Extract closure for trait ref filtering.

clippy_lints/src/trait_bounds.rs

@@ -334,13 +334,16 @@ fn into_comparable_trait_ref(trait_ref: &TraitRef<'_>) -> ComparableTraitRef {
 fn rollup_traits(cx: &LateContext<'_>, bounds: &[GenericBound<'_>], msg: &str) {
     let mut map = FxHashMap::default();
     let mut repeated_res = false;
-    for bound in bounds.iter().filter_map(|bound| {
+
+    let only_comparable_trait_refs = |bound: &GenericBound<'_>| {
         if let GenericBound::Trait(t, _) = bound {
             Some((into_comparable_trait_ref(&t.trait_ref), t.span))
         } else {
             None
         }
-    }) {
+    };
+
+    for bound in bounds.iter().filter_map(only_comparable_trait_refs) {
         let (comparable_bound, span_direct) = bound;
         if map.insert(comparable_bound, span_direct).is_some() {
             repeated_res = true;