Rollup merge of rust-lang#90018 - GuillaumeGomez:too-long-item-names, r=jsha

Fix rustdoc UI for very long type names

Fixes rust-lang#89972.

While working on it, I also discovered that when the item name is too long, it also breaks the flow of the page.

To make things right, I also renamed the `type-decl` CSS class into `item-decl` (because this PR also generates it for more than type declarations).

So here are the before/after screenshots:

![Screenshot from 2021-10-18 16-58-03](https://user-images.githubusercontent.com/3050060/137757247-637fcf04-4406-49c6-8a8a-18c2074aacd9.png)
![Screenshot from 2021-10-18 16-58-26](https://user-images.githubusercontent.com/3050060/137757252-17935e63-53b3-449f-a535-7be91ff0e257.png)

![Screenshot from 2021-10-18 16-58-07](https://user-images.githubusercontent.com/3050060/137757278-8b12e348-2980-4fc4-8853-bef99d58981f.png)
![Screenshot from 2021-10-18 16-58-28](https://user-images.githubusercontent.com/3050060/137757282-534a0e1b-3016-49ba-b3ac-e45bdb9035cb.png)

r? `@jsha`

Author: GuillaumeGomez

src/librustdoc/html/render/print_item.rs

@@ -482,24 +482,26 @@ fn item_function(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, f: &clean::
         + name.as_str().len()
         + generics_len;
 
-    wrap_item(w, "fn", |w| {
-        render_attributes_in_pre(w, it, "");
-        w.reserve(header_len);
-        write!(
-            w,
-            "{vis}{constness}{asyncness}{unsafety}{abi}fn \
-             {name}{generics}{decl}{notable_traits}{where_clause}",
-            vis = vis,
-            constness = constness,
-            asyncness = asyncness,
-            unsafety = unsafety,
-            abi = abi,
-            name = name,
-            generics = f.generics.print(cx),
-            where_clause = print_where_clause(&f.generics, cx, 0, true),
-            decl = f.decl.full_print(header_len, 0, f.header.asyncness, cx),
-            notable_traits = notable_traits_decl(&f.decl, cx),
-        );
+    wrap_into_docblock(w, |w| {
+        wrap_item(w, "fn", |w| {
+            render_attributes_in_pre(w, it, "");
+            w.reserve(header_len);
+            write!(
+                w,
+                "{vis}{constness}{asyncness}{unsafety}{abi}fn \
+                 {name}{generics}{decl}{notable_traits}{where_clause}",
+                vis = vis,
+                constness = constness,
+                asyncness = asyncness,
+                unsafety = unsafety,
+                abi = abi,
+                name = name,
+                generics = f.generics.print(cx),
+                where_clause = print_where_clause(&f.generics, cx, 0, true),
+                decl = f.decl.full_print(header_len, 0, f.header.asyncness, cx),
+                notable_traits = notable_traits_decl(&f.decl, cx),
+            );
+        });
     });
     document(w, cx, it, None, HeadingOffset::H2)
 }
@@ -844,16 +846,18 @@ fn item_trait(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, t: &clean::Tra
 }
 
 fn item_trait_alias(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, t: &clean::TraitAlias) {
-    wrap_item(w, "trait-alias", |w| {
-        render_attributes_in_pre(w, it, "");
-        write!(
-            w,
-            "trait {}{}{} = {};",
-            it.name.as_ref().unwrap(),
-            t.generics.print(cx),
-            print_where_clause(&t.generics, cx, 0, true),
-            bounds(&t.bounds, true, cx)
-        );
+    wrap_into_docblock(w, |w| {
+        wrap_item(w, "trait-alias", |w| {
+            render_attributes_in_pre(w, it, "");
+            write!(
+                w,
+                "trait {}{}{} = {};",
+                it.name.as_ref().unwrap(),
+                t.generics.print(cx),
+                print_where_clause(&t.generics, cx, 0, true),
+                bounds(&t.bounds, true, cx)
+            );
+        });
     });
 
