feature #27476 [Config] deprecate tree builders without root nodes (x…

…abbuh)

This PR was merged into the 4.2-dev branch.

Discussion
----------

[Config] deprecate tree builders without root nodes

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

While reviewing #27472 I wondered if we really need support config trees without a root node. If we did not support it, users wouldn't create pseudo configuration classes when they were actually not needed.

Commits
-------

c2ce153 deprecate tree builders without root nodes

UPGRADE-4.2.md

@@ -25,6 +25,12 @@ Form
       {{ form_widget(field) }}
    {% endfor %}
    ```
+
+Config
+------
+
+ * Deprecated constructing a `TreeBuilder` without passing root node information.
+
 Security
 --------
 

UPGRADE-5.0.md

@@ -9,6 +9,7 @@ Cache
 Config
 ------
 
+ * Dropped support for constructing a `TreeBuilder` without passing root node information.
  * Added the `getChildNodeDefinitions()` method to `ParentNodeDefinitionInterface`.
  * The `Processor` class has been made final
 

src/Symfony/Bundle/DebugBundle/DependencyInjection/Configuration.php

@@ -26,10 +26,9 @@ class Configuration implements ConfigurationInterface
      */
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $rootNode = $treeBuilder->root('debug');
+        $treeBuilder = new TreeBuilder('debug');
 
-        $rootNode
+        $treeBuilder->getRootNode()
             ->children()
                 ->integerNode('max_items')
                     ->info('Max number of displayed items past the first level, -1 means no limit')

src/Symfony/Bundle/DebugBundle/composer.json

@@ -23,11 +23,12 @@
         "symfony/var-dumper": "^4.1.1"
     },
     "require-dev": {
-        "symfony/config": "~3.4|~4.0",
+        "symfony/config": "~4.2",
         "symfony/dependency-injection": "~3.4|~4.0",
         "symfony/web-profiler-bundle": "~3.4|~4.0"
     },
     "conflict": {
+        "symfony/config": "<4.2",
         "symfony/dependency-injection": "<3.4"
     },
     "suggest": {

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php

@@ -54,8 +54,8 @@ public function __construct(bool $debug)
      */
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $rootNode = $treeBuilder->root('framework');
+        $treeBuilder = new TreeBuilder('framework');
+        $rootNode = $treeBuilder->getRootNode();
 
         $rootNode
             ->beforeNormalization()

src/Symfony/Bundle/FrameworkBundle/Tests/Functional/Bundle/TestBundle/DependencyInjection/Configuration.php

@@ -25,11 +25,10 @@ public function __construct($customConfig = null)
 
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $rootNode = $treeBuilder->root('test');
+        $treeBuilder = new TreeBuilder('test');
 
         if ($this->customConfig) {
-            $this->customConfig->addConfiguration($rootNode);
+            $this->customConfig->addConfiguration($treeBuilder->getRootNode());
         }
 
         return $treeBuilder;

src/Symfony/Bundle/FrameworkBundle/composer.json

@@ -20,7 +20,7 @@
         "ext-xml": "*",
         "symfony/cache": "~3.4|~4.0",
         "symfony/dependency-injection": "^4.1.1",
-        "symfony/config": "~3.4|~4.0",
+        "symfony/config": "~4.2",
         "symfony/event-dispatcher": "^4.1",
         "symfony/http-foundation": "^4.1",
         "symfony/http-kernel": "^4.1",

src/Symfony/Bundle/SecurityBundle/DependencyInjection/MainConfiguration.php

@@ -41,8 +41,8 @@ public function __construct(array $factories, array $userProviderFactories)
      */
     public function getConfigTreeBuilder()
     {
-        $tb = new TreeBuilder();
-        $rootNode = $tb->root('security');
+        $tb = new TreeBuilder('security');
+        $rootNode = $tb->getRootNode();
 
         $rootNode
             ->beforeNormalization()

src/Symfony/Bundle/SecurityBundle/composer.json

@@ -18,6 +18,7 @@
     "require": {
         "php": "^7.1.3",
         "ext-xml": "*",
+        "symfony/config": "^4.2",
         "symfony/security": "~4.2",
         "symfony/dependency-injection": "^3.4.3|^4.0.3",
         "symfony/http-kernel": "^4.1"

src/Symfony/Bundle/TwigBundle/DependencyInjection/Configuration.php

@@ -29,8 +29,8 @@ class Configuration implements ConfigurationInterface
      */
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $rootNode = $treeBuilder->root('twig');
+        $treeBuilder = new TreeBuilder('twig');
+        $rootNode = $treeBuilder->getRootNode();
 
