Rollup merge of #90089 - jsha:enum-fields-headings, r=camelid,GuillaumeGomez

Improve display of enum variants

Use h3 and h4 for the variant name and the "Fields" subheading.
Remove the "of T" part of the "Fields" subheading.
Remove border-bottom from "Fields" subheading.
Move docblock below "Fields" listing.

Fixes #90061

Demo:

https://jacob.hoffman-andrews.com/rust/xmlparser-updated/xmlparser/enum.Token.html#variants
https://jacob.hoffman-andrews.com/rust/fix-enum-variants/std/io/enum.ErrorKind.html#variants
https://jacob.hoffman-andrews.com/rust/fix-enum-variants/std/result/enum.Result.html#variants

r? ``@camelid``

src/test/rustdoc-gui/headings.goml

@@ -1,4 +1,4 @@
-// This test check that headers (a) have the correct heading level, (b) are the right size,
+// This test checks that headers (a) have the correct heading level, (b) are the right size,
 // and (c) have the correct underlining (or absence of underlining).
 // The sizes may change as design changes, but try to make sure a lower header is never bigger than
 // its parent headers. Also make sure lower headers don't have underlines when their parents lack
@@ -67,25 +67,25 @@ assert-css: ("h4#top-doc-prose-sub-sub-heading", {"border-bottom-width": "1px"})
 assert-css: ("h2#variants", {"font-size": "22.4px"})
 assert-css: ("h2#variants", {"border-bottom-width": "1px"})
 
-assert-css: ("h3#none-prose-title", {"font-size": "20.8px"})
-assert-css: ("h3#none-prose-title", {"border-bottom-width": "0px"})
-assert-css: ("h4#none-prose-sub-heading", {"font-size": "16px"})
-assert-css: ("h4#none-prose-sub-heading", {"border-bottom-width": "0px"})
+assert-css: ("h4#none-prose-title", {"font-size": "16px"})
+assert-css: ("h4#none-prose-title", {"border-bottom-width": "0px"})
+assert-css: ("h5#none-prose-sub-heading", {"font-size": "16px"})
+assert-css: ("h5#none-prose-sub-heading", {"border-bottom-width": "0px"})
 
-assert-css: ("h3#wrapped-prose-title", {"font-size": "20.8px"})
-assert-css: ("h3#wrapped-prose-title", {"border-bottom-width": "0px"})
-assert-css: ("h4#wrapped-prose-sub-heading", {"font-size": "16px"})
-assert-css: ("h4#wrapped-prose-sub-heading", {"border-bottom-width": "0px"})
+assert-css: ("h4#wrapped-prose-title", {"font-size": "16px"})
+assert-css: ("h4#wrapped-prose-title", {"border-bottom-width": "0px"})
+assert-css: ("h5#wrapped-prose-sub-heading", {"font-size": "16px"})
+assert-css: ("h5#wrapped-prose-sub-heading", {"border-bottom-width": "0px"})
 
-assert-css: ("h4#wrapped0-prose-title", {"font-size": "16px"})
-assert-css: ("h4#wrapped0-prose-title", {"border-bottom-width": "0px"})
-assert-css: ("h5#wrapped0-prose-sub-heading", {"font-size": "16px"})
-assert-css: ("h5#wrapped0-prose-sub-heading", {"border-bottom-width": "0px"})
+assert-css: ("h5#wrapped0-prose-title", {"font-size": "16px"})
+assert-css: ("h5#wrapped0-prose-title", {"border-bottom-width": "0px"})
+assert-css: ("h6#wrapped0-prose-sub-heading", {"font-size": "15.2px"})
+assert-css: ("h6#wrapped0-prose-sub-heading", {"border-bottom-width": "0px"})
 
-assert-css: ("h4#structy-prose-title", {"font-size": "16px"})
-assert-css: ("h4#structy-prose-title", {"border-bottom-width": "0px"})
-assert-css: ("h5#structy-prose-sub-heading", {"font-size": "16px"})
-assert-css: ("h5#structy-prose-sub-heading", {"border-bottom-width": "0px"})
+assert-css: ("h5#structy-prose-title", {"font-size": "16px"})
+assert-css: ("h5#structy-prose-title", {"border-bottom-width": "0px"})
+assert-css: ("h6#structy-prose-sub-heading", {"font-size": "15.2px"})
+assert-css: ("h6#structy-prose-sub-heading", {"border-bottom-width": "0px"})
 
 assert-css: ("h2#implementations", {"font-size": "22.4px"})
 assert-css: ("h2#implementations", {"border-bottom-width": "1px"})

src/test/rustdoc/enum-headings.rs

@@ -0,0 +1,40 @@
+#![crate_name = "foo"]
+// @has foo/enum.Token.html
+/// A token!
+/// # First
+/// Some following text...
+// @has - '//h2[@id="first"]' "First"
+pub enum Token {
+    /// A declaration!
+    /// # Variant-First
+    /// Some following text...
+    // @has - '//h4[@id="variant-first"]' "Variant-First"
+    Declaration {
+        /// A version!
+        /// # Variant-Field-First
+        /// Some following text...
+        // @has - '//h5[@id="variant-field-first"]' "Variant-Field-First"
+        version: String,
+    },
+    /// A Zoople!
+    /// # Variant-First
+    Zoople(
+        // @has - '//h5[@id="variant-tuple-field-first"]' "Variant-Tuple-Field-First"
+        /// Zoople's first variant!
+        /// # Variant-Tuple-Field-First
+        /// Some following text...
+        usize,
+    ),
+    /// Unfinished business!
+    /// # Non-Exhaustive-First
+    /// Some following text...
+    // @has - '//h4[@id="non-exhaustive-first"]' "Non-Exhaustive-First"
+    #[non_exhaustive]
+    Unfinished {
+        /// This is x.
+        /// # X-First
+        /// Some following text...
+        // @has - '//h5[@id="x-first"]' "X-First"
+        x: usize,
+    },
+}

src/test/rustdoc/tuple-struct-fields-doc.rs

@@ -20,10 +20,10 @@ pub struct Foo(
 
 // @has foo/enum.Bar.html
 // @has - '//pre[@class="rust enum"]' 'BarVariant(String),'
-// @matches - '//*[@id="variant.BarVariant.fields"]/h3' '^Tuple Fields of BarVariant$'
+// @matches - '//*[@id="variant.BarVariant.fields"]/h4' '^Tuple Fields$'
 // @has - '//*[@id="variant.BarVariant.field.0"]' '0: String'
 // @has - '//*[@id="variant.BarVariant.fields"]//*[@class="docblock"]' 'Hello docs'
-// @matches - '//*[@id="variant.FooVariant.fields"]/h3' '^Fields of FooVariant$'
+// @matches - '//*[@id="variant.FooVariant.fields"]/h4' '^Fields$'
 pub enum Bar {
     BarVariant(
         /// Hello docs