non-class type return values are non-modifiable, const qualifier is ignored (-Wignored-qualifiers)

ex:
int func() { return 0; }
main() { func() = 5; } // invalid

src/mlpack/methods/neighbor_search/neighbor_search.hpp

@@ -59,7 +59,7 @@ class QueryStat
       : bound(SortPolicy::WorstDistance()) { }
 
   //! Get the bound.
-  const double Bound() const { return bound; }
+  double Bound() const { return bound; }
   //! Modify the bound.
   double& Bound() { return bound; }
 };

src/mlpack/methods/neighbor_search/sort_policies/furthest_neighbor_sort.hpp

@@ -77,7 +77,7 @@ class FurthestNeighborSort
    *
    * @return 0
    */
-  static inline const double WorstDistance() { return 0; }
+  static inline double WorstDistance() { return 0; }
 
   /**
    * Return what should represent the best possible distance with this
@@ -86,7 +86,7 @@ class FurthestNeighborSort
    *
    * @return DBL_MAX
    */
-  static inline const double BestDistance() { return DBL_MAX; }
+  static inline double BestDistance() { return DBL_MAX; }
 };
 
 }; // namespace neighbor

src/mlpack/methods/neighbor_search/sort_policies/nearest_neighbor_sort.hpp

@@ -81,7 +81,7 @@ class NearestNeighborSort
    *
    * @return DBL_MAX
    */
-  static inline const double WorstDistance() { return DBL_MAX; }
+  static inline double WorstDistance() { return DBL_MAX; }
 
   /**
    * Return what should represent the best possible distance with this
@@ -90,7 +90,7 @@ class NearestNeighborSort
    *
    * @return 0.0
    */
-  static inline const double BestDistance() { return 0.0; }
+  static inline double BestDistance() { return 0.0; }
 };
 
 }; // namespace neighbor

src/mlpack/tests/save_restore_utility_test.cpp

@@ -45,7 +45,7 @@ class SaveRestoreTest
     return success;
   }
 
-  const size_t AnInt() { return anInt; }
+  size_t AnInt() { return anInt; }
   void AnInt(size_t s) { this->anInt = s; }
 };