         $rootNode
             ->children()

src/Symfony/Bundle/TwigBundle/composer.json

@@ -17,7 +17,7 @@
     ],
     "require": {
         "php": "^7.1.3",
-        "symfony/config": "~3.4|~4.0",
+        "symfony/config": "~4.2",
         "symfony/twig-bridge": "^3.4.3|^4.0.3",
         "symfony/http-foundation": "~4.1",
         "symfony/http-kernel": "~4.1",

src/Symfony/Bundle/WebProfilerBundle/DependencyInjection/Configuration.php

@@ -31,10 +31,9 @@ class Configuration implements ConfigurationInterface
      */
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $rootNode = $treeBuilder->root('web_profiler');
+        $treeBuilder = new TreeBuilder('web_profiler');
 
-        $rootNode
+        $treeBuilder->getRootNode()
             ->children()
                 ->booleanNode('toolbar')->defaultFalse()->end()
                 ->booleanNode('intercept_redirects')->defaultFalse()->end()

src/Symfony/Bundle/WebProfilerBundle/composer.json

@@ -17,20 +17,19 @@
     ],
     "require": {
         "php": "^7.1.3",
+        "symfony/config": "^4.2",
         "symfony/http-kernel": "~4.1",
         "symfony/routing": "~3.4|~4.0",
         "symfony/twig-bundle": "^3.4.3|^4.0.3",
         "symfony/var-dumper": "~3.4|~4.0",
         "twig/twig": "~1.34|~2.4"
     },
     "require-dev": {
-        "symfony/config": "~3.4|~4.0",
         "symfony/console": "~3.4|~4.0",
         "symfony/dependency-injection": "~3.4|~4.0",
         "symfony/stopwatch": "~3.4|~4.0"
     },
     "conflict": {
-        "symfony/config": "<3.4",
         "symfony/dependency-injection": "<3.4",
         "symfony/event-dispatcher": "<3.4",
         "symfony/var-dumper": "<3.4"

src/Symfony/Component/Config/CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+4.2.0
+-----
+
+ * deprecated constructing a `TreeBuilder` without passing root node information
+
 4.1.0
 -----
 

src/Symfony/Component/Config/Definition/Builder/TreeBuilder.php

@@ -24,6 +24,15 @@ class TreeBuilder implements NodeParentInterface
     protected $tree;
     protected $root;
 
+    public function __construct(string $name = null, string $type = 'array', NodeBuilder $builder = null)
+    {
+        if (null === $name) {
+            @trigger_error('A tree builder without a root node is deprecated since Symfony 4.2 and will not be supported anymore in 5.0.', E_USER_DEPRECATED);
+        } else {
+            $this->root($name, $type, $builder);
+        }
+    }
+
     /**
      * Creates the root node.
      *
@@ -42,6 +51,15 @@ public function root($name, $type = 'array', NodeBuilder $builder = null)
         return $this->root = $builder->node($name, $type)->setParent($this);
     }
 
+    public function getRootNode(): NodeDefinition
+    {
+        if (null === $this->root) {
+            throw new \RuntimeException(sprintf('Calling %s() before creating the root node is not supported, migrate to the new constructor signature instead.', __METHOD__));
+        }
+
+        return $this->root;
+    }
+
     /**
      * Builds the tree.
      *

src/Symfony/Component/Config/Tests/Definition/Builder/ExprBuilderTest.php

@@ -212,10 +212,10 @@ public function testEndThenPartNotSpecified()
      */
     protected function getTestBuilder()
     {
-        $builder = new TreeBuilder();
+        $builder = new TreeBuilder('test');
 
         return $builder
-            ->root('test')
+            ->getRootNode()
             ->children()
             ->variableNode('key')
             ->validate()

src/Symfony/Component/Config/Tests/Definition/Builder/TreeBuilderTest.php

@@ -19,10 +19,9 @@ class TreeBuilderTest extends TestCase
 {
     public function testUsingACustomNodeBuilder()
     {
-        $builder = new TreeBuilder();
-        $root = $builder->root('custom', 'array', new CustomNodeBuilder());
+        $builder = new TreeBuilder('custom', 'array', new CustomNodeBuilder());
 
-        $nodeBuilder = $root->children();
+        $nodeBuilder = $builder->getRootNode()->children();
 
         $this->assertInstanceOf('Symfony\Component\Config\Tests\Fixtures\Builder\NodeBuilder', $nodeBuilder);
 
@@ -33,49 +32,46 @@ public function testUsingACustomNodeBuilder()
 
     public function testOverrideABuiltInNodeType()
     {
-        $builder = new TreeBuilder();
-        $root = $builder->root('override', 'array', new CustomNodeBuilder());
+        $builder = new TreeBuilder('override', 'array', new CustomNodeBuilder());
 
-        $definition = $root->children()->variableNode('variable');
+        $definition = $builder->getRootNode()->children()->variableNode('variable');
 
         $this->assertInstanceOf('Symfony\Component\Config\Tests\Fixtures\Builder\VariableNodeDefinition', $definition);
     }
 
     public function testAddANodeType()
     {
-        $builder = new TreeBuilder();
-        $root = $builder->root('override', 'array', new CustomNodeBuilder());
+        $builder = new TreeBuilder('override', 'array', new CustomNodeBuilder());
 
