {
+            $paths = array_merge($paths, array_map("trim", explode(",", $additionalIniPaths)));
+        }
+
+        if (count($paths) === 0) {
+            return '';
+        }
+
+        $text = "\n  Because of missing extensions, please verify whether they are enabled in those .ini files:\n    - ";
+        $text .= implode("\n    - ", $paths);
+        $text .= "\n  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.";
+
+        return $text;
+    }
+
+    private function hasExtensionProblems(array $reasonSets)
+    {
+        foreach ($reasonSets as $reasonSet) {
+            foreach($reasonSet as $reason) {
+                if (isset($reason["rule"]) && 0 === strpos($reason["rule"]->getRequiredPackage(), 'ext-')) {
+                    return true;
+                }
+            }
+        }
+
+        return false;
+    }
 }