[rustdoc] Fix list margins

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

@@ -961,10 +961,13 @@ pre, .rustdoc.src .example-wrap, .example-wrap .src-line-numbers {
 }
 
 .docblock li {
-	margin-bottom: .8em;
+	margin-bottom: .4em;
 }
-.docblock li p {
-	margin-bottom: .1em;
+.docblock li p:not(:last-child) {
+	/* This margin is voluntarily smaller than `.docblock li` to keep the visual
+	   list element items separated while also having a visual separation (although
+	   smaller) for paragraphs. */
+	margin-bottom: .3em;
 }
 
 /* "where ..." clauses with block display are also smaller */

tests/rustdoc-gui/list-margins.goml

@@ -0,0 +1,11 @@
+// This test ensures that the documentation list markers are correctly placed.
+// It also serves as a regression test for <https://github.com/rust-lang/rust/issues/130622>.
+
+go-to: "file://" + |DOC_PATH| + "/test_docs/long_list/index.html"
+show-text: true
+
+// 0.3em
+assert-css: (".docblock li p:not(last-child)", {"margin-bottom": "4.8px"})
+assert-css: (".docblock li p + p:last-child", {"margin-bottom": "0px"})
+// 0.4em
+assert-css: (".docblock li", {"margin-bottom": "6.4px"})

tests/rustdoc-gui/src/test_docs/lib.rs

@@ -628,3 +628,27 @@ pub mod short_docs {
     /// subt_vec_num(x: &[f64], y: f64)
     pub fn subt_vec_num() {}
 }
+
+pub mod long_list {
+    //! bla
+    //!
+    //! * Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque et libero ut leo
+    //!   interdum laoreet vitae a mi. Aliquam erat volutpat. Suspendisse volutpat non quam non
+    //!   commodo.
+    //!
+    //!   Praesent enim neque, imperdiet sed nisl at, lobortis egestas augue. Sed vitae tristique
+    //!   augue. Phasellus vel pretium lectus.
+    //! * Praesent enim neque, imperdiet sed nisl at, lobortis egestas augue. Sed vitae tristique
+    //!   augue. Phasellus vel pretium lectus.
+    //! * Praesent enim neque, imperdiet sed nisl at, lobortis egestas augue. Sed vitae tristique
+    //!   augue. Phasellus vel pretium lectus.
+    //!
+    //! Another list:
+    //!
+    //! * [`TryFromBytes`](#a) indicates that a type may safely be converted from certain byte
+    //!   sequence (conditional on runtime checks)
+    //! * [`FromZeros`](#a) indicates that a sequence of zero bytes represents a valid instance of
+    //!   a type
+    //! * [`FromBytes`](#a) indicates that a type may safely be converted from an arbitrary byte
+    //!   sequence
+}