fix some clippy::complexity

compiler/rustc_borrowck/src/lib.rs

@@ -528,7 +528,7 @@ impl<'cx, 'tcx> BorrowckInferCtxt<'cx, 'tcx> {
     where
         F: Fn() -> RegionCtxt,
     {
-        let next_region = self.infcx.next_nll_region_var(origin.clone());
+        let next_region = self.infcx.next_nll_region_var(origin);
         let vid = next_region.as_var();
 
         if cfg!(debug_assertions) && !self.inside_canonicalization_ctxt() {

compiler/rustc_hir_analysis/src/collect/predicates_of.rs

@@ -645,9 +645,8 @@ pub(super) fn implied_predicates_with_filter(
     };
 
     // Combine the two lists to form the complete set of superbounds:
-    let implied_bounds = &*tcx
-        .arena
-        .alloc_from_iter(superbounds.predicates().into_iter().chain(where_bounds_that_match));
+    let implied_bounds =
+        &*tcx.arena.alloc_from_iter(superbounds.predicates().chain(where_bounds_that_match));
     debug!(?implied_bounds);
 
     // Now require that immediate supertraits are converted,

compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs

@@ -164,24 +164,20 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 {
                     for param in
                         [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
+                            .into_iter()
+                            .flatten()
                     {
-                        if let Some(param) = param {
-                            let refined_expr = self.point_at_field_if_possible(
-                                def_id,
-                                param,
-                                variant_def_id,
-                                fields,
-                            );
-
-                            match refined_expr {
-                                None => {}
-                                Some((refined_expr, _)) => {
-                                    error.obligation.cause.span = refined_expr
-                                        .span
-                                        .find_ancestor_in_same_ctxt(error.obligation.cause.span)
-                                        .unwrap_or(refined_expr.span);
-                                    return true;
-                                }
+                        let refined_expr =
+                            self.point_at_field_if_possible(def_id, param, variant_def_id, fields);
+
+                        match refined_expr {
+                            None => {}
+                            Some((refined_expr, _)) => {
+                                error.obligation.cause.span = refined_expr
+                                    .span
+                                    .find_ancestor_in_same_ctxt(error.obligation.cause.span)
+                                    .unwrap_or(refined_expr.span);
+                                return true;
                             }
                         }
                     }

compiler/rustc_monomorphize/src/partitioning/default.rs

@@ -89,7 +89,7 @@ impl<'tcx> Partitioner<'tcx> for DefaultPartitioning {
         }
 
         PreInliningPartitioning {
-            codegen_units: codegen_units.into_values().map(|codegen_unit| codegen_unit).collect(),
+            codegen_units: codegen_units.into_values().collect(),
             roots,
             internalization_candidates,
         }

compiler/rustc_query_impl/src/profiling_support.rs

@@ -231,7 +231,7 @@ pub(crate) fn alloc_self_profile_query_strings_for_query_cache<'tcx, C>(
             // locked while doing so. Instead we copy out the
             // `(query_key, dep_node_index)` pairs and release the lock again.
             let mut query_keys_and_indices = Vec::new();
-            query_cache.iter(&mut |k, _, i| query_keys_and_indices.push((k.clone(), i)));
+            query_cache.iter(&mut |k, _, i| query_keys_and_indices.push((*k, i)));
 
             // Now actually allocate the strings. If allocating the strings
             // generates new entries in the query cache, we'll miss them but

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -1349,7 +1349,7 @@ impl LinkCollector<'_, '_> {
                         if has_derive_trait_collision {
                             candidates.macro_ns = None;
                         }
-                        candidates.into_iter().filter_map(|res| res).flatten().collect::<Vec<_>>()
+                        candidates.into_iter().flatten().flatten().collect::<Vec<_>>()
                     }
                 }
             }