bug #23909 [Console] Initialize lazily to render exceptions properly (nicolas-grekas)

This PR was merged into the 2.7 branch.

Discussion
----------

[Console] Initialize lazily to render exceptions properly

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

When an exception occurs in the constructor of an `Application`, exception handling is not yet set up.
This typically happens when the container cannot be build for some reason, where calling `$this->add()` builds the container and fails.

This PR makes initialization lazy so that it happens later on, when exception handling might be OK.

Before:
![before](https://user-images.githubusercontent.com/243674/29403397-7f7a1fce-8338-11e7-8e62-b6302ff0a65e.png)

After:
![after](https://user-images.githubusercontent.com/243674/29403403-83f7b5c0-8338-11e7-9a22-0c5ee702f1ff.png)

Commits
-------

62174fd [Console] Initialize lazily to render exceptions properly

src/Symfony/Component/Console/Application.php

@@ -72,6 +72,7 @@ class Application
     private $dispatcher;
     private $terminalDimensions;
     private $defaultCommand;
+    private $initialized;
 
     /**
      * Constructor.
@@ -84,12 +85,6 @@ class Application
         $this->name = $name;
         $this->version = $version;
         $this->defaultCommand = 'list';
-        $this->helperSet = $this->getDefaultHelperSet();
-        $this->definition = $this->getDefaultInputDefinition();
-
-        foreach ($this->getDefaultCommands() as $command) {
-            $this->add($command);
-        }
     }
 
     public function setDispatcher(EventDispatcherInterface $dispatcher)
@@ -189,10 +184,11 @@ class Application
 
         if (!$name) {
             $name = $this->defaultCommand;
-            $this->definition->setArguments(array_merge(
-                $this->definition->getArguments(),
+            $definition = $this->getDefinition();
+            $definition->setArguments(array_merge(
+                $definition->getArguments(),
                 array(
-                    'command' => new InputArgument('command', InputArgument::OPTIONAL, $this->definition->getArgument('command')->getDescription(), $name),
+                    'command' => new InputArgument('command', InputArgument::OPTIONAL, $definition->getArgument('command')->getDescription(), $name),
                 )
             ));
         }
@@ -225,6 +221,10 @@ class Application
      */
     public function getHelperSet()
     {
+        if (!$this->helperSet) {
+            $this->helperSet = $this->getDefaultHelperSet();
+        }
+
         return $this->helperSet;
     }
 
@@ -245,6 +245,10 @@ class Application
      */
     public function getDefinition()
     {
+        if (!$this->definition) {
+            $this->definition = $this->getDefaultInputDefinition();
+        }
+
         return $this->definition;
     }
 
@@ -374,6 +378,8 @@ class Application
      */
     public function add(Command $command)
     {
+        $this->init();
+
         $command->setApplication($this);
 
         if (!$command->isEnabled()) {
@@ -406,6 +412,8 @@ class Application
      */
     public function get($name)
     {
+        $this->init();
+
         if (!isset($this->commands[$name])) {
             throw new \InvalidArgumentException(sprintf('The command "%s" does not exist.', $name));
         }
@@ -433,6 +441,8 @@ class Application
      */
     public function has($name)
     {
+        $this->init();
+
         return isset($this->commands[$name]);
     }
 
@@ -510,6 +520,8 @@ class Application
      */
     public function find($name)
     {
+        $this->init();
+
         $allCommands = array_keys($this->commands);
         $expr = preg_replace_callback('{([^:]+|)}', function ($matches) { return preg_quote($matches[1]).'[^:]*'; }, $name);
         $commands = preg_grep('{^'.$expr.'}', $allCommands);
@@ -565,6 +577,8 @@ class Application
      */
     public function all($namespace = null)
     {
+        $this->init();
+
         if (null === $namespace) {
             return $this->commands;
         }
@@ -1151,4 +1165,16 @@ class Application
 
         return $namespaces;
     }
+
+    private function init()
+    {
+        if ($this->initialized) {
+            return;
+        }
+        $this->initialized = true;
+
+        foreach ($this->getDefaultCommands() as $command) {
+            $this->add($command);
+        }
+    }
 }