Rollup merge of #122530 - klensy:as_str, r=fee1-dead

less symbol interner locks

This reduces instructions under 1% (in rustdoc run), but essentially free.

compiler/rustc_resolve/src/rustdoc.rs

@@ -167,12 +167,13 @@ pub fn unindent_doc_fragments(docs: &mut [DocFragment]) {
 ///
 /// Note: remove the trailing newline where appropriate
 pub fn add_doc_fragment(out: &mut String, frag: &DocFragment) {
-    let s = frag.doc.as_str();
-    let mut iter = s.lines();
-    if s.is_empty() {
+    if frag.doc == kw::Empty {
         out.push('\n');
         return;
     }
+    let s = frag.doc.as_str();
+    let mut iter = s.lines();
+
     while let Some(line) = iter.next() {
         if line.chars().any(|c| !c.is_whitespace()) {
             assert!(line.len() >= frag.indent);

src/librustdoc/html/render/mod.rs

@@ -1698,9 +1698,10 @@ fn render_impl(
                     let id = cx.derive_id(format!("{item_type}.{name}"));
                     let source_id = trait_
                         .and_then(|trait_| {
-                            trait_.items.iter().find(|item| {
-                                item.name.map(|n| n.as_str().eq(name.as_str())).unwrap_or(false)
-                            })
+                            trait_
+                                .items
+                                .iter()
+                                .find(|item| item.name.map(|n| n == *name).unwrap_or(false))
                         })
                         .map(|item| format!("{}.{name}", item.type_()));
                     write!(w, "<section id=\"{id}\" class=\"{item_type}{in_trait_class}\">");