Auto merge of #87449 - matthiaskrgr:clippyy_v2, r=nagisa

more clippy::complexity fixes

(also a couple of clippy::perf fixes)

compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs

@@ -124,11 +124,10 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             self.impl_similar_to(trait_ref, obligation).unwrap_or_else(|| trait_ref.def_id());
         let trait_ref = trait_ref.skip_binder();
 
-        let mut flags = vec![];
-        flags.push((
+        let mut flags = vec![(
             sym::ItemContext,
             self.describe_enclosure(obligation.cause.body_id).map(|s| s.to_owned()),
-        ));
+        )];
 
         match obligation.cause.code {
             ObligationCauseCode::BuiltinDerivedObligation(..)

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -290,13 +290,9 @@ fn suggest_restriction(
     } else {
         // Trivial case: `T` needs an extra bound: `T: Bound`.
         let (sp, suggestion) = match (
-            generics
-                .params
-                .iter()
-                .filter(|p| {
-                    !matches!(p.kind, hir::GenericParamKind::Type { synthetic: Some(_), .. })
-                })
-                .next(),
+            generics.params.iter().find(|p| {
+                !matches!(p.kind, hir::GenericParamKind::Type { synthetic: Some(_), .. })
+            }),
             super_traits,
         ) {
             (_, None) => predicate_constraint(