Rollup merge of #91687 - euclio:tuple-variant-field-section, r=GuillaumeGomez

rustdoc: do not emit tuple variant fields if none are documented

Fixes #90824.

Before:

![2021-12-15T22:26:41](https://user-images.githubusercontent.com/1372438/146302871-4d265433-b9aa-4e53-adfb-e7cb92107180.png)

After:

![2021-12-15T22:27:01](https://user-images.githubusercontent.com/1372438/146302872-e39eda3d-2fb2-4fb9-aae7-2008e4e1b4dd.png)

1 files changed, 14 insertions, 0 deletions

diff --git a/src/test/rustdoc/tuple-struct-fields-doc.rs b/src/test/rustdoc/tuple-struct-fields-doc.rs
index 2e339fe8264..31426131bc2 100644
--- a/src/test/rustdoc/tuple-struct-fields-doc.rs
+++ b/src/test/rustdoc/tuple-struct-fields-doc.rs
@@ -24,6 +24,9 @@ pub struct Foo(
 // @has - '//*[@id="variant.BarVariant.field.0"]' '0: String'
 // @has - '//*[@id="variant.BarVariant.fields"]//*[@class="docblock"]' 'Hello docs'
 // @matches - '//*[@id="variant.FooVariant.fields"]/h4' '^Fields$'
+// @has - '//*[@id="variant.BazVariant.fields"]//*[@class="docblock"]' 'dox'
+// @has - '//*[@id="variant.OtherVariant.fields"]//*[@class="docblock"]' 'dox'
+// @!matches - '//*[@id="variant.QuuxVariant.fields"]/h4' '^Tuple Fields$'
 pub enum Bar {
     BarVariant(
         /// Hello docs
@@ -33,4 +36,15 @@ pub enum Bar {
        /// hello
        x: u32,
     },
+    BazVariant(
+        String,
+        /// dox
+        u32,
+    ),
+    OtherVariant(
+        /// dox
+        String,
+        u32,
+    ),
+    QuuxVariant(String),
 }