integrating c++17 fixes from #959 (ref:https://github.com/flann-lib/flann/pull/392), fixed pop_t error (https://github.com/flann-lib/flann/commit/b6e37553de0dd47dc8fc9035ba5aef163981b6a4)

corelib/src/rtflann/util/heap.h

@@ -115,8 +115,11 @@ public:
         count = 0;
     }
 
-    struct CompareT : public std::binary_function<T,T,bool>
+    struct CompareT
     {
+        using result_type = bool;
+        using first_argument_type = T;
+        using second_argument_type = T;
         bool operator()(const T& t_1, const T& t_2) const
         {
             return t_2 < t_1;

corelib/src/rtflann/util/lsh_table.h

@@ -47,6 +47,7 @@
 #endif
 #include <math.h>
 #include <stddef.h>
+#include <random>
 
 #include "rtflann/util/dynamic_bitset.h"
 #include "rtflann/util/matrix.h"
@@ -364,7 +365,9 @@ inline LshTable<unsigned char>::LshTable(unsigned int feature_size, unsigned int
     // A bit brutal but fast to code
     std::vector<size_t> indices(feature_size * CHAR_BIT);
     for (size_t i = 0; i < feature_size * CHAR_BIT; ++i) indices[i] = i;
-    std::random_shuffle(indices.begin(), indices.end());
+    std::random_device rd;
+    std::mt19937 g(rd());
+    std::shuffle(indices.begin(), indices.end(), g);
 
     // Generate a random set of order of subsignature_size_ bits
     for (unsigned int i = 0; i < key_size_; ++i) {

corelib/src/rtflann/util/random.h

@@ -35,6 +35,7 @@
 #include <cstdlib>
 #include <cstddef>
 #include <vector>
+#include <random>
 
 #include "rtflann/general.h"
 
@@ -76,13 +77,6 @@ inline int rand_int(int high = RAND_MAX, int low = 0)
 }
 
 
-class RandomGenerator
-{
-public:
-    ptrdiff_t operator() (ptrdiff_t i) { return rand_int(i); }
-};
-
-
 /**
  * Random number generator that returns a distinct number from
  * the [0,n) interval each time.
@@ -110,14 +104,15 @@ public:
      */
     void init(int n)
     {
-        static RandomGenerator generator;
         // create and initialize an array of size n
         vals_.resize(n);
         size_ = n;
         for (int i = 0; i < size_; ++i) vals_[i] = i;
 
         // shuffle the elements in the array
-        std::random_shuffle(vals_.begin(), vals_.end(), generator);
+        std::random_device rd;
+        std::mt19937 g(rd());
+        std::shuffle(vals_.begin(), vals_.end(), g);
 
         counter_ = 0;
     }