1 files changed, 7 insertions, 4 deletions
diff --git a/extern/ceres/include/ceres/numeric_diff_cost_function.h b/extern/ceres/include/ceres/numeric_diff_cost_function.h
index cf7971cde79..6ec53175030 100644
--- a/extern/ceres/include/ceres/numeric_diff_cost_function.h
+++ b/extern/ceres/include/ceres/numeric_diff_cost_function.h
@@ -179,9 +179,10 @@ template <typename CostFunctor,
           NumericDiffMethodType method = CENTRAL,
           int kNumResiduals = 0,  // Number of residuals, or ceres::DYNAMIC
           int... Ns>              // Parameters dimensions for each block.
-class NumericDiffCostFunction : public SizedCostFunction<kNumResiduals, Ns...> {
+class NumericDiffCostFunction final
+    : public SizedCostFunction<kNumResiduals, Ns...> {
  public:
-  NumericDiffCostFunction(
+  explicit NumericDiffCostFunction(
       CostFunctor* functor,
       Ownership ownership = TAKE_OWNERSHIP,
       int num_residuals = kNumResiduals,
@@ -192,7 +193,7 @@ class NumericDiffCostFunction : public SizedCostFunction<kNumResiduals, Ns...> {
     }
   }
 
-  explicit NumericDiffCostFunction(NumericDiffCostFunction&& other)
+  NumericDiffCostFunction(NumericDiffCostFunction&& other)
       : functor_(std::move(other.functor_)), ownership_(other.ownership_) {}
 
   virtual ~NumericDiffCostFunction() {
@@ -219,7 +220,7 @@ class NumericDiffCostFunction : public SizedCostFunction<kNumResiduals, Ns...> {
       return false;
     }
 
-    if (jacobians == NULL) {
+    if (jacobians == nullptr) {
       return true;
     }
 
@@ -246,6 +247,8 @@ class NumericDiffCostFunction : public SizedCostFunction<kNumResiduals, Ns...> {
     return true;
   }
 
+  const CostFunctor& functor() const { return *functor_; }
+
  private:
   std::unique_ptr<CostFunctor> functor_;
   Ownership ownership_;