Move type equality check to just before push

Author: smoelius

clippy_lints/src/dereference.rs

@@ -1127,20 +1127,17 @@ fn replace_types<'tcx>(
     deque.push_back((param_ty, new_ty));
 
     while let Some((param_ty, new_ty)) = deque.pop_front() {
-        let new_generic_arg = ty::GenericArg::from(new_ty);
-
         // If `replaced.is_empty()`, then `param_ty` and `new_ty` are those initially passed in.
-        if substs[param_ty.index as usize] != new_generic_arg
-            && !fn_sig
-                .inputs_and_output
-                .iter()
-                .enumerate()
-                .all(|(i, ty)| (replaced.is_empty() && i == arg_index) || !contains_ty(ty, param_ty.to_ty(cx.tcx)))
+        if !fn_sig
+            .inputs_and_output
+            .iter()
+            .enumerate()
+            .all(|(i, ty)| (replaced.is_empty() && i == arg_index) || !contains_ty(ty, param_ty.to_ty(cx.tcx)))
         {
             return false;
         }
 
-        substs[param_ty.index as usize] = new_generic_arg;
+        substs[param_ty.index as usize] = ty::GenericArg::from(new_ty);
 
         // The `replaced.insert(...)` check provides some protection against infinite loops.
         if replaced.insert(param_ty.index) {
@@ -1155,7 +1152,9 @@ fn replace_types<'tcx>(
                         .mk_projection(assoc_item.def_id, cx.tcx.mk_substs_trait(new_ty, &[]));
                     let projected_ty = cx.tcx.normalize_erasing_regions(cx.param_env, projection);
 
-                    deque.push_back((*term_param_ty, projected_ty));
+                    if substs[term_param_ty.index as usize] != ty::GenericArg::from(projected_ty) {
+                        deque.push_back((*term_param_ty, projected_ty));
+                    }
                 }
             }
         }