Issue #2023091 by djevans, badrange: Drupal does not allow W3C compliant...

Issue #2023091 by djevans, badrange: Drupal does not allow W3C compliant language codes where you target a numeric region

core/modules/language/src/Form/LanguageFormBase.php

@@ -100,8 +100,11 @@ public function commonForm(array &$form) {
    */
   public function validateCommon(array $form, FormStateInterface $form_state) {
     // Ensure sane field values for langcode and name.
-    if (!isset($form['langcode_view']) && preg_match('@[^a-zA-Z_-]@', $form_state->getValue('langcode'))) {
-      $form_state->setErrorByName('langcode', $this->t('%field may only contain characters a-z, underscores, or hyphens.', array('%field' => $form['langcode']['#title'])));
+    if (!isset($form['langcode_view']) && !preg_match('@^[a-zA-Z]{1,8}(-[a-zA-Z0-9]{1,8})*$@', $form_state->getValue('langcode'))) {
+      $form_state->setErrorByName('langcode', $this->t('%field must be a valid language tag as <a href="@url">defined by the W3C</a>.', array(
+        '%field' => $form['langcode']['#title'],
+        '@url' => 'http://www.w3.org/International/articles/language-tags/',
+      )));
     }
     if ($form_state->getValue('label') != String::checkPlain($form_state->getValue('label'))) {
       $form_state->setErrorByName('label', $this->t('%field cannot contain any markup.', array('%field' => $form['label']['#title'])));

core/modules/language/src/Tests/LanguageCustomLanguageConfigurationTest.php

@@ -54,10 +54,30 @@ public function testLanguageConfiguration() {
       'direction' => LanguageInterface::DIRECTION_LTR,
     );
     $this->drupalPostForm('admin/config/regional/language/add', $edit, t('Add custom language'));
-    $this->assertRaw(t('%field may only contain characters a-z, underscores, or hyphens.', array('%field' => t('Language code'))));
+
+    $this->assertRaw(t('%field must be a valid language tag as <a href="@url">defined by the W3C</a>.', array(
+      '%field' => t('Language code'),
+      '@url' => 'http://www.w3.org/International/articles/language-tags/',
+    )));
+
     $this->assertRaw(t('%field cannot contain any markup.', array('%field' => t('Language name in English'))));
     $this->assertUrl(\Drupal::url('language.add', array(), array('absolute' => TRUE)), [], 'Correct page redirection.');
 
+    // Test adding a custom language with a numeric region code.
+    $edit = array(
+      'predefined_langcode' => 'custom',
+      'langcode' => 'es-419',
+      'label' => 'Latin American Spanish',
+      'direction' => LanguageInterface::DIRECTION_LTR,
+    );
+
+    $this->drupalPostForm('admin/config/regional/language/add', $edit, t('Add custom language'));
+    $this->assertRaw(t(
+      'The language %language has been created and can now be used.',
+      array('%language' => $edit['label'])
+    ));
+    $this->assertUrl(\Drupal::url('language.admin_overview', array(), array('absolute' => TRUE)), [], 'Correct page redirection.');
+
     // Test validation of existing language values.
     $edit = array(
       'predefined_langcode' => 'custom',