Merge branch '4.0'

* 4.0:
  Have weak_vendors ignore deprecations from outside
  [HttpFoundation] fixed return type of method HeaderBag::get
  [HttpFoundation] Added "resource" type on Request::create docblock
  [Console] Fix using finally where the catch can also fail
  [Process] Skip environment variables with false value in Process
  Revert "bug #25789  Enableable ArrayNodeDefinition is disabled for empty configuration (kejwmen)"
  Formatting fix in upgrade 3.0 document
  don't split lines on carriage returns when dumping
  trim spaces from unquoted scalar values
  Revert "bug #25851 [Validator] Conflict with egulias/email-validator 2.0 (emodric)"
  [DI] compilation perf tweak
  [Validator] Conflict with egulias/email-validator 2.0
  [Validator] add missing parent isset and add test

Author: nicolas-grekas

Constraint.php

@@ -214,6 +214,16 @@ public function __get($option)
         throw new InvalidOptionsException(sprintf('The option "%s" does not exist in constraint %s', $option, get_class($this)), array($option));
     }
 
+    /**
+     * @param string $option The option name
+     *
+     * @return bool
+     */
+    public function __isset($option)
+    {
+        return 'groups' === $option;
+    }
+
     /**
      * Adds the given group if this constraint is in the Default group.
      *

Tests/Constraints/FileTest.php

@@ -26,6 +26,16 @@ public function testMaxSize($maxSize, $bytes, $binaryFormat)
 
         $this->assertSame($bytes, $file->maxSize);
         $this->assertSame($binaryFormat, $file->binaryFormat);
+        $this->assertTrue($file->__isset('maxSize'));
+    }
+
+    public function testMagicIsset()
+    {
+        $file = new File(array('maxSize' => 1));
+
+        $this->assertTrue($file->__isset('maxSize'));
+        $this->assertTrue($file->__isset('groups'));
+        $this->assertFalse($file->__isset('toto'));
     }
 
     /**