     document(w, cx, it, None, HeadingOffset::H2);
@@ -866,16 +870,18 @@ fn item_trait_alias(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, t: &clea
 }
 
 fn item_opaque_ty(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, t: &clean::OpaqueTy) {
-    wrap_item(w, "opaque", |w| {
-        render_attributes_in_pre(w, it, "");
-        write!(
-            w,
-            "type {}{}{where_clause} = impl {bounds};",
-            it.name.as_ref().unwrap(),
-            t.generics.print(cx),
-            where_clause = print_where_clause(&t.generics, cx, 0, true),
-            bounds = bounds(&t.bounds, false, cx),
-        );
+    wrap_into_docblock(w, |w| {
+        wrap_item(w, "opaque", |w| {
+            render_attributes_in_pre(w, it, "");
+            write!(
+                w,
+                "type {}{}{where_clause} = impl {bounds};",
+                it.name.as_ref().unwrap(),
+                t.generics.print(cx),
+                where_clause = print_where_clause(&t.generics, cx, 0, true),
+                bounds = bounds(&t.bounds, false, cx),
+            );
+        });
     });
 
     document(w, cx, it, None, HeadingOffset::H2);
@@ -894,20 +900,37 @@ fn item_typedef(
     t: &clean::Typedef,
     is_associated: bool,
 ) {
-    wrap_item(w, "typedef", |w| {
-        render_attributes_in_pre(w, it, "");
-        if !is_associated {
-            write!(w, "{}", it.visibility.print_with_space(it.def_id, cx));
-        }
-        write!(
-            w,
-            "type {}{}{where_clause} = {type_};",
-            it.name.as_ref().unwrap(),
-            t.generics.print(cx),
-            where_clause = print_where_clause(&t.generics, cx, 0, true),
-            type_ = t.type_.print(cx),
-        );
-    });
+    fn write_content(
+        w: &mut Buffer,
+        cx: &Context<'_>,
+        it: &clean::Item,
+        t: &clean::Typedef,
+        is_associated: bool,
+    ) {
+        wrap_item(w, "typedef", |w| {
+            render_attributes_in_pre(w, it, "");
+            if !is_associated {
+                write!(w, "{}", it.visibility.print_with_space(it.def_id, cx));
+            }
+            write!(
+                w,
+                "type {}{}{where_clause} = {type_};",
+                it.name.as_ref().unwrap(),
+                t.generics.print(cx),
+                where_clause = print_where_clause(&t.generics, cx, 0, true),
+                type_ = t.type_.print(cx),
+            );
+        });
+    }
+
+    // If this is an associated typedef, we don't want to wrap it into a docblock.
+    if is_associated {
+        write_content(w, cx, it, t, is_associated);
+    } else {
+        wrap_into_docblock(w, |w| {
+            write_content(w, cx, it, t, is_associated);
+        });
+    }
 
     document(w, cx, it, None, HeadingOffset::H2);
 
@@ -1142,32 +1165,34 @@ fn item_macro(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, t: &clean::Mac
 }
 
