Rollup merge of #118600 - GuillaumeGomez:fields-heading, r=notriddle

[rustdoc] Don't generate the "Fields" heading if there is no field displayed

Fixes #118195.

If no field is displayed, we should not generate the `Fields` heading in enum struct variants.

r? ``@notriddle``

Author: GuillaumeGomez

Diff for: src/librustdoc/html/render/print_item.rs

@@ -1737,7 +1737,14 @@ fn item_variants(
         w.write_str("</h3></section>");
 
         let heading_and_fields = match &variant_data.kind {
-            clean::VariantKind::Struct(s) => Some(("Fields", &s.fields)),
+            clean::VariantKind::Struct(s) => {
+                // If there is no field to display, no need to add the heading.
+                if s.fields.iter().any(|f| !f.is_doc_hidden()) {
+                    Some(("Fields", &s.fields))
+                } else {
+                    None
+                }
+            }
             clean::VariantKind::Tuple(fields) => {
                 // Documentation on tuple variant fields is rare, so to reduce noise we only emit
                 // the section if at least one field is documented.

Diff for: tests/rustdoc/enum-variant-fields-heading.rs

@@ -0,0 +1,18 @@
+// This is a regression test for <https://github.com/rust-lang/rust/issues/118195>.
+// It ensures that the "Fields" heading is not generated if no field is displayed.
+
+#![crate_name = "foo"]
+
+// @has 'foo/enum.Foo.html'
+// @has - '//*[@id="variant.A"]' 'A'
+// @count - '//*[@id="variant.A.fields"]' 0
+// @has - '//*[@id="variant.B"]' 'B'
+// @count - '//*[@id="variant.B.fields"]' 0
+// @snapshot variants - '//*[@id="main-content"]/*[@class="variants"]'
+
+pub enum Foo {
+    /// A variant with no fields
+    A {},
+    /// A variant with hidden fields
+    B { #[doc(hidden)] a: u8 },
+}

Diff for: tests/rustdoc/enum-variant-fields-heading.variants.html

@@ -0,0 +1,3 @@
+<div class="variants"><section id="variant.A" class="variant"><a href="#variant.A" class="anchor">&#167;</a><h3 class="code-header">A</h3></section><div class="docblock"><p>A variant with no fields</p>
+</div><section id="variant.B" class="variant"><a href="#variant.B" class="anchor">&#167;</a><h3 class="code-header">B</h3></section><div class="docblock"><p>A variant with hidden fields</p>
+</div></div>