Don't hide fields of enum struct variants

* The toggle adds visual clutter
* It's easy to miss that there are fields
* Tuple variant fields are always shown, so it is inconsistent to hide
  struct variant fields
* It's annoying to have to click the toggle every time

Author: camelid

src/librustdoc/html/render/print_item.rs

@@ -1029,14 +1029,12 @@ fn item_enum(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, e: &clean::Enum
 
             use crate::clean::Variant;
             if let clean::VariantItem(Variant::Struct(ref s)) = *variant.kind {
-                let count_fields = s.fields.len();
-                toggle_open(w, format_args!("{} field{}", count_fields, pluralize(count_fields)));
                 let variant_id = cx.derive_id(format!(
                     "{}.{}.fields",
                     ItemType::Variant,
                     variant.name.as_ref().unwrap()
                 ));
-                write!(w, "<div class=\"autohide sub-variant\" id=\"{id}\">", id = variant_id);
+                write!(w, "<div class=\"sub-variant\" id=\"{id}\">", id = variant_id);
                 write!(
                     w,
                     "<h3>Fields of <b>{name}</b></h3><div>",
@@ -1064,7 +1062,6 @@ fn item_enum(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, e: &clean::Enum
                     }
                 }
                 w.write_str("</div></div>");
-                toggle_close(w);
             }
         }
     }

src/librustdoc/html/static/css/rustdoc.css

@@ -1072,7 +1072,7 @@ a.test-arrow:hover{
 	padding-top: 1px;
 }
 
-#main > details > .sub-variant > h3 {
+#main .sub-variant > h3 {
 	font-size: 15px;
 	margin-left: 25px;
 	margin-bottom: 5px;

src/test/rustdoc/toggle-item-contents.rs

@@ -62,8 +62,7 @@ pub struct PrivStruct {
 }
 
 // @has 'toggle_item_contents/enum.Enum.html'
-// @count - '//details[@class="rustdoc-toggle type-contents-toggle"]' 1
-// @has - '//details[@class="rustdoc-toggle type-contents-toggle"]' 'Show 2 fields'
+// @!has - '//details[@class="rustdoc-toggle type-contents-toggle"]'
 pub enum Enum {
     A, B, C,
     D {
@@ -73,8 +72,7 @@ pub enum Enum {
 }
 
 // @has 'toggle_item_contents/enum.EnumStructVariant.html'
-// @count - '//details[@class="rustdoc-toggle type-contents-toggle"]' 1
-// @has - '//details[@class="rustdoc-toggle type-contents-toggle"]' 'Show 1 field'
+// @!has - '//details[@class="rustdoc-toggle type-contents-toggle"]'
 pub enum EnumStructVariant {
     A, B, C,
     D {