Merge branch '3.4' into 4.4

* 3.4:
  Fixes sprintf(): Too few arguments in form transformer
  [Console] Fix QuestionHelper::disableStty()
  validate subforms in all validation groups
  Update Hungarian translations
  Add meaningful message when Process is not installed (ProcessHelper)
  [PropertyAccess] Fix TypeError parsing again.
  [Form] add missing Czech validators translation
  [Validator] add missing Czech translations
  never directly validate Existence (Required/Optional) constraints

Author: nicolas-grekas

Helper/ProcessHelper.php

@@ -38,6 +38,10 @@ class ProcessHelper extends Helper
      */
     public function run(OutputInterface $output, $cmd, $error = null, callable $callback = null, $verbosity = OutputInterface::VERBOSITY_VERY_VERBOSE)
     {
+        if (!class_exists(Process::class)) {
+            throw new \LogicException('The Process helper requires the "Process" component. Install "symfony/process" to use it.');
+        }
+
         if ($output instanceof ConsoleOutputInterface) {
             $output = $output->getErrorOutput();
         }

Helper/QuestionHelper.php

@@ -33,7 +33,7 @@ class QuestionHelper extends Helper
 {
     private $inputStream;
     private static $shell;
-    private static $stty;
+    private static $stty = true;
 
     /**
      * Asks a question to the user.
@@ -107,7 +107,7 @@ private function doAsk(OutputInterface $output, Question $question)
         $inputStream = $this->inputStream ?: STDIN;
         $autocomplete = $question->getAutocompleterCallback();
 
-        if (null === $autocomplete || !Terminal::hasSttyAvailable()) {
+        if (null === $autocomplete || !self::$stty || !Terminal::hasSttyAvailable()) {
             $ret = false;
             if ($question->isHidden()) {
                 try {
@@ -417,7 +417,7 @@ private function getHiddenResponse(OutputInterface $output, $inputStream, bool $
             return $value;
         }
 
-        if (Terminal::hasSttyAvailable()) {
+        if (self::$stty && Terminal::hasSttyAvailable()) {
             $sttyMode = shell_exec('stty -g');
 
             shell_exec('stty -echo');

Tests/Helper/QuestionHelperTest.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Component\Console\Tests\Helper;
 
+use Symfony\Component\Console\Exception\InvalidArgumentException;
 use Symfony\Component\Console\Formatter\OutputFormatter;
 use Symfony\Component\Console\Helper\FormatterHelper;
 use Symfony\Component\Console\Helper\HelperSet;
@@ -783,6 +784,35 @@ public function testTraversableAutocomplete()
         $this->assertEquals('FooBundle', $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question));
     }
 
+    public function testDisableSttby()
+    {
+        if (!Terminal::hasSttyAvailable()) {
+            $this->markTestSkipped('`stty` is required to test autocomplete functionality');
+        }
+
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('invalid');
+
+        QuestionHelper::disableStty();
+        $dialog = new QuestionHelper();
+        $dialog->setHelperSet(new HelperSet([new FormatterHelper()]));
+
+        $question = new ChoiceQuestion('Please select a bundle', [1 => 'AcmeDemoBundle', 4 => 'AsseticBundle']);
+        $question->setMaxAttempts(1);
+
+        // <UP ARROW><UP ARROW><NEWLINE><DOWN ARROW><DOWN ARROW><NEWLINE>
+        // Gives `AcmeDemoBundle` with stty
+        $inputStream = $this->getInputStream("\033[A\033[A\n\033[B\033[B\n");
+
+        try {
+            $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question);
+        } finally {
+            $reflection = new \ReflectionProperty(QuestionHelper::class, 'stty');
+            $reflection->setAccessible(true);
+            $reflection->setValue(null, true);
+        }
+    }
+
     public function testTraversableMultiselectAutocomplete()
     {
         // <NEWLINE>