Merge branch '4.1'

* 4.1:
  fixed typo
  [FrameworkBundle] fixed brackets position in method calls
  Add placeholder support in bootstrap 4 file fields
  [Form] Improve rendering of `file` field in bootstrap 4
  [Form] Fix PHPDoc for FormConfigBuilder $dataClass argument
  [Security] Update user phpdoc on tokens
  [WebProfilerBundle] Fixed icon alignment issue using Bootstrap 4.1.2
  suppress side effects in 'get' or 'has' methods of NamespacedAttributeBag
  [HttpFoundation] reset callback on StreamedResponse when setNotModified() is called
  [HttpFoundation] Fixed phpdoc for get method of HeaderBag
  fix typo in ContainerBuilder docblock
  [Form/Profiler] Massively reducing memory footprint of form profiling pages by removing redundant 'form' variable from view variables.
  [Console] correctly return parameter's default value on "--"
  [DependencyInjection] add missing test for #27710
  [EventDispatcher] Clear orphaned events on TraceableEventDispatcher::reset
  Fix serialization of abstract items with groups across multiple entities

Author: fabpot

Resources/views/Form/bootstrap_4_layout.html.twig

@@ -114,6 +114,20 @@
     </div>
 {%- endblock percent_widget %}
 
+{% block file_widget -%}
+    <div class="form-group">
+        <{{ element|default('div') }} class="custom-file">
+            {%- set type = type|default('file') -%}
+            {{- block('form_widget_simple') -}}
+            <label for="{{ form.vars.id }}" class="custom-file-label">
+                {%- if attr.placeholder is defined -%}
+                    {{- translation_domain is same as(false) ? attr.placeholder : attr.placeholder|trans({}, translation_domain) -}}
+                {%- endif -%}
+            </label>
+        </{{ element|default('div') }}>
+    </div>
+{% endblock %}
+
 {% block form_widget_simple -%}
     {% if type is not defined or type != 'hidden' %}
         {%- set attr = attr|merge({class: (attr.class|default('') ~ (type|default('') == 'file' ? ' custom-file-input' : ' form-control'))|trim}) -%}
@@ -186,8 +200,6 @@
         {%- if compound is defined and compound -%}
             {%- set element = 'legend' -%}
             {%- set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ ' col-form-label')|trim}) -%}
-        {% elseif type is defined and type == 'file' %}
-            {%- set label_attr = label_attr|merge({for: id, class: (label_attr.class|default('') ~ ' custom-file-label')|trim}) -%}
         {%- else -%}
             {%- set label_attr = label_attr|merge({for: id}) -%}
         {%- endif -%}
@@ -269,15 +281,6 @@
     </{{ element|default('div') }}>
 {%- endblock form_row %}
 
-{% block file_row -%}
-    <div class="form-group">
-        <{{ element|default('div') }} class="custom-file">
-            {{- form_widget(form) -}}
-            {{- form_label(form) -}}
-        </{{ element|default('div') }}>
-    </div>
-{% endblock %}
-
 {# Errors #}
 
 {% block form_errors -%}