-        $definition = $root->children()->barNode('variable');
+        $definition = $builder->getRootNode()->children()->barNode('variable');
 
         $this->assertInstanceOf('Symfony\Component\Config\Tests\Fixtures\Builder\BarNodeDefinition', $definition);
     }
 
     public function testCreateABuiltInNodeTypeWithACustomNodeBuilder()
     {
-        $builder = new TreeBuilder();
-        $root = $builder->root('builtin', 'array', new CustomNodeBuilder());
+        $builder = new TreeBuilder('builtin', 'array', new CustomNodeBuilder());
 
-        $definition = $root->children()->booleanNode('boolean');
+        $definition = $builder->getRootNode()->children()->booleanNode('boolean');
 
         $this->assertInstanceOf('Symfony\Component\Config\Definition\Builder\BooleanNodeDefinition', $definition);
     }
 
     public function testPrototypedArrayNodeUseTheCustomNodeBuilder()
     {
-        $builder = new TreeBuilder();
-        $root = $builder->root('override', 'array', new CustomNodeBuilder());
+        $builder = new TreeBuilder('override', 'array', new CustomNodeBuilder());
 
+        $root = $builder->getRootNode();
         $root->prototype('bar')->end();
 
         $this->assertInstanceOf('Symfony\Component\Config\Tests\Fixtures\BarNode', $root->getNode(true)->getPrototype());
     }
 
     public function testAnExtendedNodeBuilderGetsPropagatedToTheChildren()
     {
-        $builder = new TreeBuilder();
+        $builder = new TreeBuilder('propagation');
 
-        $builder->root('propagation')
+        $builder->getRootNode()
             ->children()
                 ->setNodeClass('extended', 'Symfony\Component\Config\Definition\Builder\BooleanNodeDefinition')
                 ->node('foo', 'extended')->end()
@@ -99,9 +95,9 @@ public function testAnExtendedNodeBuilderGetsPropagatedToTheChildren()
 
     public function testDefinitionInfoGetsTransferredToNode()
     {
-        $builder = new TreeBuilder();
+        $builder = new TreeBuilder('test');
 
-        $builder->root('test')->info('root info')
+        $builder->getRootNode()->info('root info')
             ->children()
                 ->node('child', 'variable')->info('child info')->defaultValue('default')
             ->end()
@@ -116,9 +112,9 @@ public function testDefinitionInfoGetsTransferredToNode()
 
     public function testDefinitionExampleGetsTransferredToNode()
     {
-        $builder = new TreeBuilder();
+        $builder = new TreeBuilder('test');
 
-        $builder->root('test')
+        $builder->getRootNode()
             ->example(array('key' => 'value'))
             ->children()
                 ->node('child', 'variable')->info('child info')->defaultValue('default')->example('example')
@@ -134,9 +130,9 @@ public function testDefinitionExampleGetsTransferredToNode()
 
     public function testDefaultPathSeparatorIsDot()
     {
-        $builder = new TreeBuilder();
+        $builder = new TreeBuilder('propagation');
 
-        $builder->root('propagation')
+        $builder->getRootNode()
             ->children()
                 ->node('foo', 'variable')->end()
                 ->arrayNode('child')
@@ -164,9 +160,9 @@ public function testDefaultPathSeparatorIsDot()
 
     public function testPathSeparatorIsPropagatedToChildren()
     {
-        $builder = new TreeBuilder();
+        $builder = new TreeBuilder('propagation');
 
-        $builder->root('propagation')
+        $builder->getRootNode()
             ->children()
                 ->node('foo', 'variable')->end()
                 ->arrayNode('child')
@@ -192,4 +188,13 @@ public function testPathSeparatorIsPropagatedToChildren()
         $this->assertInstanceOf('Symfony\Component\Config\Definition\BaseNode', $childChildren['foo']);
         $this->assertSame('propagation/child/foo', $childChildren['foo']->getPath());
     }
+
+    /**
+     * @group legacy
+     * @expectedDeprecation A tree builder without a root node is deprecated since Symfony 4.2 and will not be supported anymore in 5.0.
+     */
+    public function testInitializingTreeBuildersWithoutRootNode()
+    {
+        new TreeBuilder();
+    }
 }

src/Symfony/Component/Config/Tests/Definition/FinalizationTest.php

@@ -20,9 +20,9 @@ class FinalizationTest extends TestCase
 {
     public function testUnsetKeyWithDeepHierarchy()
     {
-        $tb = new TreeBuilder();
+        $tb = new TreeBuilder('config', 'array');
         $tree = $tb
-            ->root('config', 'array')
+            ->getRootNode()
                 ->children()
                     ->node('level1', 'array')
                         ->canBeUnset()