Replace $form_state['input'] with FormState::getUserInput()

Well I love this patch. I am ++ on using $input = &$form_state->getUserInput(); to set or get the values from the FormStateInterface::$input. And it'll discourage user to use it. I haven't found any objectionable thing while reviewing it. So nothing to fix here.

1. +++ b/core/lib/Drupal/Core/Form/FormBuilder.php
   @@ -176,9 +176,10 @@ public function buildForm($form_id, FormStateInterface &$form_state) {
   +    $input = &$form_state->getUserInput();
   +    if (!isset($input)) {
   

   Nice!!!

2. +++ b/core/modules/system/src/Tests/Batch/ProcessingTest.php
   @@ -105,7 +105,7 @@ function testBatchFormMultipleBatches() {
   -    // hanlders and logging of corresponding $form_state[{values'].
   
   @@ -123,7 +123,7 @@ function testBatchFormProgrammatic() {
   -    // hanlders and logging of corresponding $form_state[{values'].
   

   lol hanlders and $form_state[{values']

3. +++ b/core/modules/views_ui/admin.inc
   @@ -328,7 +328,9 @@ function views_ui_standard_display_dropdown(&$form, FormStateInterface $form_sta
   -  $path = "admin/structure/views/$ajax/$form_state[form_key]/$name/$form_state[display_id]";
   +  $form_key = $form_state->get('form_key');
   +  $display_id = $form_state->get('display_id');
   +  $path = "admin/structure/views/$ajax/$form_key/$name/$display_id";
   

   I am going to let this slide :D

Green. I'll add it to main change notice.

Here is the update https://www.drupal.org/node/2310411/revisions/view/7513005/7516151

+++ b/core/lib/Drupal/Core/Installer/Form/SiteSettingsForm.php
@@ -43,22 +43,23 @@ public function buildForm(array $form, FormStateInterface $form_state) {
+    $input = &$form_state->getUserInput();
+    if (!isset($input['driver']) && $database = Database::getConnectionInfo()) {
+      $input['driver'] = $database['default']['driver'];

Using a method called getUserInput to set user input feels icky. Especially since we have a few $form_state->set('input,.. around.

Not sure if we should be doing it this way.

+++ b/core/lib/Drupal/Core/Form/FormStateInterface.php
@@ -176,6 +176,28 @@ public function has($property);
+   * These are raw and unvalidated, so should not be used without a thorough
+   * understanding of security implications. In almost all cases, code should
+   * use self::getValues() and self::getValue() exclusively.

Should these docs be added to setUserInput as well? Or something similar.

What about getRawInput()? I think such name better explains what the method returns.

Input is always raw so naming it getRawInput doesn't make sense.
@tim.plunkett thanks for the explanation.
As #5 is addressed so RTBC. Added suggested commit message to issue summary.

Committed and pushed to 8.x. Thanks!