Debug info improvements

src/Composer/Command/RequireCommand.php

@@ -190,7 +190,7 @@ EOT
             );
         } catch (\Exception $e) {
             if ($this->newlyCreated) {
-                throw new \RuntimeException('No composer.json present in the current directory, this may be the cause of the following exception.', 0, $e);
+                throw new \RuntimeException('No composer.json present in the current directory ('.$this->file.'), this may be the cause of the following exception.', 0, $e);
             }
 
             throw $e;

src/Composer/Factory.php

@@ -315,7 +315,7 @@ class Factory
         $config = static::createConfig($io, $cwd);
         $config->merge($localConfig);
         if (isset($composerFile)) {
-            $io->writeError('Loading config file ' . $composerFile, true, IOInterface::DEBUG);
+            $io->writeError('Loading config file ' . $composerFile .' ('.realpath($composerFile).')', true, IOInterface::DEBUG);
             $config->setConfigSource(new JsonConfigSource(new JsonFile(realpath($composerFile), null, $io)));
 
             $localAuthFile = new JsonFile(dirname(realpath($composerFile)) . '/auth.json', null, $io);

src/Composer/Json/JsonFile.php

@@ -90,7 +90,12 @@ class JsonFile
                 $json = $this->httpDownloader->get($this->path)->getBody();
             } else {
                 if ($this->io && $this->io->isDebug()) {
-                    $this->io->writeError('Reading ' . $this->path);
+                    $realpathInfo = '';
+                    $realpath = realpath($this->path);
+                    if (false !== $realpath && $realpath !== $this->path) {
+                         $realpathInfo = ' (' . $realpath . ')';
+                    }
+                    $this->io->writeError('Reading ' . $this->path . $realpathInfo);
                 }
                 $json = file_get_contents($this->path);
             }