avoid collecting into vecs in some places

compiler/rustc_hir_analysis/src/astconv/mod.rs

@@ -860,10 +860,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                              traits with associated type `{name}`, you could use the \
                              fully-qualified path",
                         ),
-                        traits
-                            .iter()
-                            .map(|trait_str| format!("<Example as {trait_str}>::{name}"))
-                            .collect::<Vec<_>>(),
+                        traits.iter().map(|trait_str| format!("<Example as {trait_str}>::{name}")),
                         Applicability::HasPlaceholders,
                     );
                 }