Replace !placeholder with @placeholder in a few remaining places

:)

RTBC as these should all be safe to convert:

1. +++ b/core/includes/install.inc
   @@ -558,7 +558,7 @@ function drupal_verify_profile($install_state) {
   +      'description' => t('The following modules are required but were not found. Move them into the appropriate modules subdirectory, such as <em>/modules</em>. Missing modules: @modules', array('@modules' => implode(', ', $modules))),
   

   machine name

2. +++ b/core/modules/datetime/src/Plugin/Field/FieldWidget/DateTimeDatelistWidget.php
   @@ -141,10 +141,10 @@ function settingsForm(array $form, FormStateInterface $form_state) {
   +    $summary[] = t('Date part order: @order', array('@order' => $this->getSetting('date_order')));
   

   three letters in a row only (YMD / DMY / MDY)

3. +++ b/core/modules/datetime/src/Plugin/Field/FieldWidget/DateTimeDatelistWidget.php
   @@ -141,10 +141,10 @@ function settingsForm(array $form, FormStateInterface $form_state) {
   +      $summary[] = t('Time type: @time_type', array('@time_type' => $this->getSetting('time_type')));
   +      $summary[] = t('Time increments: @increment', array('@increment' => $this->getSetting('increment')));
   

   integers only

4. +++ b/core/modules/language/src/Plugin/Derivative/LanguageBlock.php
   @@ -26,7 +26,7 @@ public function getDerivativeDefinitions($base_plugin_definition) {
   +        $this->derivatives[$type]['admin_label'] = t('Language switcher (@type)', array('@type' => $info[$type]['name']));
   

   Always wrapped in t()

5. +++ b/core/modules/migrate/src/MigrateExecutable.php
   @@ -148,8 +148,8 @@ public function __construct(MigrationInterface $migration, MigrateMessageInterfa
   +              array('@limit' => $limit)));
   

   integer

Actually 1 is returns a string of markup that is not marked safe (not machine names).

So maybe we need to wait for that suffix helper that's still to do?

/edit: seems @dawehner already spotted this :)

We could, but we don't explicitly support render arrays in hook_requirements yet, so #2505499: Explicitly support render arrays in hook_requirements() would probably need to go in first in order to do #6? A renderPlain might also work but are we sure that will work in the installer?

Discussed this with @pwolanin and just a SafeString::create() might be the safest bet for now, as well as maybe a Xss::filterAdmin() in case $modules ever becomes unsafe when code changes.

@dawehner - since drupal_render() it not available there, the alternative we discussed of making a render array and rendering it is not possible.

I don't think this is wrong during install/requirements.

I don't even this this needs the Xss::filter(). If we are concerned it shoudl just use Html::escape()

ok, let's try this?

@pwolanin that sure looks a bit cleaner than the SafeString::create(), assuming the renderer works during the installer. Will do manual testing and post screenshots.

+++ b/core/includes/install.inc
@@ -12,6 +12,8 @@
+use Drupal\Core\Render\SafeString;
+use Drupal\Component\Utility\Xss;

Not used anymore

fixing trailing commas and use statements

+++ b/core/includes/install.inc
@@ -549,16 +549,21 @@ function drupal_verify_profile($install_state) {
+  $count = count($missing_modules);
+  if ($count) {
+    $build = array();
+
     foreach ($missing_modules as $module) {
-      $modules[] = '<span class="admin-missing">' . Unicode::ucfirst($module) . '</span>';
+      $count--;
+      $build[] = array('#markup' => '<span class="admin-missing">' . Unicode::ucfirst($module) . '</span>', '#suffix' => $count ? ', ' : '');
     }

Let's use the inline item list for this... see #2505931: Remove SafeMarkup::set in ViewListBuilder

Needs the if (count($missing_modules)) {

@dawehner that sounds like a bug - we saw this before when removing the file scan fallback

This looks OK. Screenshots for reference:

#20 is unrelated to this patch - and for the drush output the PlainTextFormattedOutput thing might be a great use case later on as this will format the HTML nicely for CLI output as well.

Oops @dawehner I didn't mean to post that, we cross posted. Let me do an interdiff and see if they are the same.

Let me look at the "before" output of the Required modules error as well to see if this needs a CSS followup - I kind of like the fact they are now red and on a separate line, but would be good to at least know if this is changing the look of the output in any way.

Re-uploading @dawehner's patch as that is where the screenshots come from (and #22 was escaping)

The only difference with the current behavior is that the list of items is wrapping to the next line as it's a div, but this is a general problem - we run into this elsewhere as well, so it would be good if we could fix this everywhere.

This should either be a span or be an inline div, but fixing this may not be in scope here. Leaving RTBC for a core committer to have a look at this.

The new line in the comma list will be addressed by #2557367: Fix inline list CSS.

Committed fc45b90 and pushed to 8.0.x. Thanks!

I cancelled the pifr test of #27 hence the failure. I'm trusting the DrupalCI test result.