 fn item_proc_macro(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, m: &clean::ProcMacro) {
-    let name = it.name.as_ref().expect("proc-macros always have names");
-    match m.kind {
-        MacroKind::Bang => {
-            wrap_item(w, "macro", |w| {
-                write!(w, "{}!() {{ /* proc-macro */ }}", name);
-            });
-        }
-        MacroKind::Attr => {
-            wrap_item(w, "attr", |w| {
-                write!(w, "#[{}]", name);
-            });
-        }
-        MacroKind::Derive => {
-            wrap_item(w, "derive", |w| {
-                write!(w, "#[derive({})]", name);
-                if !m.helpers.is_empty() {
-                    w.push_str("\n{\n");
-                    w.push_str("    // Attributes available to this derive:\n");
-                    for attr in &m.helpers {
-                        writeln!(w, "    #[{}]", attr);
+    wrap_into_docblock(w, |w| {
+        let name = it.name.as_ref().expect("proc-macros always have names");
+        match m.kind {
+            MacroKind::Bang => {
+                wrap_item(w, "macro", |w| {
+                    write!(w, "{}!() {{ /* proc-macro */ }}", name);
+                });
+            }
+            MacroKind::Attr => {
+                wrap_item(w, "attr", |w| {
+                    write!(w, "#[{}]", name);
+                });
+            }
+            MacroKind::Derive => {
+                wrap_item(w, "derive", |w| {
+                    write!(w, "#[derive({})]", name);
+                    if !m.helpers.is_empty() {
+                        w.push_str("\n{\n");
+                        w.push_str("    // Attributes available to this derive:\n");
+                        for attr in &m.helpers {
+                            writeln!(w, "    #[{}]", attr);
+                        }
+                        w.push_str("}\n");
                     }
-                    w.push_str("}\n");
-                }
-            });
+                });
+            }
         }
-    }
+    });
     document(w, cx, it, None, HeadingOffset::H2)
 }
 
@@ -1177,38 +1202,40 @@ fn item_primitive(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item) {
 }
 
 fn item_constant(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, c: &clean::Constant) {
-    wrap_item(w, "const", |w| {
-        render_attributes_in_code(w, it);
+    wrap_into_docblock(w, |w| {
+        wrap_item(w, "const", |w| {
+            render_attributes_in_code(w, it);
 
-        write!(
-            w,
-            "{vis}const {name}: {typ}",
-            vis = it.visibility.print_with_space(it.def_id, cx),
-            name = it.name.as_ref().unwrap(),
-            typ = c.type_.print(cx),
-        );
+            write!(
+                w,
+                "{vis}const {name}: {typ}",
+                vis = it.visibility.print_with_space(it.def_id, cx),
+                name = it.name.as_ref().unwrap(),
+                typ = c.type_.print(cx),
+            );
 
-        let value = c.value(cx.tcx());
-        let is_literal = c.is_literal(cx.tcx());
-        let expr = c.expr(cx.tcx());
-        if value.is_some() || is_literal {
-            write!(w, " = {expr};", expr = Escape(&expr));
-        } else {
-            w.write_str(";");
-        }
+            let value = c.value(cx.tcx());
+            let is_literal = c.is_literal(cx.tcx());
+            let expr = c.expr(cx.tcx());
+            if value.is_some() || is_literal {
+                write!(w, " = {expr};", expr = Escape(&expr));
+            } else {
+                w.write_str(";");
+            }
 
-        if !is_literal {
-            if let Some(value) = &value {
-                let value_lowercase = value.to_lowercase();
-                let expr_lowercase = expr.to_lowercase();
+            if !is_literal {
+                if let Some(value) = &value {
+                    let value_lowercase = value.to_lowercase();
+                    let expr_lowercase = expr.to_lowercase();
 
-                if value_lowercase != expr_lowercase
-                    && value_lowercase.trim_end_matches("i32") != expr_lowercase
-                {
-                    write!(w, " // {value}", value = Escape(value));
+                    if value_lowercase != expr_lowercase
+                        && value_lowercase.trim_end_matches("i32") != expr_lowercase
+                    {
+                        write!(w, " // {value}", value = Escape(value));
+                    }
                 }
             }
-        }
+        });
     });
 
     document(w, cx, it, None, HeadingOffset::H2)
@@ -1268,30 +1295,34 @@ fn item_struct(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, s: &clean::St
 }
 
