Rollup merge of #141377 - nnethercote:rm-unnecessary-is_empty-checks, r=GuillaumeGomez

Remove unnecessary `is_empty` checks

Part of #137978.

r? `@GuillaumeGomez`

Author: matthiaskrgr

compiler/rustc_span/src/symbol.rs

@@ -2823,7 +2823,7 @@ impl Ident {
     /// Whether this would be the identifier for a tuple field like `self.0`, as
     /// opposed to a named field like `self.thing`.
     pub fn is_numeric(self) -> bool {
-        !self.name.is_empty() && self.as_str().bytes().all(|b| b.is_ascii_digit())
+        self.as_str().bytes().all(|b| b.is_ascii_digit())
     }
 }
 

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -59,12 +59,7 @@ fn filter_assoc_items_by_name_and_namespace(
     ident: Ident,
     ns: Namespace,
 ) -> impl Iterator<Item = &ty::AssocItem> {
-    let iter: Box<dyn Iterator<Item = &ty::AssocItem>> = if !ident.name.is_empty() {
-        Box::new(tcx.associated_items(assoc_items_of).filter_by_name_unhygienic(ident.name))
-    } else {
-        Box::new([].iter())
-    };
-    iter.filter(move |item| {
+    tcx.associated_items(assoc_items_of).filter_by_name_unhygienic(ident.name).filter(move |item| {
         item.namespace() == ns && tcx.hygienic_eq(ident, item.ident(tcx), assoc_items_of)
     })
 }