diff --git a/ortools/bop/bop_base.h b/ortools/bop/bop_base.h
index 0d349971d1..c8cdeaeb1f 100644
--- a/ortools/bop/bop_base.h
+++ b/ortools/bop/bop_base.h
@@ -130,7 +130,7 @@ class ProblemState {
   void set_assignment_preference(const std::vector<bool>& a) {
     assignment_preference_ = a;
   }
-  const std::vector<bool> assignment_preference() const {
+  std::vector<bool> assignment_preference() const {
     return assignment_preference_;
   }
 
diff --git a/ortools/bop/bop_fs.cc b/ortools/bop/bop_fs.cc
index df8115720b..a5ac22cd52 100644
--- a/ortools/bop/bop_fs.cc
+++ b/ortools/bop/bop_fs.cc
@@ -88,7 +88,7 @@ GuidedSatFirstSolutionGenerator::GuidedSatFirstSolutionGenerator(
       state_update_stamp_(ProblemState::kInitialStampValue),
       sat_solver_() {}
 
-GuidedSatFirstSolutionGenerator::~GuidedSatFirstSolutionGenerator() {}
+GuidedSatFirstSolutionGenerator::~GuidedSatFirstSolutionGenerator() = default;
 
 BopOptimizerBase::Status GuidedSatFirstSolutionGenerator::SynchronizeIfNeeded(
     const ProblemState& problem_state) {
@@ -221,7 +221,7 @@ BopRandomFirstSolutionGenerator::BopRandomFirstSolutionGenerator(
       random_(random),
       sat_propagator_(sat_propagator) {}
 
-BopRandomFirstSolutionGenerator::~BopRandomFirstSolutionGenerator() {}
+BopRandomFirstSolutionGenerator::~BopRandomFirstSolutionGenerator() = default;
 
 // Only run the RandomFirstSolution when there is an objective to minimize.
 bool BopRandomFirstSolutionGenerator::ShouldBeRun(
@@ -359,7 +359,7 @@ LinearRelaxation::LinearRelaxation(const BopParameters& parameters,
       problem_already_solved_(false),
       scaled_solution_cost_(glop::kInfinity) {}
 
-LinearRelaxation::~LinearRelaxation() {}
+LinearRelaxation::~LinearRelaxation() = default;
 
 BopOptimizerBase::Status LinearRelaxation::SynchronizeIfNeeded(
     const ProblemState& problem_state) {
diff --git a/ortools/bop/bop_lns.cc b/ortools/bop/bop_lns.cc
index 233deeee74..ef82aa855d 100644
--- a/ortools/bop/bop_lns.cc
+++ b/ortools/bop/bop_lns.cc
@@ -61,7 +61,7 @@ BopCompleteLNSOptimizer::BopCompleteLNSOptimizer(
       state_update_stamp_(ProblemState::kInitialStampValue),
       objective_terms_(objective_terms) {}
 
-BopCompleteLNSOptimizer::~BopCompleteLNSOptimizer() {}
+BopCompleteLNSOptimizer::~BopCompleteLNSOptimizer() = default;
 
 BopOptimizerBase::Status BopCompleteLNSOptimizer::SynchronizeIfNeeded(
     const ProblemState& problem_state, int num_relaxed_vars) {
@@ -223,7 +223,7 @@ BopAdaptiveLNSOptimizer::BopAdaptiveLNSOptimizer(
   CHECK(sat_propagator != nullptr);
 }
 
-BopAdaptiveLNSOptimizer::~BopAdaptiveLNSOptimizer() {}
+BopAdaptiveLNSOptimizer::~BopAdaptiveLNSOptimizer() = default;
 
 bool BopAdaptiveLNSOptimizer::ShouldBeRun(
     const ProblemState& problem_state) const {
diff --git a/ortools/bop/bop_lns.h b/ortools/bop/bop_lns.h
index ffdfb8dda1..5166a474b2 100644
--- a/ortools/bop/bop_lns.h
+++ b/ortools/bop/bop_lns.h
@@ -70,8 +70,8 @@ class BopCompleteLNSOptimizer : public BopOptimizerBase {
 // function here and a way to select between which one to call.
 class NeighborhoodGenerator {
  public:
-  NeighborhoodGenerator() {}
-  virtual ~NeighborhoodGenerator() {}
+  NeighborhoodGenerator() = default;
+  virtual ~NeighborhoodGenerator() = default;
 
