Merge branch '4.0'

* 4.0:
  [HttpKernel] Make ServiceValueResolver work if controller namespace starts with a backslash in routing
  Add d-block to bootstrap 4 alerts
  [Console] Don't go past exact matches when autocompleting
  [DI] Improve error message for non-autowirable scalar argument
  Disable autoloader call on interface_exists check
  [Validator] Fix LazyLoadingMetadataFactory with PSR6Cache for non classname if tested values isn't an existing class
  [HttpKernel] Dont create mock cookie for new sessions in tests

Author: nicolas-grekas

Resources/views/Form/bootstrap_4_layout.html.twig

@@ -283,7 +283,7 @@
 
 {% block form_errors -%}
     {%- if errors|length > 0 -%}
-        <span class="{% if form is not rootform %}invalid-feedback d-block{% else %}alert alert-danger{% endif %}">
+        <span class="{% if form is not rootform %}invalid-feedback{% else %}alert alert-danger{% endif %} d-block">
             {%- for error in errors -%}
                 <span class="mb-0 d-block">
                     <span class="initialism form-error-icon badge badge-danger">{{ 'Error'|trans({}, 'validators') }}</span> <span class="form-error-message">{{ error.message }}</span>