 fn item_static(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, s: &clean::Static) {
-    wrap_item(w, "static", |w| {
-        render_attributes_in_code(w, it);
-        write!(
-            w,
-            "{vis}static {mutability}{name}: {typ}",
-            vis = it.visibility.print_with_space(it.def_id, cx),
-            mutability = s.mutability.print_with_space(),
-            name = it.name.as_ref().unwrap(),
-            typ = s.type_.print(cx)
-        );
+    wrap_into_docblock(w, |w| {
+        wrap_item(w, "static", |w| {
+            render_attributes_in_code(w, it);
+            write!(
+                w,
+                "{vis}static {mutability}{name}: {typ}",
+                vis = it.visibility.print_with_space(it.def_id, cx),
+                mutability = s.mutability.print_with_space(),
+                name = it.name.as_ref().unwrap(),
+                typ = s.type_.print(cx)
+            );
+        });
     });
     document(w, cx, it, None, HeadingOffset::H2)
 }
 
 fn item_foreign_type(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item) {
-    wrap_item(w, "foreigntype", |w| {
-        w.write_str("extern {\n");
-        render_attributes_in_code(w, it);
-        write!(
-            w,
-            "    {}type {};\n}}",
-            it.visibility.print_with_space(it.def_id, cx),
-            it.name.as_ref().unwrap(),
-        );
+    wrap_into_docblock(w, |w| {
+        wrap_item(w, "foreigntype", |w| {
+            w.write_str("extern {\n");
+            render_attributes_in_code(w, it);
+            write!(
+                w,
+                "    {}type {};\n}}",
+                it.visibility.print_with_space(it.def_id, cx),
+                it.name.as_ref().unwrap(),
+            );
+        });
     });
 
     document(w, cx, it, None, HeadingOffset::H2);
@@ -1374,7 +1405,7 @@ fn wrap_into_docblock<F>(w: &mut Buffer, f: F)
 where
     F: FnOnce(&mut Buffer),
 {
-    w.write_str("<div class=\"docblock type-decl\">");
+    w.write_str("<div class=\"docblock item-decl\">");
     f(w);
     w.write_str("</div>")
 }

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

@@ -254,7 +254,10 @@ code, pre, a.test-arrow, .code-header {
 pre {
 	padding: 14px;
 }
-.type-decl pre {
+.docblock.item-decl {
+	margin-left: 0;
+}
+.item-decl pre {
 	overflow-x: auto;
 }
 
@@ -550,6 +553,7 @@ nav.sub {
 	flex-grow: 1;
 	margin: 0px;
 	padding: 0px;
+	overflow-wrap: anywhere;
 }
 
 .in-band > code, .in-band > .code-header {

src/librustdoc/html/static/css/themes/ayu.css

@@ -220,7 +220,7 @@ body.source .example-wrap pre.rust a {
 	background: #333;
 }
 
-.docblock:not(.type-decl) a:not(.srclink):not(.test-arrow),
+.docblock:not(.item-decl) a:not(.srclink):not(.test-arrow),
 .docblock-short a:not(.srclink):not(.test-arrow), .item-info a,
 #help a {
 	color: #39AFD7;

src/librustdoc/html/static/css/themes/dark.css

@@ -181,7 +181,7 @@ body.source .example-wrap pre.rust a {
 	background: #333;
 }
 
-.docblock:not(.type-decl) a:not(.srclink):not(.test-arrow),
+.docblock:not(.item-decl) a:not(.srclink):not(.test-arrow),
 .docblock-short a:not(.srclink):not(.test-arrow), .item-info a,
 #help a {
 	color: #D2991D;

src/librustdoc/html/static/css/themes/light.css

@@ -176,7 +176,7 @@ body.source .example-wrap pre.rust a {
 	background: #eee;
 }
 
-.docblock:not(.type-decl) a:not(.srclink):not(.test-arrow),
+.docblock:not(.item-decl) a:not(.srclink):not(.test-arrow),
 .docblock-short a:not(.srclink):not(.test-arrow), .item-info a,
 #help a {
 	color: #3873AD;

src/test/rustdoc-gui/basic.goml

@@ -1,4 +1,4 @@
 goto: file://|DOC_PATH|/test_docs/index.html
 assert: ("#functions")
 goto: ./struct.Foo.html
-assert: ("div.type-decl")
+assert: ("div.item-decl")