   // Interface for the neighborhood generation.
   //
@@ -131,7 +131,7 @@ class ObjectiveBasedNeighborhood : public NeighborhoodGenerator {
   ObjectiveBasedNeighborhood(const BopConstraintTerms* objective_terms,
                              absl::BitGenRef random)
       : objective_terms_(*objective_terms), random_(random) {}
-  ~ObjectiveBasedNeighborhood() final {}
+  ~ObjectiveBasedNeighborhood() final = default;
 
  private:
   void GenerateNeighborhood(const ProblemState& problem_state,
@@ -149,7 +149,7 @@ class ConstraintBasedNeighborhood : public NeighborhoodGenerator {
   ConstraintBasedNeighborhood(const BopConstraintTerms* objective_terms,
                               absl::BitGenRef random)
       : objective_terms_(*objective_terms), random_(random) {}
-  ~ConstraintBasedNeighborhood() final {}
+  ~ConstraintBasedNeighborhood() final = default;
 
  private:
   void GenerateNeighborhood(const ProblemState& problem_state,
@@ -166,7 +166,7 @@ class RelationGraphBasedNeighborhood : public NeighborhoodGenerator {
  public:
   RelationGraphBasedNeighborhood(const sat::LinearBooleanProblem& problem,
                                  absl::BitGenRef random);
-  ~RelationGraphBasedNeighborhood() final {}
+  ~RelationGraphBasedNeighborhood() final = default;
 
  private:
   void GenerateNeighborhood(const ProblemState& problem_state,
diff --git a/ortools/bop/bop_ls.cc b/ortools/bop/bop_ls.cc
index 5663ce533f..e839e33dd7 100644
--- a/ortools/bop/bop_ls.cc
+++ b/ortools/bop/bop_ls.cc
@@ -51,7 +51,7 @@ LocalSearchOptimizer::LocalSearchOptimizer(absl::string_view name,
       assignment_iterator_(),
       random_(random) {}
 
-LocalSearchOptimizer::~LocalSearchOptimizer() {}
+LocalSearchOptimizer::~LocalSearchOptimizer() = default;
 
 bool LocalSearchOptimizer::ShouldBeRun(
     const ProblemState& problem_state) const {
diff --git a/ortools/bop/bop_ls.h b/ortools/bop/bop_ls.h
index d2f1f6ceb7..4d48dd8930 100644
--- a/ortools/bop/bop_ls.h
+++ b/ortools/bop/bop_ls.h
@@ -164,7 +164,7 @@ class LocalSearchOptimizer : public BopOptimizerBase {
 template <typename IntType>
 class BacktrackableIntegerSet {
  public:
-  BacktrackableIntegerSet() {}
+  BacktrackableIntegerSet() = default;
 
   // Prepares the class for integers in [0, n) and initializes the set to the
   // empty one. Note that this run in O(n). Once resized, it is better to call
diff --git a/ortools/bop/complete_optimizer.cc b/ortools/bop/complete_optimizer.cc
index ac742ae5d4..46c1eb6978 100644
--- a/ortools/bop/complete_optimizer.cc
+++ b/ortools/bop/complete_optimizer.cc
@@ -35,7 +35,7 @@ SatCoreBasedOptimizer::SatCoreBasedOptimizer(absl::string_view name)
   upper_bound_ = sat::kCoefficientMax;
 }
 
-SatCoreBasedOptimizer::~SatCoreBasedOptimizer() {}
+SatCoreBasedOptimizer::~SatCoreBasedOptimizer() = default;
 
 BopOptimizerBase::Status SatCoreBasedOptimizer::SynchronizeIfNeeded(
     const ProblemState& problem_state) {
diff --git a/ortools/bop/integral_solver.h b/ortools/bop/integral_solver.h
index e3ba2857e2..e7d455149b 100644
--- a/ortools/bop/integral_solver.h
+++ b/ortools/bop/integral_solver.h
@@ -28,7 +28,7 @@ namespace bop {
 class IntegralSolver {
  public:
   IntegralSolver();
-  ~IntegralSolver() {}
+  ~IntegralSolver() = default;
 
   // Sets the solver parameters.
   // See the proto for an extensive documentation.