Rollup merge of rust-lang#140248 - GuillaumeGomez:fix-impl-block-items-indent, r=notriddle

Fix impl block items indent

Fixes rust-lang#139771.

Now, all impl block "before impl block items" indent are the same (ie, item info and documentation).

With this fix, it looks like this:

![Screenshot From 2025-04-24 12-32-40](https://github.com/user-attachments/assets/907803a2-2949-4d01-afa5-fc3132d10ff2)

You can test it [here](https://rustdoc.crud.net/imperio/fix-impl-block-items-indent/foo/struct.Context.html).

r? `@notriddle`

Author: matthiaskrgr

src/librustdoc/html/render/mod.rs

@@ -2086,6 +2086,7 @@ fn render_impl(
                     .split_summary_and_content()
                 })
                 .unwrap_or((None, None));
+
             write!(
                 w,
                 "{}",
@@ -2097,24 +2098,19 @@ fn render_impl(
                     use_absolute,
                     aliases,
                     before_dox.as_deref(),
+                    trait_.is_none() && impl_.items.is_empty(),
                 )
             )?;
             if toggled {
                 w.write_str("</summary>")?;
             }
 
-            if before_dox.is_some() {
-                if trait_.is_none() && impl_.items.is_empty() {
-                    w.write_str(
-                        "<div class=\"item-info\">\
-                         <div class=\"stab empty-impl\">This impl block contains no items.</div>\
-                     </div>",
-                    )?;
-                }
-                if let Some(after_dox) = after_dox {
-                    write!(w, "<div class=\"docblock\">{after_dox}</div>")?;
-                }
+            if before_dox.is_some()
+                && let Some(after_dox) = after_dox
+            {
+                write!(w, "<div class=\"docblock\">{after_dox}</div>")?;
             }
+
             if !default_impl_items.is_empty() || !impl_items.is_empty() {
                 w.write_str("<div class=\"impl-items\">")?;
                 close_tags.push("</div>");
@@ -2182,6 +2178,7 @@ fn render_impl_summary(
     // in documentation pages for trait with automatic implementations like "Send" and "Sync".
     aliases: &[String],
     doc: Option<&str>,
+    impl_is_empty: bool,
 ) -> impl fmt::Display {
     fmt::from_fn(move |w| {
         let inner_impl = i.inner_impl();
@@ -2237,6 +2234,13 @@ fn render_impl_summary(
         }
 
         if let Some(doc) = doc {
+            if impl_is_empty {
+                w.write_str(
+                    "<div class=\"item-info\">\
+                         <div class=\"stab empty-impl\">This impl block contains no items.</div>\
+                     </div>",
+                )?;
+            }
             write!(w, "<div class=\"docblock\">{doc}</div>")?;
         }
 

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

@@ -2319,7 +2319,10 @@ details.toggle > summary:not(.hideme)::before {
 	doc block while aligning it with the impl block items. */
 .implementors-toggle > .docblock,
 /* We indent trait items as well. */
-#main-content > .methods > :not(.item-info) {
+#main-content > .methods > :not(.item-info),
+.impl > .item-info,
+.impl > .docblock,
+.impl + .docblock {
 	margin-left: var(--impl-items-indent);
 }
 

tests/rustdoc-gui/docblock-table-overflow.goml

@@ -11,7 +11,7 @@ assert-property: (".top-doc .docblock table", {"scrollWidth": "1572"})
 // Checking it works on other doc blocks as well...
 
 // Logically, the ".docblock" and the "<p>" should have the same scroll width (if we exclude the margin).
-assert-property: ("#implementations-list > details .docblock", {"scrollWidth": 816})
+assert-property: ("#implementations-list > details .docblock", {"scrollWidth": 835})
 assert-property: ("#implementations-list > details .docblock > p", {"scrollWidth": 835})
 // However, since there is overflow in the <table>, its scroll width is bigger.
 assert-property: ("#implementations-list > details .docblock table", {"scrollWidth": "1572"})

tests/rustdoc-gui/impl-doc-indent.goml

@@ -0,0 +1,16 @@
+// Checks the impl block docs have the correct indent.
+go-to: "file://" + |DOC_PATH| + "/test_docs/impls_indent/struct.Context.html"
+
+// First we ensure that the impl items are indent (more on the right of the screen) than the
+// impl itself.
+store-position: ("#impl-Context", {"x": impl_x})
+store-position: ("#impl-Context > .item-info", {"x": impl_item_x})
+assert: |impl_x| < |impl_item_x|
+
+// And we ensure that all impl items have the same indent.
+assert-position: ("#impl-Context > .docblock", {"x": |impl_item_x|})
+assert-position: ("#impl-Context + .docblock", {"x": |impl_item_x|})
+
+// Same with the collapsible impl block.
+assert-position: ("#impl-Context-1 > .docblock", {"x": |impl_item_x|})
+assert-position: (".implementors-toggle > summary + .docblock", {"x": |impl_item_x|})

tests/rustdoc-gui/item-info-overflow.goml

@@ -21,7 +21,7 @@ compare-elements-property: (
 )
 assert-property: (
     "#impl-SimpleTrait-for-LongItemInfo2 .item-info",
-    {"scrollWidth": "916"},
+    {"scrollWidth": "935"},
 )
 // Just to be sure we're comparing the correct "item-info":
 assert-text: (

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

@@ -740,3 +740,29 @@ pub mod SidebarSort {
     impl Sort for Cell<u8> {}
     impl<'a> Sort for &'a str {}
 }
+
+pub mod impls_indent {
+    pub struct Context;
+
+    /// Working with objects.
+    ///
+    /// # Safety
+    ///
+    /// Functions that take indices of locals do not check bounds on these indices;
+    /// the caller must ensure that the indices are less than the number of locals
+    /// in the current stack frame.
+    impl Context {
+    }
+
+    /// Working with objects.
+    ///
+    /// # Safety
+    ///
+    /// Functions that take indices of locals do not check bounds on these indices;
+    /// the caller must ensure that the indices are less than the number of locals
+    /// in the current stack frame.
+    impl Context {
+        /// bla
+        pub fn bar() {}
+    }
+}